Engine conversions were one of the first things I started researching before I even got my first Landy, is one of the most of debated forum questions, and my research has spawned a whole section on the site devoted to the topic! Basically, with series engines being so woefully under-powered and not particularly economical in compensation, putting something else in is one of the first things many new or potential owners ask about.
And, with SO many possibilities; not just by way of actual engine choice; but beyond, into the realms of swapping transmission bits, or even axles, there is no way to cover all the things that have, could or might be done by way of putting a different engine in a Land Rover engine bay. It is similarly impossible to try and say what 'conversions' might be 'best' or most suited to you or what you want the car to do; and not just by way of the car and the engine, but where you are in the world.
In the UK, engines we can commonly come by include things like Ford V6's, Jaguar straight 6's; Rover V8's and Perkins Diesels. In America, Ford or Chevrolet V8's are quite easy to come by; rover V8's and Jag 6's not so. In Australia, they have the Leyland 4.4L version of the Rover V8, and Holden straight sixes. And what you can actually lay your hands on can significantly influence what's 'Best'.
So, in this article; what I have done, is look at the standard Series Land rover engine; which will be the starting point for most; and consider its vices and virtues. Because on cold rational 'balance' what's 'best', MIGHT just be to leave the original engine in there.
Having considered that; before looking for alternatives and considering what benefits they might have over the Stock four-Pot; I have looked at Conversion Principles in general, and the sort of work that is typically involved. But, standard series gearbox, is a bit weak, so anything significantly more powerful might raise the question of changing the gearbox as well; so I have had a bit of a look at the Gearbox & Transmission, and looked at what could be done in this area and the significance of what else that might mean you have to mess with.
But, a conversion isn't just about the engineering, end of the day, you have to have the time, resources, and money to do they job, and be able to live with it afterwards; so I have had a look at the Viability, Practicality & 'Livibility' of a conversion , the sort of hassles likely to be encountered working on or putting up with a converted car in day to day use, before having a think about Standard and Condition, and the compromises between costs, performance and life/reliability, because it's all too easy to go to the effort and expense of a conversion, and put in something with a lot of 'cheap' performance, but the real cost is that that engine hasn't much useful life left in it!
Finally, I have cherry picked a selection of the more 'common' conversions that have been undertaken, mainly UK conversions; and of those have chosen to look at:
Land Rover 2.5 NAD or Td - from early Diesel 90/110 or Sherpa Van
The Rover V8 -from Range Rover / Discovery or Rover Saloon
The Rover 200/300Tdi - From Discovery / Defender
Perkins 'Prima', Montego Engine
Ford Granada 2.8/3.0 V6.
Ford/Peugot 2.3/2.5TD Transit engine
That's a round half dozen engines, about half Diesels, half Petrol's, half from the Rover catalogue, half from other manufacturers, and represent a fair cross section of the sort of conversions most people would undertake. And I have compared their various virtues and vices to assess what might be more or less suitable for any application; basically to provide a 'bench-mark' that you can compare similar alternatives to.
Idea of the article is not to try and make any choice for you, or even make any recommendations, but point you in the right direction to weigh up the alternatives and make the best choice for you.
That SAID! After an awful lot of going around the reakin on the topic and discussions on the forums, I am finding it ever so much harder to remain so impassive on the matter. The more and more I look at the subject, the more that my opinion is polarised between two SIGNIFICANTLY more useful solutions, than the rest. Which I've explained in a bit more detail in the Conclusion at the end, where I've also bunged some useful links to other related articles on the site and other useful or interesting stuff on the topic on the web.
So! to air my recommendations before looking at how I get to them; If you want something easy to live with, don't want to break the bank to get it, and can resolve yourself to live with the poor economy and performance of a Standard Series Four Pot; do so. Put your efforts and finances into fettling servicing or overhauling your standard engine, so you at least get the 'best' performance and economy you can from it, and leave the car standard.
If you really want to boost the performance, then really, the Rover V8, takes some beating; but if you are going to the expense and effort of doing a conversion; this one gives most reward for it. It IS a little more involved than some, but in compensation, its such an oft done conversion all the problems have been encountered by some-one at some point, so its a known quantity; and there are some pretty good step by step instructions for it available, (see related articles ), so you don't have to do too much head scratching. At least by what I refer to as the 'Period' conversion retaining the Series gearbox..
If you want economy; then having pondered all of the diesel alternatives; here in the UK at least; LPG conversion on top of a V8 conversion, just gives you the best of both worlds; it's as much work as any other conversion; gives as many miles per pound, and gives you probably twice the power to play with.
200/300TDi, engines...... well, read on, great engine, but NOT in a Series Land rover. If you MUST go diesel; then I'm inclined to point at the Perkins Prima.
The Series Four-Pots
OK, I'm base-lining the article with the Four Cylinder Petrol and Diesel engines, and in particular the two and a quarter litre variants. These are by far and away the most prolific of the Land Rover engines, and what most will be starting with. I know they offered the six cylinder Inlet over exhaust engine, and that the earlier four pots came in 1600 & 2.0l guises. If one of those is your starting point; well, it's not a huge leap of the imagination to consider that they share many of the vices or virtues of the 2 1/4 four pot, or to consider the added impediment or benefit that your engine has in relation to it.
So the standard 2 1/4 engine has two real weaknesses.
1 Its gutless
2 and its thirsty.
OK, they are pretty damning weaknesses, but why does the engine have them? Surely with all the resources at their disposal, Land Rover in fifty years in the game could have come up with something better? Well, what are the motors other qualities?
First of all it fits the engine bay and gearbox almost perfectly. Next, its a relatively undemanding engine, as far as maintenance is concerned. OK, it likes a de-coke now and a gain and its tappets adjusted fairly frequently, but that is the same for any old push rod engine. Practically, though, the 2.25 petrol and diesel engines are designed to work in a much wider variety of conditions and circumstances than almost anything you might want to put in its place.
The engines are thirsty, because they are not designed to get the most out of the best quality fuels. They are designed that they can be run safely on whatever low grade and possibly adulterated fuel is available in that bit of the world you are in. They are not hugely powerful, because that would make them even more thirsty, and besides, top speed is not of foremost importance in all of the conditions one may be expected to run. Motive force is more important than power, and that can be gained from lower gearing, which a Land Rover, with its high and Low range transfer box, and from torque, which the engine also has.
Which is all to do with the idea of 'matching' the engine to the installation, I have talked about in 'Motive-Megalomania!' And the Two and a Quarter, for all it's inadequacies is a damn good match for the intended installation.
And it's not just with the obvious; power and economy traded off for usability in hostile conditions or heavy load work. The engine is durable, and tolerant of poor or inadequate lubrication, again, because of low grade oils in remote parts of the world, but also because in a Land Rover, the thing might be expected to sit and run on a 45 degree side slope, and run for most of the day driving a pump or something.
Tilt a 'normal' engine over to 45 degrees, and pretty soon the sump will be starved of oil as the pump's pick up will be sitting high relative to where gravity has shifted the oil level, and the oil its shifted wont be running back down as quickly as it should, because the height is effectively lower and the path effectively longer, or what ever.
Land Rover engines can work at angles of inclination, either tilted sideways or forwards or back wards a lot greater, and for longer periods than other engines could withstand.
And then there's the matter of serviceability. Again, deliberately low tech, because if they do break down they might have to be fixed with available materials or parts, so the materials used have been kept low grade so that they are tolerant of 'cheap' fixes, like hammering a push rod straight, rather than buying a new one. Ie: push rod will bend rather than snap in the first instance, so it can be hammered straight again, and if it did snap, chances are metal spec is such that it could be brazed back together in some bush forge.
So, it all comes back to this idea of circles of optimisation. Recognise that, and recognise the engines strong points and you start to appreciate how good an engine it actually is. Might not mean that the optimisation suits you particularly well, but it may let you appreciate that the motors weren't bad by accident, there was a reason for it, and good ones. It's just that what was important to a Land Rover designer forty years ago, might not have been quite the most important things to a 'Western' user, and are almost certainly pretty irrelevant to a modern day driver.
Or are they?
I mean, Series Landies are now 'Classic' cars. The thing was designed to be user maintained under the most hostile conditions and with the most rudimentary of facilities. Great, if you were a Bush Doctor out in Africa thirty years ago, and your Local Land Rover dealer was 1000miles away, some native blacksmith could engineer a fix for you where you needed it.
Also good today, if you are a novice mechanic who wants to get into classic cars, and do all your own maintenance, with nothing more than a Halfords Socket Set and an old kitchen unit pressed into service as a work bench in your garden shed, along side the lawn mower and cans of old paint!
Which is a long winded way of saying, think hard before throwing an old Land Rover engine away, because you might be throwing the baby out with the bath water. It DOES have a lot of good qualities, and keeps things all very simple.
All you have to do, is learn to live at a slower pace, plan journey's more carefully and accept that you are going to have to pay a bit more on fuel to go the same distance.
Just as a point of note; as far as economy goes, if you read power theory, I've been quite despondent on the matter. Power = Fuel, so the only real way to save fuel is to drive slower, or cover less miles.
Land Rover is big and heavy, and to a great degree, there will never be an engine you can put into it that will give you great mpg figures. Yes, there is a big difference between the sub teen mpg's reported by people using V8's hard and the near 30mpg others claim from Turbo Diesels. But the fact remains, most of that economy or lack thereof comes from an engine that is not being asked to do the same amount of work - ie not going so fast.
And practically, human nature and psychology take over.
We will drive as far or as fast as our budget will let us. So, provided we have an engine somewhere in the middle, the economy bit wont make a huge difference to our annual running costs. If its a bit thirsty, we'll just be a bit less tempted to drive as quick or as often. If we had better economy, we'd just use the car a bit more, and drive it a bit faster, because we weren't so worried about the fuel costs.
Just as an illustration, a bloke I knew had a big V12 Jaguar. Because it was so thirsty he tended not to do too many unnecessary journeys or drive it very fast. But after about six months he was complaining. Main reason was that he'd run out of petrol on the motorway. It was a long time ago, petrol stations still had attendants, and the petrol station attendant had only filled up one of its twin tanks, when he'd asked her to 'fill it up'. More annoyingly, he'd thought 'No problem - I've got a can of petrol in the boot, I'll top it up and find a petrol station'. Only to discover that that 1 gallon can, in a 5.2l 'Double Six' didn't even get him to the next exit ramp, let alone the next petrol station!
So, he eventually traded it in for a 2.3l Granada, that he was told was a lot more economical. And it was. The sub teen Mpg he'd got out of the Jag went up to almost twenty, or more on a long run. Six months later he traded it in for another Jaguar. Because he'd spent more on fuel in those six months than he had in a year with the Jag! Simply he was no longer worried about running out of petrol, or how much he was using, he simply used the car more, so it didn't save him money. It may be irrelevant, but it does serve to illustrate the idea, of 'compensation'.
Something I always have a chuckle at is when my Gran starts telling me how economical her Nissan Micra is. She's an old age pensioner, and does something like 500 miles a year. She drives about two miles to the village post office to collect her pension and do her shopping once a fortnight, and maybe ventures out to the doctors or dentists now and then. She MIGHT drive the twenty miles to see my mum, come Christmas. It REALLY wouldn't make a big difference to her annual running costs if she had a Cadillac, but she's cautious of economy, and thinks its worth while, even though she's spending probably more a year on her tax disk, than she is on fuel.
Ultimately, its an emotive thing more than a logical one. With a 2.25, the perception that it is expensive to run is actually greater than the reality, and the perception that it is slow and under powered, similarly is greater than it actually is, simply because we don't keep up with the traffic, cant over take, and are always being over taken, and are seem to be putting an indecent few quids worth of juice in it, far to frequently.
In reality, yes fuel costs are high, but not much higher than any other similarly sized vehicle, or with any other engine.
Yes, it is slow, but again, not unduly so, and in reality, difference in real world journey times isn't always that big. Most roads are limited to 50mph ish speeds. Round town and country it isn't hugely handicapped. Its only on 60-70mph by-passes and motorways that you start to notice big differences in journey time, but the 10% difference is six minutes an hour. And that's provided you haven't been stuck in road works or stopped at a services for a coffee. It really ISN'T a HUGE handicap.
So think hard before you decide to ditch a 2.25 or six pot. They have their good points, and their bad points aren't as bad as they seem, and you may not get as big an improvement as you might hope by changing.
But read on, because going down the conversion route; might not only not give as big an improvement as you hope for, but can cost you a whole heap pf time, money and hassle into the bargain!
Conversion PrinciplesFirst of all, an engine swap is no small job. It might not be in the same league as a chassis up rebuild, but putting a non-standard engine into your Land Rover, is a 'Project' and needs careful consideration, thought and planning. See advice elsewhere on the site on that topic. But looking at what might be involved if you do, basic principle goes something like this.
You have a Land Rover, with an empty engine bay. There is a pair of chassis rails running front to back that the old engine lay on. At the back of the engine bay is the gearbox. It has a bell-housing, that is designed to bolt to a 2.25 LR engine, and a shaft that is supposed to sit inside the clutch plate and rest inside the fly wheel. At the front is the radiator, and radiator panel. Underneath, is the front axle, steering gear and the prop shaft to drive the front wheels.
So, whatever you decide to put in there is going to need to first, mate to the S3 gearbox. That may mean that a plate to bolt between the gearbox bell housing and your chosen engine is needed to 'match' the flange patterns. This is called an adapter plate or adapter ring.
The next problem is that the gearbox output shaft may now not reach the fly wheel; you might not be able to use a Series fly wheel on your chosen engine's crank shaft, or the shaft may be to big or too small to fit whatever fly wheel you have. Matching the flywheel and input shaft, and finding a suitable clutch can be a problem. There are solutions, must require heavy duty engineering, in a machine shop. I have seen fly wheels made up from cutting the centre out of a fly wheel not designed for the engine it is to be fitted to, and welding in the centre from the fly wheel that was. I've seen stepped bushes that lengthen the gearbox input shaft, and all sorts of other things like that.
BUT the point is, that with some ingenuity, its possible to match almost any engine to any gearbox
Right, Next thing, having found a way to bolt the engine to the gearbox, is to try and squeeze it into the available space. First thing is that the chances are that the bolt holes on the engine that took the engine mounts to bolt it into whatever it was designed for, wont line up with where the mounts where the original Land Rover engine was bolted to the chassis. Again, lots of possibilities exist, depending on how far away things are from each other. It may be possible for example to merely file a few holes a bit elongated to get things to line up close enough. At the other end of the scale, and probably more likely, you might have to cut the original mounts off the Land Rover chassis and make up new mounting brackets to weld in a more convenient location, and matching brackets to bolt to the engine. Again, all things are possible, it is just how much work is involved.
So, we can attach engine to gearbox, and bolt the engine to the chassis. Next question is will everything else fit around it. Longer engines may need the radiator panel moving forward, or a defender front end fitting. The other alternative is to move the engine and gearbox backwards on the chassis. Of course that would mean altering the gearbox mountings as well, and more than likely having to get different length prop shafts to get the drive from the relocated gearbox to the axles. Would probably also involve modifying the bulkhead to get the back of the bell housing, and possibly some of the engine under it, (which is actually the case with the Rover V8 conversion, even without relocating the gear-box) and cutting the floor pan and transmission tunnel to suit the new gearbox location.
But before we look at that, worth checking underneath the engine, because there, there is the axle, steering and suspension. What you don't want is the engine fouling on any of the steering gear, or the prop shaft or axle coming up and hitting the bottom of the engine when you hit a big bump. Again, infinite solutions, the engine mounts can be lifted a bit to give more clearance and tilt the engine and gearbox assembly. Like wise, sump pan can be modified to give more clearance, and the common one on V8's is that the oil filter right at the front of the engine has to be fitted on a remote housing to stop it being hit by the axle.
And at the sides, inner wings can be cut and bent to give more space where needed, and at the top the bonnet can be lifted or bulged or whatever to find room for everything. Because in and around the engine, things like the steering box, and drag link probably cant be moved, and there are bits and pieces like the catch tank for the radiator, the battery tray, air filter, wind screen washer bottle and all of that kind of stuff that you will either have to work around or find space for somewhere.
Talking about the radiator though, that is worth a mention. Standard Series, '3-Core' radiator is designed to fit at the front, and if you aren't changing or relocating the front panel, may be worth keeping. But standard Series Hoses are unlikely to line up well enough to your new engine's cooling inlets and out lets. Some ingenuity with standard hoses, clamps and bits of turned tube can solve most of these problems, but what about the cooling capacity?
I wouldn't want to rely on a 3-core radiator on anything with more than about 80bhp. For up to about 100-120bhp, I think a 4-core would be OK, but after that,. Something larger would be in order. Range Rover Radiator will just squeeze between the inner wings, but takes some ingenuity to fit, but what you might want to use is really up to you. I'd imagine that the radiator from whatever the engine was taken would be a good place to start as any. And what about the cooling fan? If you are mucking around trying to line things up, Can you still use a fan on the water pump? If you are fitting a V8, the sock fan has a very long nose and is mounted quite high. It might not be in an ideal position. Can you fit an electric fan?
And then we come to the detailing. First of all exhausts. Again, using stock pipe sections clamps and brackets, you can make up an exhaust for almost any vehicle installation. Usual problem is at the manifold, or lack there of. If you are getting a donor car out of something, make sure you get the manifolds with it, as that will save a lot of effort trying to fabricate one from scratch. You may still have to modify a stock manifold to get clearance in some installations, but like I say anything is possible. If you are fitting a Turbo Diesel, well, you should have the exhaust manifold and everything down to the turbo, and if you can get it, as much of the system beyond there too. Again, the system may need to be modified, the turbo might be located right where your chassis rail is going to sit, or something, but again, that's your starting point, and pipes can be cut and welded or bent in different directions to get clearance where you need it.
Which brings us to the other end. Hooking up clutch controls, throttle linkage, choke linkage and engine wiring.
Clutch might not be too big a problem, the original series gearbox slave cylinder and pedal box should still be useable, though depending on how you've had to move stuff, you might need a longer hose between them.
Likewise the throttle linkage. It might be possible to adapt the links in the standard Series rod arrangement to work the new engine's throttle, or find a way to graft a bowden cable between the linkage on the engine and the one on the Land Rover. Choke, cable, if applicable, like wise.
One main worry applicable to a diesel, is newer diesel engines with an electrically operated fuel shut of valve. At some point it may be possible to remove the servo assembly and fit a mechanical pull cable to kill the engine, alternatively you may need to mess around finding a suitable ignition switch and trying to replicate the wiring from the engine's donor vehicle. One simple solution may just be to have a dash board toggle switch marked 'run' & 'off' to work the engine's cut off servo, but either which way, its something to which a solution may need to be found.
Talking of wiring though, there are only a few critical connections to the engine that need to be thought about. First is the feed from the alternator. Question there is which alternator are you going to use? One from Land Rover engine, or one from donor engine's vehicle? If the latter you may need to study donor vehicles wiring diagrams to find out which terminals you need to use and where to take them. Other wise, you need the wire from the battery to the starter motor, and the feed to the starter solenoid, and the feed to the ignition system, if you have one.
Of course, if you are using a fuel injected engine, it's going to be more complicated, and you may need a fairly large chunk of the donor vehicle's wiring loom to get the various black boxes and stuff, and don't forget the fuel pump, especially if its one hidden away inside the fuel tank; and 'inertial cut out switches' which are often incorporated into fuel injected vehicles to kill the high pressure fuel pump in the event of any impact, often cause a lot of consternation!
So, last thoughts, once you have got the engine in and functional, what has it done to the weight distribution, or axle loading, and how well matched is the power curve and available gear ratio's? And if its going to go any faster, what about the brakes?
If you are using a particularly heavy engine, like one of the bigger iron block diesels then you may have loaded the front suspension enough to loose between half and an inch of suspension travel, and the extra load may give your dampers a hard time. Conversely, if you have fitted a light weight engine, then you may have gained some suspension travel, and lifted the nose of the vehicle, and effectively stiffened the suspension. You may need to investigate alternative springs and spring rates and dampers to get the ride height correct and the suspension rates in the right order.
And gearing. Series transmission is arranged to give about 5:1 overall reduction between crankshaft and axle. Which, given an engine that revs between 0 and 5000rpm, works out at 0 to 85mph in road speed, or 17mph per 1000rpm.
Standard Series engine doesn't have the power to go much faster than about 70, but, fit a more powerful engine and it might. But where a V8 might have the grunt to haul one along at 100mph, the gearing would effectively still restrict it to 85. Fit a big Diesel engine that only revs to perhaps 3500rpm, and that 5:1 reduction would see top speed limited to just 60mph, ie slower than standard. Ie: the vehicle would be 'under geared' for the engine, and it would effectively be trying to drive every where in second or third gear - so your new engine may still prove slow and thirsty!
Consequently, finding some way to increase overall drive ratio may be needed. But I'm going to look at the transmission in more detail now any way, because after thinking about the practicalities of an engine conversion, and the need for adapter plates to mate your chosen engine to a series gearbox, which has a reputation for not being the strongest, or having particularly useful ratios, you are likely to ponder the benefits to be had from a conversion that changes both engine AND transmission.
But, you get the ideas. There is quite a bit involved in an 'anything goes' conversion, even sticking to the Series Gearbox. Almost anything is possible, it's just a question of how much 'hassle' there is in and around how you go about solving each of the problems you are likely to encounter, and the compromises you are prepared to make along the way.
Which really means that its probably best to stick to the 'common' conversions, which have been done most often and most successfully and for which there are probably off the shelf solutions available for many of the problems you are likely to find
But lets look at this transmission business for a moment.
Gearboxes & Transmissions
Series Gearbox is not an extremely strong gearbox, usually on the critical path in any big mod, and it doesn't like engines that make much over 100bhp. It can handle as much as 200bhp, but the gearbox life reduces exponentially with how much power you put through it.
Just ball park: 60bhp, and it will last maybe 100,000miles relatively trouble free. 100bhp, and it may be down to lasting only 50,000miles before giving you trouble. 130bhp, and that may be down to 30,000miles, and if you try and shove 200bhp through it, well you may be looking at having to rebuild or replace the box with every oil change!
One curious thing though, is it seems more sensitive to torque than power. Hang a 130bhp Range Rover engine on one, and it can last relatively well, despite the V8 having a LOT of torque. Fit a 110bhp Tdi or big Perkins engine, though and its reckoned that the gearbox wont last more than a few hundred miles.
See my comments specifically on the TDi Conversion though, because, I have a theory that the anomaly comes down to the peculiarities of power delivery and how that can influence the peak loadings on the gears and shafts. And quoted numbers only go so far in pointing how much the box will take; Much over 100bhp it is definitely running in the margins of reliability, but actual empirical evidence suggests that 'considerate' driving and an engine with a soft power delivery can give the box a lot easier time than a less powerful motor with harsher delivery or a more 'gung-ho' driver.
Any way, obvious solution, if big power or big torque is wanted, is to use a different gearbox, and the immediate idea is the Defender or Range Rover boxes. Especially if you are pondering a Rover engine, for which there is an original equipment part number for the appropriate adapter plate to mate your chosen engine and gearbox. Even more appealing if the vehicle donating its engine to your project just happens to be a Range Rover, Discovery or 90/110 that can also give up its gearbox and other vital organs to the cause! But similarly, if you are taking an engine From a Nissan or Daihatsu, which similarly, conveniently has a four wheel drive gearbox on the end of it.
If its a gearbox, that the engine is attached to by its original maker; pretty good bet its strong enough to take the power of the attached engine; and will save an adapter kit; but Rover gearboxes can take a good deal of grunt and there are loads of people making adapter rings to mate them to all manner of engines, so even if you are contemplating say a Toyota engine, finding a kit to mate it to a Range Rover gearbox might be fairly simple..
But remember, Land Rovers, as most 4x4's have TWO gearboxes, the 'main' gearbox, but also the 'Transfer-box' which has the high and low range gears in it (though sometimes, as early Range Rover and military 101FC, the transfer is built 'in unit' i.e. as a part of the main gearbox, and is not detachable). And this throws up a whole host of new possibilities, to think about in your 'conversion', that I really don't want to get too bogged down in; but do need to look at.
Series gearbox, was taken originally from the early P-Series Rover Saloons. Its a conventional four speed gearbox, with fourth gear, actually not a gear, input and output shafts are locked together to give fixed 1:1 drive straight through it. As gearboxes go, its not a bad design, but does suffer from rather long main shafts and selection mechanisms that can get a bit sloppy with age.
Attached to the back, is the Transfer box, which was horrendously over engineered when it was first conceived, and allowed the drive from the gearbox to be split and shoved in two directions, to front and rear axles, as well as offering two reduction ratio's to give high and low range gear sets. The series transfer box, is FAR stronger than the main box, and reports suggest more than adequate of coping with the power provided by big American V8's!
I have read a number of articles of American conversions where Ford or Chevy 'Small-Block' v8 engines (around 5-6 litres in displacement, usually 2-300bhp, and even more torque than the BIG Rover V8's), with their usual gearboxes have been fitted to Land Rovers, with the Series transfer attached to the back. The only qualifier I should offer on that topic is that the engines came from American light vans, which tend to be more softly tuned and have manual gearboxes attached, rather than taken from saloon or muscle cars which would normally come with automatic transmissions, and slightly 'hotter' states of tune.
In the UK and Australia, I have read of similar conversions, retaining series transfer boxes, with adapter plates to mate them to Jaguar gearboxes, or Ford Granada gearboxes, or even Rovers own LT77, which I'll come to in a second. It is not a common way of doing things, but it is a useful way. Unfortunately, one that tends to require slightly more considered engineering, as few people offer 'kits' or off the shelf adapter plates to hang Series transfer boxes off alternative gearboxes, as they do alternative engines off series boxes.
The only 'proprietary' adapter plate I know of was offered by Ashcroft transmissions; specialists in Rover transmissions, and they offered an adapter plate to mate the Rover SD1 Saloon's LT77 gearbox to series transfer boxes. Unfortunately, they no longer offer this 'conversion', which is a shame, because it has a lot of advantages for a series converter, by way of avoiding a number of common 'difficulties' I'll come to now.
The LT77 was developed I believe for the Rover SD1 saloon, and was used in some of the last P6's, as well as finding its way into the Leyland 'Sherpa' van and a few other applications. Its a five speed gearbox, with a genuine 'over drive' fifth gear. Forth, as the Series gearbox, is a straight lock-out between input and output shafts, giving 1:1 drive through the box, however, fifth, actually 'over drives' the output shaft giving 1.25 turns of the output for one turn of input.
The LT77, is a much stronger gearbox than the series main box, and has that added ratio that does what an over drive would. And Rover decided to use it to replace the four-speed gearbox in the Range Rover, and carried that over to the 90/110, when they gave the utility models the Rangie's coiler suspension and axles.
To do so, they had to create a new transfer box to attach to it, as they had done for the original Land Rover and the P-Saloon box. The result was the LT230 Transfer box, which has been used extensively throughout the Range Rover, Discovery and 90/110/Defender ranges. These have used more LT77 gearboxes that the old Rover P6 & SD1 saloons ever did, so if you go looking for an LT77, chances are it will have an LT230 transfer already attached to it.
One thing to note, the LT230 is had more reduction than the Series transfer box, as it was designed to offer the same 'overall' reduction between engine and wheels, but with the higher ratio 3.5:1 differentials fitted to the Range Rover. There are a few different ratios available to suit different variants, but use an LT77 and LT230 with series 4.7:1 differentials and the overall top gear reduction is almost identical to that of the series transmission. Ie; the 25% overdrive afforded by the LT77's 5th gear is negated by the 25% extra reduction of the LT230.
Obviously that advantage can be gained back by using 3.5:1 differentials, or the lower gearing might be seen as an advantage, depending on your intended application. But it can be a problem, especially when contemplating the lower revving diesel engines, where they have loads of torque, which would seriously stress a series main box, but need as high a gear-set as you can get to enable that torque to be used to attain any sensible road speed from the low rev's they make it.
Other thing about the LT77, is that it provided permanent four wheel drive. it has a centre differential, and always provides drive to both axles. A lot of people mistakenly believe that the 'hi-low' lever in LT230 equipped vehicles works like the red and yellow levers in a Series, and that 4wd is not engaged until the Hi-lo lever is knocked sideways, or that selecting low, automatically engages 4wd. No; LT230 gives drive to both axles all the time, in both ranges, pushing the Hi-Lo lever sideways simply locks the centre differential, so that both axles are forced to turn at the same speed. Again, elsewhere on the site is an article that explains how 4x4 transmissions work, and the differences between the different arrangements, so I'm not going to go into it here.
As far as a series conversion is concerned, though, significance is that the series transmission is 'part time' four wheel drive, its only engaged when in low range or knock the yellow knob down in Hi-Range. In hi-range Series vehicles are normally rear wheel drive, and consequently Rover elected to use 'Universal Joints' in the front drive shafts to allow the hubs to be steered; and you can fit 'Free Wheeling Hubs' to disconnect the wheels from the drive shafts all together when not in 4wd, to improve economy a little.
Obviously, with permanent four wheel drive, FWH would not be particularly helpful, but more of a concern are the Universal Joints. When Rover designed the Range Rover, they elected to use 'Constant Velocity' joints in the front axle drive shafts to allow the hubs to be steered, rather then Universal Joints. I don't want to go into the details, again, I think I explain the differences elsewhere on the site, but Series axles do NOT like permanent four wheel drive, they do not work very well if permanently driven, particularly on tarmac, and if you do attach a permanent four wheel drive transfer box, be it an LT230, or any other from another source, it can lead to serious drive-line vibration, problems, make the steering particularly 'notchy' at low speeds and greater degrees of lock, and CAN ultimately lead to premature wear or failure, not just in the Universal joint, but in the drive shafts, prop-shafts or even the gearboxes themselves.
So, if you contemplate an alternative transmission to the Series to compliment an engine conversion, whether from the Rover parts bins, or from alternative sources, you do need to look carefully at the ratios its going to give you, and how you might get the ratios most suitable to you, which may include looking at wheel sizes as well as differential crown wheel ratios and the reduction ratios in the main and transfer boxes.
Then, if it is a permanent four wheel drive transmission, what you might do about the universal joint problem in the front axle. Unfortunately, Rover Constant Velocity joints from the Range Rover, 90/110 or Disco do not fit series axles; and if you want to retain the series axles, then you will either need a CV conversion kit, which are available though not particularly cheaply, or a Series III 'stage 1 V8' front (and possibly rear) axle, as that was fitted with CV joints, and is a direct fit to the series suspension and steering; though these are not that common, and consequently usually expensive.
A solution a lot of people consider as a quick and 'easy' answer is to use Range Rover or 90/110 axles, which have CV joints in them already, and come with 3.5:1 differential gears as well as disc brakes, and a 4" increase in track width. Taken from dead Range Rovers, they seem an ideal solution, to a lot of problems, particularly the one of money! However, the 'coiler' axles are intended to be mounted on coil spring suspension, and using coiler axles on a series Land Rover, is an involved 'conversion' in its own right, and not without some small problems, especially if you want to retain the series leaf spring suspension. If you are pondering this problem, might be worth having a look at my article Coiler Axles to Leafs.
We are at this point contemplating a fairly involved 'Hybrid' conversion, not a relatively simple 'engine' conversion, and the 'consequential' modifications from looking at the engine, have taken us all the way through the transmission, right the way to the axles and wheels and back up to the suspension and chassis!
As said; anything is possible; its just the 'worth' of doing it that is in question. Following the train through, changing the engine, main gearbox, transfer, and axles, possibly changing the suspension as the easiest method of accommodating those changes, and having to adapt the chassis to do so, stepping back, and looking at the 'whole' of the car; well, not much of the original one remains!
Certainly not enough by UK registration rules to retain the vehicles original registration and avoid re-registration as a 'rebuilt vehicle of unknown origin' requiring Single Vehicle Type approval test.
But, backing up a step; transmission conversions, as engine conversions, after looking at the actual drive train through to the axles, there are the practicalities of fitting it all up to the car. I'm NOT going to consider axle or suspension conversions, you should be getting the idea by now; but......
Having selected the gearbox and transfer box you are going to use, and devised the manner of attachment to the engine, the assembly needs to be mounted on the chassis. Just like with the engine, that will probably require fabrication or adaptation of suitable mounts.
Having bolted it to the chassis, the floor panels and transmission cover will probably need attention as they are unlikely to be the right size or shape, or have holes for the gear levers in the right place. But before looking at that problem, the gear levers or controls might need some attention to put them in a convenient or useful place for the driver to reach while driving.
Might be a simple enough case of bending the original gear lever that came with the gearbox a little, or welding an extension onto it, and being it in the right direction; maybe even cutting it down a little. In other cases it may be a bit more complicated and need a linkage made up, particularly for high & low range selection.
Of particular note, I believe that the 'remote' change assembly used on the LT77 has a number of different variants, depending on where it was sourced; be it a Discovery, Range Rover, Sherpa van or 90/110. I'm lead to believe that the most suitable for Series conversions is the remote linkage from the 90/110, but the Discovery/Range Rover remote linkage is eminently unsuitable. I cant remember whether it puts the gear stick under the bulkhead or under the seat-box, but either way, its not helpful! Other gearboxes, may obviously may have similar issues to be resolved.
However, having sorted mounting the 'box' and the controls, it's back to the floor panels and transmission cover; advice here is that for LT77/230 combinations, the floor panels and transmission cover from a 90/110 can be adapted to suit; but often as easy, or for anything else to fabricate new panels.
Useful tip here is that you can do a blue peter job with corn-flake packets, cardboard and sticky tape to get a structure made of sheet thats the right shape, then copy that, bending aluminium sheet. Thin gauge chequer-plate, I'm told is fairly easy to come by and work with and does a good job.
So lastly we have the problem of attaching gearbox to axles; which is normally done with a prop-shaft. If you are lucky, or have had the forethought when lining the engine and box on the chassis rails, you may be able to use standard length Rover prop-shafts, from the series range or other models. But it all likelihood, you will probably have to have props made up to suit the appropriate length.
Important thing is to be sure that they have adequate 'extension' in the telescope splines between the inner and outer tubes, and adequate clearance angles in the universal joint yokes so that they don't bind.
But main thing is the flange angles, and maintaining parallelity between the gearbox output shaft flanges and the diff pinion shaft flanges. If the flanges run more than three of four degrees off parallel in any part of the range of suspension travel, it can lead to horrendous drive line vibration; this can be tolerated if its at either end of the axles travel, where they don't work very often, and when they do, you are likely to be going fairly slowly; but if it occurs at or around normal ride heights then could cause significant problems, not just noise and vibration, but reliability and component failure.
Best to avoid the situation by paying close attention to parallellity when you are lining everything up; but if it comes to it, you may need a special prop-shaft making up with what are known as 'double cordon joints' in it. this a particular problem when the prop shafts are particularly short or the range of suspension travel particularly large.
Conversion Factors - Viability, Practicality & 'Livibility'
OK, hope I haven't scared you TOO much. Thing is there's a LOT to think about; and when you start looking at an 'engine conversion' all too easy to get carried away and end up going from just swapping the engine, right the way through to changing the gearbox, transfer box, axles and suspension, and having a full on hybrid project on your hands, NOT just an engine conversion.
keeping things reasonably sensible then, I think, means being quite strict and keeping the job inside realistic limits, and because of the 'knock-on's' of changing the gearbox, the conversions most likely to work, and actually provide useful benefit or gain from the effort put into them, are straight engine conversions, retaining the series gearbox
Really, how far you go, depends on what your objectives are, and what your resources to do it may be. Personally, I am very much of the mind that going much further than the bell housing, is a bad idea. I MIGHT go as far as changing the main box, retaining the Series transfer, but further than that, and it's just getting to be a huge undertaking.
Whether converting for economy or performance; your point of reference should be a 90/110/defender, whether its a V8 or Turbo Diesel. Really, if you want a land Rover with more performance or economy or both, than a series Land-Rover has, then it would be a lot easier to buy one of these to get it, than undertake a conversion. So for a conversion to make much sense, it ought to offer some advantage over simply selling on the series and buying a coil sprung Landy.
Big consideration in a conversion is normally cost, and putting it bluntly; there is no such thing as a 'cheap' conversion.
Financially, it might be possible to do an engine conversion 'on the cheap', but there is a price to pay some where. If it isn't cash out of pocket, it will be time, effort or hassle, and in all likelihood reliability and 'liveability'
And to give you a base line to work from; if you cant afford a 'decent' standard engine, whether that means overhauling a tired old knacker that's on its last legs and not giving all it should, or replacing something that's decidedly extinct with a reputable 'recon' or warranted 'exchange' engine; I REALLY don't believe that you can afford an engine conversion. And my experience has been that those people that undertake conversions hoping to get something in their engine bay that is better than standard as well as cheaper than standard, rarely achieve it.
Most conversions, to do them just 'adequately', by which I mean sufficiently well that they are functional and don't have too many compromises or flaws left in them, takes a chunk of spending that would seriously question the economic viability, EVEN if you don't factor in such things as the depreciation in vehicle value, or the time and effort of your labour, or the hidden costs of running around and supporting the 'project'.
Doing a conversion on an old leaf sprung Land-Rover, for purely financial reasons is getting less and less viable all the time, as the price and availability of coil sprung models becomes more favourable. There are FAR more 4x4's out there now, and far more affordable 4x4's, and far more affordable 4x4's with more comfort, refinement, economy or performance.
It's just that a lot of them aren't Land rovers, and in the overall, 'package' there is still 'something' about an old Land Rover, that makes it worth doing things with. And it IS a Land-Rover thing, to tinker and fiddle with them, even when it's not financially a good idea; it's all part of the 'fun'. Thing is to be aware of the 'cost' of that 'fun'.
And you ought to be fully aware of the implications of not just the financial cost of a conversion, the the performance or economy gains you might expect or the amount of effort and work needed to carry it out but the practical implications of it afterwards. 'Liveability', as a whole raft of 'stuff' to do with the day to day practicalities of living with a converted Land Rover, basically wrapped up best as the amount of 'Hassle' it is to put up with it!
How important this is depends very much on your circumstances; I mean, Land Rovers, particularly old series Land Rovers are not over endowed with 'liveability' to begin with, and in terms of 'hassle' offer an awful lot more than a more 'sensible' modern car. So, if you don't mind them being demanding of maintenance, noisy, uncivilised and having 'quirks' like windows that shake themselves open; living with the sort of added 'quirks' and hassles a conversion causes, might not be too big a deal.
But then, if you are trying to run an old Series Land Rover as an every day vehicle, that has to get you to work every day, and serve all your needs as your only car, minimising the 'hassle factor' might be quite important; if its a week-end play thing, might be pretty inconsequential.. But whichever way, Liveability is still worth some considered thought.
First of all, conversion cost. Pretty easy to tally up what its going to cost out of your pocket to undertake a conversion, But! A 'good' conversion probably wont add any value to your Landy, and a bad one will almost certainly reduce it.
Then there is the consideration of serviceability and maintenance. A lot of focus is often placed on just getting the engine to fit and work, relocating batteries, arranging clutch actuation, sorting out a suitable throttle linkage, and generally just plumbing it all in. What is often forgotten is how are you going to get in and change the oil filter, or adjust the tappets? Can you still get to the distributor cap, and things like that, which can make the car a real pain to live with in the long term.
Its in details like this, that you find the hidden cost of 'cutting corners', what seemed like a 'good idea' to effect a quick fix, and get the conversion working, often prove a right royal pain in the back-side and often demand extra expenditure later on. Typically its stupid things like exhausts that don't QUITE hang straight, and end up cracking at the welds, or cooling pipes that split because they have been stretched a bit to get them to line up; of cables that are just a tad too short or fret, that need constant adjustment or frequent replacement.
It's attention to detail, and taking that little bit of time and effort and using that little bit of extra money to do the job, 'well' rather than just 'OK' or 'it'll do', that really influence overall 'liveability'
Things like keeping all the details of the vehicle you got the engine out of, and buying a workshop manual for it, because its no good looking in your Haynes Land Rover book for the tappet clearances to be set on an engine that came out of a Ford Transit. Tip here; if you can, make sure that you see the vehicle that your donor engine came out of, and dont just write down the make and model, try and get the registration number and VIN number off it. Little things like this cost almost nothing, but when you come to order new spark plugs or an oil filter, they can save an awful lot of hassle.
It CAN be worth while, and it can be cost effective, but you have to have made clear informed decisions, and accepted the implications of what you are going to do. And it isn't as clear cut as looking at the costs, economy or performance figures.
So to look at that in a little more detail.....
Standard & Condition
'Condition' is the state an engine is in. How worn out, or tired it may be, hoe much useful life it has left in it. Standard, is the engine's specification when new. Its quoted power output, fuel consumption, and it's reputation for longevity. When you are making your decisions; don't get blinded by 'standard', remember condition is FAR more important.
A lot of engine conversions are pondered when an original engine has 'died' of old age, or is getting a bit tired. Already mentioned that if you cant afford a good standard engine, it's probably NOT a good idea to be considering an engine conversion; .an old racing adage; "Before looking for gains over 'Standard', make sure you got what you should AS 'Standard'.
The three main properties of an engine, power, economy & reliability, then the over riding property of almost everything, cost.
Power and economy are usually at odd with each other; you can have a lot of one or the other but rarely both, and generally have to accept a compromise towards one or the other. What's good for economy is usually also good for reliability, and what's good for power, is usually bad for reliability. But cost buys you as much of any of them as you wont..... though bit self defeating in the case of economy in most cases!
Comes down to common sense; but you have to look at all the competing factors in your choice of engine, and particularly so as in all probability your choice of engine will be a second hand one taken from a scrapped car or van. Using a second hand engine, it wont have its full life expectancy left in it. If you can see it in the car its to be taken out of, you may have a better chance of assessing how many miles its done, and what kind of life it has lead, and what life it might have left in it, but it is something you do need to be aware of.
If you are going to the effort and expense of converting a Land Rover to take another engine; bit pointless if that engine is only going to last a few thousand miles! And it is something that I have come across far too often.
Engine dies, so owner decides that as they have to change the engine any way, they may as well do a conversion. Working to a tight budget, they make their choice of engine almost entirely on price and performance, not how much life it might have. So, they get an engine 'cheap' maybe £50 or £100. Then they discover that they have to spend maybe £250 for adapter plates to fit it! Suddenly it's 'not so cheap' an engine! And after tallying the incidental costs, its probably mounted up a lot more.
For the same sort of money, they could almost get an exchange standard engine, with some assurance that its reasonably sound and got a fair bit of life left in it, or done a complete DIY rebuild and reconditioned the original engine, giving it a full compliment of life and reliability and probably a big chunk of performance and economy over what it had to before; saved any depreciation in the value of the vehicle and saved a load of 'liveability' issues and hassles.
Point is, beware false economy. Second hand engine is a second hand engine, and may be just as tired as what you have to begin with. If your main reason for converting is because what you have is tired or knackered, seems entirely pointless to spend a chunk of time, money and effort to stick something JUST as tired or knackered in its place as what you had to start with!
Doesn't matter HOW many BHP the book says an engine should make, or how many MPG it should give; it wont give any of either of it's seized or broken!
As a practical illustration, when I started work on Wheezil, I always intended an engine conversion. My initial thoughts centred on an SD1 2.6l straight six engine and automatic gearbox, with an LPG conversion. A bit of research knocked that on the head, and realised a full V8 and LPG would be more 'do-able'. But, then after running the four pot oil burner for a while, was attracted to a Turbo-diesel, if I wasn't going to go for an automatic transmission. However, after getting her up to a standard I could get her MOT's and useable, and putting money into overhauling the transmission suspension and brakes and fettling out the interior as a 'station wagon', I was running low on funds, and decided to back burner the conversion plans until I had save up a bit.
First major outing for the old girl, took us on holiday, with the caravan, and 17miles from home at the end, she finally died in a cloud of steam, the block boiling taking out a valve and mangling the head. Out of commission, and with a dead engine; obviously the urge to go ahead with a conversion had all the more impetus. An 'exchange' ex-military 'preserved stock' (which usually means new and unused, or reconditioned and mothballed) Diesel engine, at the time would have cost about £600.
With that as a base line, a 'take out' V8 from a Range Rover, would have set me back about £200, for something in reasonable shape. Add to that £180 for an adapter ring to hang it on the series gearbox, and another £40 for mounting brackets, and it's still looking reasonable. But, add incidental costs, new exhaust system, getting the foot-wells cut back, and then hoses, clamps and cables and such to hook it all up, and it's getting a bit tight. Add an LPG kit and I'd have broken the budget by a very long margin. Realistically, to do the job 'justice' even without an LPG kit, I was looking at having to spend the thick end of a grand.
I might have been able to save a few quid using a cheaper engine, and trying to find a second hand adapter kit and LPG kit; but however you try and crack it; JUST getting an alternative engine in there, and serviceable, was going to cost me damn near as much as a known condition exchange lump; with almost full service life in it.
Now, a V8 conversion is one of the more involved, and so not the 'cheapest'. But, when you read the comparisons, it isn't THAT much more involved or expensive that the alternatives. And, to be honest, in a lot of cases I know for a fact that it's actually a lot cheaper.
But, if you check other bits of the site, you will see that I did a full DIY teardown and rebuild of Bert's V8, and it cost me all up about £700. Given that that was a V8, with twice the number of cylinders and cylinder heads to be fixed and fettled, I would expect to be able to do a similar job, to a similar standard on a four pot for considerably less, probably £400-£500. Which would have been a saving over an exchange engine, and probably less work than a conversion.
As it was, at the time, my budget was incredibly restricted, and I would have been stretched to find even that. Consequently, I sourced a second hand 'take out' 2.25, which I think cost me about £150 to get into the engine bay and working. It didn't stretch the budget, and left me room to sort any 'hassles' I might find, and minimised the hassles I was likely to find; and practically bought me an engine with as much life as I could have reasonably expected to find in a similarly second hand V8, possibly a little more.
V8 idea wasn't abandoned; but I knew that it isn't viable to attempt it until I had the money to do the job and do it well. I had bought a cheap 'sensible' car, an old Montego estate, as a commuter & runabout, which meant that I could have tolerated a bit less liveability from Wheezil, as a 'leisure' vehicle for family outings, day trips, and household 'chores'. But she still had to be reasonably hassle free; and i valued 'livability' and reliability as being reasonably important. And unless the time, resources, and funds are there to do the job and do the job properly, I REALLY believe that a conversion will simply buy you more heart-ache and hassle than its worth, and NOT significantly save you any pennies.
And although I never actually got as far as converting Wheezil, family 'difficulties' mentioned elsewhere on the site, changing circumstances, I did get as far as procuring the V8 for the job; actually a by-product of Berts boiling his block..... but having acquired a 'cheap' take out to keep him in service while I reconditioned his original engine, after transplanting that back in, the intention was to do likewise to the 'take-out', add LPG and fit it to Wheelzil. Important thing though, was that the conversion engine, would effectively have been fully reconditioned, and that alone would have made it more expensive than a reconditioned exchange, standard unit.
Done to such a 'standard' that offered the same kind of reliability as I could expect from a recon exchange four pot, it would NOT, by any stretch of the imagination, have been a 'cheap' conversion. And THAT is the nub; of the matter in making comparisons; be aware where you are or aren't comparing like 'standards'. A conversion might be cheap, but it's 'value' depends not just on how much performance or economy you get, but how much of either you get in relation to the 'life' in the motor, the reliability of that motor and how much hassle it is to live with.
And, having pointed out, that the comparison for a conversion should be a coil sprung Land-Rover; here's the quandary; if you take 'condition' into account; doing a 'budget' conversion using a second hand engine, in all likelihood, will cost you more than trading your series Landy in for a coiler; and in all likelihood, you would get a better condition of coil-sprung Land-Rover for your money, at that end of the spectrum.
Other end of the spectrum; doing a conversion, and not sparing the expense to do it well; and as I intended, using a reconditioned engine; the condition of vehicle you get for your money and effort will probably be a lot better, than you could get for equivalent spend part exchanging your series in for a 90/110 or defender.
In Wheezil's case; I had spent about £350 doing a DIY rebuild on the gearbox; I would have spent about £700 reconditioning the 'spare' V8 for her. Fettling that engine in, would probably have cost me the best part of a grand, with an LPG kit, probably £1500. I had spent, something like another £2,500 or so, on the rest of the car, fitting parabolic suspension & gas dampers, overhauling the brakes, putting on decent tyres on nice new modulars; and doing the 'county' conversion, entire interior; ten seats; belts trim, was all brand new.
So, for around Five grand, I would have had a 'converted' Series III Land Rover, that was 80% a brand new car! Economically, I would have been VERY hard pressed to find a 110, of similar condition, for that kind of money. Mean while, I could do the jobs that needed doing, or that I wanted to do, as and when funds allowed; And I actually ENJOYED doing those jobs.
So, conversions can be worth while; they can prove economical, if not 'cheap', and they can have advantages that are beyond just the money or hassle; thing is, you HAVE to be aware of what you are getting into, and have a pretty clear idea of what you hope to achieve, and what it's going to take to achieve it.
So, lets look at my 'usual suspects' the six common conversions, I've pulled out to use as bench-marks for evaluating any other alternatives.
Land Rover 2.5 NAD or 2.5Td
First of them is to use a Land Rover 2.5Td from an early Turbo Diesel Defender, or I believe the larger 'double-wheel' Sherpa vans.. Reason that I put this one right at the top of the list, is that it seems to offer the biggest performance and economy gains for least effort or conversion hassle. The Td engine has a reputation for being a bit weak, but if you get a good one, or rebuild before installation, should offer pretty good reliability.
It makes about 85-90bhp, which is as much as a stage 1 V8, and more than enough to make a Series Landy 'useful' without seriously stressing its transmission or running gear. Economy wise, potential to be in the high twenties and into the low thirties, puts it at the upper end of the scale, though using the available power hard, could see it dip into the mid twenties. Still, its better than the 2.25P by a long way.
As for fitting one, well the 2.5 engine's block is common to the 2.25 5-brg engine used in the last of the line S3's, and early 90/110's. Basically, the differences are inside and at the front. I'm not too certain about the shape of the sump, but as far as I know, the thing goes into a series Landy pretty easily.
Box goes straight on, with no need for an adapter ring, change of fly wheel or anything, and about the only thing that may cause hassle is the engine mounts - and I think that the series Landy's battery tray is in the way, which are hardly insurmountable difficulties. Which basically means that it needs the least specialist conversion adaptation of anything else you might think about fitting.
Weights also match pretty closely, so it shouldn't need any suspension mods, and the engines power curve and rev range pretty well match the original, it just makes more power, so the gearing shouldn't be too far off. With an overdrive, probably being about enough to get a bit more speed from the extra power or drop the cruising revs back a bit.
Many thanks to a forum user, Stuart Cane, who has done this conversion on his Series II, and who provided a photo-blog of it for the site, 'TDing a Series II', that provides a little more insight.
Only real bug bear I can foresee with this one is the cost of finding / building a decent engine. It's rather maligned engine, they have a reputation for going wrong, which is mainly down to Leyland build quality of that era, and I suspect, user abuse and poor maintenance. And given a rebuild, I think that most of the concerns about these engines could be eliminated.
This was my 'proffered' choice at one point, for Wheezil, and centred on doing a full tear down and rebuild of the engine before installing it. That precaution, in my case demanded sourcing THREE donor engines to get all the parts I would have needed, as it seems that few of these are lying around in one piece in a functional condition!
I think with this engine, that that is probably prudent to be assured of any realistic kind of reliability; so its a conversion that would have to be done 'properly' to a high standard, to be worth doing at all.
Intercooler upgrades are reported to work well, but I suspect coupled with timing pump mods to get more power may account for a lot of piston failures, which have a reputation for cracking any way, though a rebore may necessitate them any way, I envisaged replacing as course and possibly upgrading with 'hepolite' or similar items. And I also looked into the possibility of upgrading the oil system, with an external oil cooler, and a pressurised plenum for the turbo supply, to improve blower reliability, which seemed sensible.
The 2.5NAD, was used in the early 90 & 110, as well as the Sherpa van, and is basically the same engine as the 2.5Td, but without the turbo. Internally there are differences in the camshafts, pistons and cylinder head; so you cant attach the turbo plumbing from the outside of a TD to an NAD.... well you CAN, in fact bolts straight up..... just probably go bang rather more quickly than a Td engine!
There are slight variations between the Sharpa and 90/110 variant engines, but basically either will fit into a series pretty easily as the Turbo variant, without so much plumbing to worry about. And plenty of people have fitted them. They don't have as much performance; they make about 70bhp, and are about on a par wit the 2.25 Petrol engine.
They don't have the reliability problems the Turbo charged engines had, though they are probably pushing twenty years old by now, so their reliability will mainly depend on condition.
Of all the possible conversions; the 2.5NAD is probably about the 'easiest' be it for the cost or effort of fitting it; or living with it afterwards. but the performance and economy gains are similarly small.
It is basically a 2.25 Diesel engine; and as close to a direct replacement as you can get. On a limited budget; this is one of the few conversions that can be done 'on the cheap' as it is more of a straight replacement than a full 'conversion'.
The Rover V8
This is a much loved conversion. That engine is just pure class. It sounds lovely, and makes its power so subtly it just oozes charm. Practically, it is about as far as you should really dare go on a Series Gear box. And then only after fully over hauling it. The power and low down torque are pretty phenomenal, its about as punchy as you can get an engine to be. If you want power, and speed, then this is a good choice. Only problem with it is the fuel bill. Or is it?
MPG can be in single figures if one of these is set up badly or used hard. But a gas conversion is possible to let them run on LPG, and while it does nothing for MPG figures, at least takes the sting out of your wallet to live with the poor MPG it has.
And, with Diesel now heading perilously close to the pound a litre threshold, and LPG still readily available for about 45p a litre, miles per pound, a 'Gassed' V8 could be as cheap to run as a Diesel, and offer a heck of a lot more performance to boot.
Interesting to note that the 3.5V8, in all but strangled Stage 1 form, makes more power and more torque at every engine rpm than a 200Tdi, and taking back to back MPG figures for each engine, fitted to the Disco, Tdi returned 23-32mpg; V8 returned 14-20mpg. if we say Diesel is £1 a Litre, and, and LPG is 50p a litre, Tdi would give between 5 & 7miles per £, while the V8 would give between 6 & 9! Ie: a gassed V8, would be something like 30% cheaper to run than an oil burner! That has GOT to be worth considering!
Supply of V8's is pretty good, with many ripped out of Range Rovers, either when they have died or been converted to Diesel power, and so are not that hard to come by or expensive to acquire. And they are VERY well supported. Not only do they have the advantage of being a genuine Land rover engine, so parts can be obtained though the 'usual' sources, the engine has been so widely used by specialists for sports cars like the, Morgan and TVR, and is a favourite amongst the Custom & Kit-car fraternities. Parts, tuning goodies and people experienced with them is all readily and locally available and second to almost no other engine you might want to consider - well, unless you're considering an Austin 'A' series 1275 'Mini' engine, and I doubt that very much!
And its a very practical consideration, when you consider that for many, but particularly Daihatsu motors, you cant get a service manual or buy spares without quoting the chassis number of the donor vehicle the engine came from, and there aren't that many people that are experts with them. Show a Landy mechanic one in a Series 3 engine bay, and he'd be as likely to be able to do anything with it as if you'd driven in the Four-track it came out of. Show him a V8 though, and he'll be in his element!
Any way, it's a good idea to do a tear down, or at least a partial tear down, before trying to use a second hand V8 engine. They are a very durable unit, described as 'low stressed', which means that they don't work hard to make their power, and will often run up huge mileages without problem. Unfortunately, that does lead to some owner neglect, and they have a tendency to get gummed up, and most benefit from a bit of decarburising - particularly in the valley of the V where the cam and tappets are! Advice on that mater is dealt with in various other articles on here.
But the essential message is that the V8 has an awful lot going for it - remember, its a Land Rover engine, so has many of the virus that the Series engines do as far as operating conditions, durability, reliability and support, plus some. Only thing is, fitting one in a Series engine bay and to a Series gearbox, isn't quite as straight forward as the 19J 2.5 Td engine, but then few of the possible alternatives are.
V8's need an engine back plate or conversion ring to be fitted to the Series gearbox, but these are widely available, alternative engine mountings are needed and there's some fiddling with the clutch necessary.
Next two main things are that he bulkhead and foot-wells have to be cut back a bit to clear the rear cylinders, and the oil filter needs some attention to avoid it fouling the front axle.
As far as installation effort goes, this is probably not a lot more involved than any others, and as its a well trodden path and been done so often before there are a lot of people with a lot of experience of it, and the bits and know how are all there and waiting to be used, which is not necessarily true of many of the alternatives. Three articles on this site deal with the conversion in more detail:- V8 Conversion; Dropping in a V8; V8 into Light-weight; the last two magazine article clippings providing almost step by step instructions of what you need to do, including things like clutch part numbers!
Of ALL the conversions I've considered here, and of all the alternatives I have ever looked at; the Rover V8 conversion stands out a mile; seems a really crazy idea to try and hang such a monster of a motor on a series gearbox; but when you look at it, it actually makes a LOT of sense!
If you are going to go to the cost and effort of conversion; you might as well get as much out of it as you can; and THAT is what the RV8 offers; and given that it is NOT that expensive, and all the 'problems' so well known, its actually a lot 'safer' than many. And I really do think that it needs a lot of very serious consideration: IF you want a different engine in your Series Landy, to the one put there in Lode Lane, whether you are primarily concerned with wanting more power, or wanting more economy, the V8, on gas, takes some beating on either count, and if the work or cost involved in doing this conversion is an issue, then REALLY you probably ought not be looking at a conversion at all!
As I mentioned at the beginning; whether converting for economy or for power; THIS is the one I keep coming back to as my recommendation; and the one I think should be used as the main bench mark for anything else.
The Rover 200/300Tdi
Had LOTS of discussions with various people on this one; TeDiouse people argue that the engine is great; best Land rover have ever made, rugged, reliable & powerful...... and then LIE and tell you that there is absolutely NO WAY that it is the engine's fault that the Series gearbox inevitably breaks;
One particular casualty, having shown pictures of his Fairy Over drive with the CASING in two pieces, swore blind that the failure; three weeks after fitting a TDi, was in NO WAY related! Sorry, but Fairy Over Drive Units do not shear across the flange after sitting on the back of the transfer box for twenty seven years unless SOMETHING has over stressed them! Cogs may grind, bearings may whine, they may even refuse to stay in mesh, as they get old, tired and worn out; wear and tear does NOT smash castings! TDi Engines though DO!
Pundits argue that the TDi makes less power than a V8, so if a series box will take 150bhp of Buick muscle, then they should cope with a paltry 110 Solihul pit ponies! But then they also argue that the TDi has more torque than a V8...... Hmmmmmm Series boxes are torque sensitive..... look at how the REALLY high torque 3.0l Perkins kill them...... any connection here?
But they are still lying, because TDi's do NOT make more torque than a V8, even as commonly claimed 'low down'. I pulled some charts recently; and I couldn't find a genuine TDi Dyno curve, I had to make do with a 2.8TDV 'High Torque' version....... that MIGHT given a bit of dyno inaccuracy have, for a couple of hundred RPM around 2000rpm, a ft-lb or so more torque than a V8....... but most of the time it came no-where near. And low down? Well, TDi's trace started at something pretty paltry, like 70-80ft-lb, and ramped steeply to a peak of 160ft-lb at 2000rpm.
V8? ......... do you REALLY want to know? It will make you cry! OK! It STARTED at 160! and then lazily climbed to a peak of about 220, around 2500rpm! Yeah; like exactly WHERE? Is all this 'Low Down' Torque they claim that the TDi has?!?! V8's got more torque at TICK-OVER than the TDi has as PEAK!
Right V8; long flat torque trace, over 5000rpm 'useable' rev range; varies by only 40ft-lb or so from tick-over to peak, with no steep gradients in the graph any where. TDi: North face of the eiger shaped profile from tick-over to peak. HUGE gradient as the torque ramps up and more than doubles in about 1400rpm!. Only has a 4000rpm useable rev range, so that compresses the trace making it effectively even steeper.
Now, this is where we have to make a leap and forget the RPM scale on the bottom of the chart; What we are interested in 'Rate of change of torque' or how the engine loads the transmission; so we need a 'time' base, not a distance one. RPM's I know are speeds, but we are interested in how fast the engine changes engine speed, not what engine speed its doing.
Unfortunately We don't have a time base,; so we have to do a bit of comparing and make some inferences. First of all, gear change points, you use the engine's most willing 'power band' between changes. Diesel has a narrower power band, because it first has a more 'spiky' power delivery, and second, it has a smaller useable rev range. NEXT Diesels don't rev as 'willingly' as V8's.
So, a little bit of pro and a little bit of con. In use, TDi wont rev up as quickly, but it has a shorter rev range to cover; so ball park, we can presume that as a time base, we could stretch the diesels dynio trace to perhaps double, to get a similar sort of time base between engine speeds on the bottom axis.
So, from tick-over to 2000rpm, the TDi might take twice as long to apply the load it does, BUT, where the V8 has increased applied torque by barely 25%, in the same time, TDi has increased torque by double that. Ie; the TDi's POWER DELIVERY, even with some generous 'allowances' is hammering the proverbial out of the box by how 'hard' it ramps the power onto it.
It's 8-Stone women in stilettos vs Elephants on dustbin sized feet kind of loadings; it's not the actual mass, its the destructive pressure they apply; and the way that the TDi delivers its power is very hard, generating VERY high peak loadings on the cogs, which isn't good.
I reckon that that OD unit went because the peak loadings on the cogs was enough when the gears were under load to generate enough 'stand off' thrust, pushing the cogs apart that the OD unit was being 'waggled' on it's flange, stressing the case and setting up a fatigue fracture; certainly the pics of the lesion had all the tell tales of a 'fast fracture' through fatigue stress.
The 'box itself was reputed to have been a 'good'n, having been reconditioned before being mated to the TDi; a lot of failures reported; often shattered lay shafts, would seem to be a born of the same failure mechanism. Main shafts seem to have a slightly easier time, because they aren't that well supported, and the bushing between them, I think, especially as it wears, gives some compliance allowing the cogs to 'stand off' a bit, BUT, then you get accelerated tip wear, and eventually the loading on the teeth on the lay-shaft causes them to fatigue, then crack at the base of the tooth, and when its grown to critical length, go by fast fracture through the cast shaft.
It's pretty much what 4203 Perkies do to them, only in that engines case, its even worse as it has an even narrower power band, and even more torque, and the only saving grace is that the thing is about ten times more reluctant to change engine speed!
Conclusion; Series Transmissions DO NOT LIKE Tdi engines!!!!!!!! However you argue the numbers!
If you beef up the box; and by that I would say Suffix D Main box, fully reconditioned, with NEW lay-shaft and preferably undercut cogs. Ashcroft Hi-Ratio X-fer conversion instead of an over drive, to get the gear set up and keep the 4.7:1 diffs so that as far as possible the power is being delivered to the axles as revs not torque.
I would want to fettle my props, with new yokes, and if I could some prep work on the spiders to stress relieve them; THEN I would have them professionally balanced to racing standards to avoid vibration resonance.
Last up, half & quarter shafts; Rear Salisbury would be essential, but with up rated halfers; and I cant remember whether there is a tougher diff to go in that, but if so, use it, or that TDi engine WILL find the 'weakest link' sooner or later; they knock out the diff spiders in Rover diffs if you have belt and braces'd everything elce.
Lastly; I'd treat it VERY gently, and DELIBERATELY accelerate slowly, without opening the throttle all the way.
Some have asked about turning down the boost, or 'detuning' it with the injector pump; end of the day it's not the amount of power that's dong the damage, its how hard its delivered; so unless you go right the way back and re-cam it, re-map it and re-size the blower to suit, you wont get much 'softer' power delivery, and if you DID, you'd probably be spending a lot of money to get something less useable than a prima...... so considerate right boot! And maintenance.
Not so much a question of how do you AVOID a TDi killing a series transmission; more a case of how do you take the longest rout to it getting there! So far, on well fettles mechanicals, some are bearing up OK; best one I know of has managed something over 30,000 miles continental touring! BUT; it was a VERY carefully prepared example, very considerately driven.
Most I've come across have been ripped from rotten Disco's at about 150 thousand miles then; thrown at an untouched 25+ year old, and probably 1/4million mile Series gearboxes, with varying degrees of care or prudence. Most have usually gone 'bang' in well under a year, and if they have got more than 5000miles then they have been doing well.
If you REALLY want a TDi in your series; fine; go for it; but its twixt you and your conscience as to how much you want to torture your tranny! Or how fond you are of removing the seat box and doors, or course. If you go for it; while you're down there; fit a military bolt on cross-member.......... will probably come in VERY useful!
Economically and Practically; yeah, VERY appealing conversion. engines are now 'reasonably' priced, and you can get a 200TDi 'Take-out' from a rotten Discovery for about £500, which will fit to a series bell housing without an adapter kit, and which will drop onto the chassis rails with I think adapted Defender mounting brackets; There's a few issues of clearance and turbo location, that I think again can be sorted using stock LR parts, so on the face if it it does NOT look a very demanding conversion; and the costs are certainly attractive.
BUT, that transmission will punish you, if you are at all cavalier about it; and if you don't recondition everything before you start loading it with TDi power, you will probably have a lat of halts to do so as you go along, and each 'weak-link' is found in turn.
Take THAT into account, and this is one conversion, PERSONALLY I would be very cautious about undertaking. It's ONLY 'cheap' because the engine's not that expensive and it doesn't need an adapter; engine itself is likely not to be hugely endowed with a surfeit of remaining service life; but even it will soon diminish what's left in the rest of the vehicle.
As ever; if its worth doing, its worth doing properly, and in this case, doing it properly would ultimately be a lot more involved and expensive than a V8 conversion; and NOT deliver the rewards for it in anything LIKE reasonable measure. The TDi's reputed 'economy' certainly wouldn't be significant recompense I don't think.
Perkins 'Prima', Montego Engine
One of the most vaunted and popular conversion of the moment, is the Perkins, 'Prima' or Rover Montego Turbo Diesel engine. Personally I like this conversion. The engine is a belting little unit, a bit lighter and a lot livelier than the Land Rover engines, chucks out a healthy 90bhp, and can offer mid 30's mpg figures. Some people even reckon they see figures heading towards the 40's. And I can believe it.
The one thing this engine lacks is strong low rev torque. Some argue that that makes it not particularly good for off roading, but looking at the figures I've seen, its not that far off. Compared to a 2.25 Diesel, yes, bottom end torque suffers, compared to a 2.25 Petrol, its only a bit down. Unless you are trying to plough a field, I honestly don't think it would actually be a big problem.
The engine itself is renowned for it's endurance, examples regularly racking up quarter million mileages in Montego Taxis, with little more than regular servicing. Conveniently, Montego's rot or fall to pieces before many get the chance to go that far, hence plenty of donors with engines with lots of life still in them, but they are pretty sought after
At least at the moment. My only reservations about this conversion, is that the Montego went out of production about ten years ago, so the supply of donors is starting to dwindle. Then, it is a car engine, so while it might be durable running around the back streets of Brum, I'm not so sure how happy it would be being tilted all over the place on tricky climbs and traverses, and not starving any part of it of oil. And the last BIG one, Austin Rover have gone bust, and the support and back up you might expect for an engine from another donor, might just not be there for a Montego engine very much longer. But, it was built by Perkins and used in other applications, so it will be there, only I'd imagine it being a bit more difficult and a question of needing to know the right specialists.
It has better economy than just about anything of the potential conversion candidates, and STILL has more power than a Stage 1 V8, and it is reputedly a cheap and easy conversion, so on a tighter budget, it does have some advantages over other alternatives.
Fitting one, is certainly easier than a V8, and not a lot more involved than the 2.5TD. Adapter plates are readily available, and the clutch/fly wheel problem is avoided using a standard fly wheel from a Sherpa van. This is about the only difficult bit to source and breakers are now sometimes asking silly money for them. Engine mounts are easily fabricated or are available off the shelf and the only other major thing to worry about is a bracket to re-locate the alternator.
All told, they reckon that this conversion can be undertaken and completed using available parts, leaving you no fabrication work, just old fashioned spannering, for under £700, including the purchase of a road worthy, taxed & MOT'd Montego as the donor for the engine.
On my rough reckoner that if you cant afford a decent 'standard' engine you shouldn't be contemplating a conversion; this one is just about on the threshold. If you are prepared to hacksaw file and weld, then they claim that this conversion can almost be done for 'next to nothing'. Which is a bit subjective, but given a £100 for a Montego, and a few quid here and there to get things you cant make, and then breaking up and selling on parts from the Montego, I suppose it is feasible you could break even - more so if you were to have a good LR engine that could be sold on as well.
Practically, this conversion is probably well within the scope of the typical 'hobby' mechanic's time, facilities and skills, not requiring any major fabrication or modification of associated bits.
The original conversion kit was offered by Dudliegh Engineering, who have a lot more info on their web-site, both the parts and kits they make and supply as well as example conversions and owners reports etc. Another person offering adapter plates and parts is a very industrious chap chap called Richard masquerading on the Forums as 'Integerspin'. He made his own adapter pieces and offers to help others do likewise, or again make and supply bits for them. He has a site at, www.integerspin.co.uk. And if you want to know even more, then another LROi forum bod, going by the handle 'yojimbo' set up a Prima Conversion Forum, where you can go look for necessary bits and advice.
As the Rover V8 conversion; it has a lot going for it by way of it being a well trodden path. The problems and hassles are all well known, and documented, and again, almost step by step, 'how to' instructions are available for it. And recently I found a magazine clipping article, detailing a conversion to an 86" Series I, that is pretty comprehensive, and have added to the site as 'Fitting a Prima'.
Pushed to recommend a Diesel conversion, or a conversion to do on a limited budget, this is would be my choice. It is NOT a conversion I would do personally, I would rather spend the little extra and put in that bit more work to do a V8 conversion, for the greater gains; and when I considered Diesel conversions, I plumped for the Land Rover 2.5Td; but with a fully reconditioned engine; which for most would probably price the conversion out of realistic limits.
For many though, this is a very 'do-able' conversion, that offers enough reward for the effort involved, at the sort of costs that are bearable, and is plenty easy enough to live with afterwards.
Ford Granada 2.8/3.0 V6
Ford Granada 2.8/3.0 V6. These days you can probably discount the 3.0 'Essex' engine. In some ways it was preferred to the 2.8l 'Cologne' block, and ran a carburettor where the 2.8 was normally fuel injected, but I don't think that they have made an Essex since the mid seventies now, so possibly difficult to actually go looking for, and if you did find one, likely to need a complete rebuild. 2.8's have been fitted to Granada's and the like for years though, and I think that they are now 2.9l, and pretty common place.
Like the V8, the conversion is a fairly involved one, but again, the conversion is fairly well tried and tested, and there's quite a bit of experience and support around for the Ford V6, though no where near as much as for the Rover V8. Another one I have found a 'how-to' magazine clipping article for, which I've added to the site, as, 'Fitting a Ford V6 .
The main advantage of the V6 used to be that it was a more compact unit, being shorter and narrower than the V8, so it fitted in the engine bay a bit more easily, and when Ford Granada's outnumbered Range Rovers in the scrap yard, it was much more readily available, and cheaper unit to get hold of. Though this is not so true today, and it's probably easier to lay your hands on a Range Rover engine now.
Consequently I'm no so convinced that the V6 has much, if anything to offer over a V8 any more, to be honest. It might be a little easier to fit into a Land Rover, but in the scheme of things, the difference isn't huge, in terms of effort. Not having to cut back the bulkhead, puts it more within the realms of possibility for the average hobby mechanic, who could do the conversion on their own drive, and isn't confident about their welding and metal fabrication skills, but getting a professional to do that bit of a V8 conversion wouldn't be to expensive, and the benefits of the V8 would I think make it worth while.
Like the V8 it's still a bit thirsty, though again, conversion to LPG is possible, but again far better support for LPG converted V8's. Power wise, its a strong motor, though its not got he lazy torque of the V8, and its a bit rev happy. Again, coming from a car, it's 'hostile environment' durability is questionable, though many V6's have seen competition use without too many complaints.
In summary a 'typical' conversion. A bit long in the tooth these days, but still has some benefits to offer. Cost wise, Granada engines are not that expensive in the scrap yards, and the cost of an adapter ring and engine mounts is about on a par as for anything else, and on a budget its quite a realistic and practical conversion to undertake.
But compared to a V8, I think it is a bit of a poor-mans choice, and while it may be pretty good, be just that bit disappointing, when you could have so much more for just a little bit more effort. While livability wise; it's slightly more handicapped, coming from a different manufacturer.
Ford/Peugot 2.3/2.5TD Transit engine
Ford Diesels never enjoyed a good reputation up until about ten years ago, they were always under powered, woeful of economy, and worse, unreliable. They seem better these days, and I think that there is a tie in with Peugeot somewhere along the lines, as they seem to share engines.
The 2.3/2.5TD I think is used in a number of vehicles from the Sierra through to the transit van, in turbo and normally aspirated form. As well as being common to a number of Peugeot and Citroen, and possibly Renault and other makers offerings. Personally I wouldn't bother with the non turbo variants. The Turbo Diesels have all the extra power for very little extra installation hassle, and very little loss of economy, in fact the TD's are often more economical.
Any way, the veritable old 'Tranny' engine is reputed to be a tough old lump and generally pretty tolerant of neglect and abuse. Which, in transits it tends to get in abundance, which is one reason I would try and source a motor from a different donor if I could! Makes about 90bhp, like the Prima and LR 2.5TD, with good bottom end torque. Being a Ford, parts are cheap and available for servicing, and the only criticism I've heard of for the motor is that it is very noisy and uncivilised.
Peculiarity of Transit engines; they seem to struggle on seemingly on their last legs for years and years, refusing to die; but all of a sudden, a seemingly 'good' one will just turn belly up without warning!
Like the other conversions, you need an adapter to mate the engine to the Series gearbox, engine mounts etc. But, it doesn't need any major fabrication work, like the V8, or some of the six cylinder or very large Diesel alternatives. so again, well within the scope of an average amateur mechanic.
It's at the bottom of the list though, because I reckon that for the expense of conversion, you would be better off trying to source a good LR 2.5TD, which is probably as good, and easier to fit, BUT, in the pro's and cons, if the budget's tight, these engines are durable, and if you don't have the money, time or expertise to rebuild a Landy Lump, then a Peugot/ford engine, you can get cheaply and not have to fiddle with, could be a the next best thing.
Livability seems reasonable with them, they aren't entirely hassle free, but access around the engine is pretty good, and they don't seem to need much attention; but again, they aren't intended for 4x4 installation so possibly not as tolerant of extraordinary operating conditions; but then probably better than many, if you seen the places a lot of builders manage to get flat bed transits!
So that is my top six. There are plenty of other options. Perkins engines and Daihatsu engines being some of the more common alternatives, but of the alternatives, I think that these probably set the benchmark by which the others should be judged.
All of them take some amount of 'crafting' to make them fit. All but the Land Rover 2.5 NAD & TD, need adapter rings, alternative engine mounts and some mucking around with the clutch, if nothing more. the V8 needs the bulkhead cutting back for clearance, which is a problem shared with other V8's and 'big' diesel engines.
These conversions, though, are all well tried and tested, and the niggles, gripes and 'problems' that you might find along the way are all pretty well known about, and well recorded and there should be plenty of advice as to how to sort them out, and the engines are all similarly well tried, tested and proven.
All offer an appreciable performance boost over a standard Series engine, and the diesels at least, potentially offer some modicum of economy, though LPG on a petrol, engine, even a two and a quarter, can probably better the miles per £ of the diesels.
But lets have a quick look at he economics of it. There is a 'minimum' threshold of time and effort that you'll have to put into any conversion. Ball park, conversion kits tend to be in the order of £300ish. The more you fabricate yourself, the less you'll have to buy, but even so, it puts it into context.
As said, really, there is no such thing as a 'cheap' conversion; and my advice is that if you cant afford to get a 'decent' standard engine, by fettling or replacing what you have; then you probably ought not to be considering a conversion.
The cheapest of conversions is the 2.5NAD; which really isn't a conversion, unless you are swapping it for a 2.25Petrol, because it is basically an updated 2.25 engine. Gains to be found from it are fairly small; but then the effort of 'converting' is likewise pretty small. And on a tight budget, really is the more sensible choice if you want a bit more than a 2.25 has to offer.
Perkins Prima; I am NOT convinced is as cheap as is claimed to fit in a series Land Rover; but it is still reasonably cheap to do; and a very close call between reconditioning or replacing a standard engine with reputable warranted like for like replacement; though must be remembered, donor will be a second hand and probably well used engine, and not got all the life a direct replacement would have. Does offer a useful amount of extra performance and a good deal of economy though.
Rover V8 keeps coming out as my preferred conversion, for the simple reason that it offers most bang for your buck, and if you are going to the hassle and effort of a conversion, you might as well go the whole hog, and get as much out of it as you can. And that's what the V8 offers in spades. And its drink problem can be tamed with LPG.
And economically, its actually NOT that expensive. Basics of Adapter and mounts are no more than other conversions require; likewise sorting the exhaust system and plumbing and fettling. Adapting the bulkhead is an added hassle many conversions don't present; but its not a huge one; and overall, the liveability and 'risk' associated with the conversion are not that bad at all.
Main thing with the Rover V8 conversion is that Range Rover engines are pretty plentiful, and often pretty darn cheap. I paid just £70 for the runner that I dropped into Bert while I rebuilt his original. Practically, if you decide to ignore my advice over not contemplating a conversion of you cant afford a decent standard engine, you COULD do a Rover V8 conversion on the cheap; but, given that the engines are so cheap, you could use the savings to do the job justice and do it well, which would give you something a lot more 'livable'.
I have not included any of the Japanese conversions for comparison; they used to be a 'cheap' alternative to a TDi conversion for a Range Rover or 90/110, and as pointed out, I really don't think that the TDi is a good match in a series Land-Rover, certainly not with the series gearbox, and going beyond that, makes the conversion, even more questionable.
I do want to mention the Japanese Diesels though. Daihatsu I have commented on, with regard to liveability, they are very difficult to get technical data on or spare parts; and I have come across a number of people that have acquired Series Lanies with them already fitted, and found that when they have got a bit tired they are a nightmare; and they have ripped them out in disgust, and had a double quandary of what to put in their place; another Daihatsu, another conversion, or converting back to standard!
Thing with all the Japanese Diesels, though seems to be that few of them are particularly free revving; most of those that make respectable power are hard on series transmissions, they nearly all need more gearing than you can easily give a series Land Rover, and they aren't all that cheap or plentiful, compared to the alternatives. Few years back, when there were fewer diesels around, they made more sense; but now, it seems a very different story.
So, realistically, it will cost between five hundred to a thousand pounds to get a 'converted' engine into your engine bay, to any decent standard, more to do it well.
How much life and reliability are you prepared to sacrifice for any extra performance and economy, depends on how highly you rate each facet; you'll have to make a compromise that best suits your aspirations and your budget.
A 90 or 110 is a pretty good alternative to a conversion, and certainly will prove more practical and liveable than all but the best done conversions. Keeping the Series Standard, is certainly the cheapest thing to do.
At the budget end of the conversion spectrum, you CAN get some gains with the cheaper 2.5NAD or Prima Conversion, and retain reasonable reliability and engine life.
Top of end of the conversion spectrum, doing a lot of reconditioning of the bits you use, you can do a conversion as part of a full or rolling restoration, that will give you a Land Rover with useful performance and or economy, almost or equal to what you'd get with a 90/110, but with a lot more life and reliability built in. Economically, you could build yourself something cheaper than you could buy a 90/110 with as much life in it..... but that is very different to it being cheaper than you could buy a 'serviceable' 90/110 for! It still wouldn't be 'cheap'.
In between, there are plenty of alternatives; few of which will deliver brilliant value for money; many of which can be horrendously expensive for what you end up with, or be peculiarly unreliable or difficult to live with.
But any way, other alternatives. If you look at Engines - At a Glance, I have compiled a Table of what I know about each of the engines I have found out about. It is no way a comprehensive or exhaustive list, and I cant guarantee that it is entirely accurate, but it is a starting point for your own re-search.
And, I have to go back to a comment in 'You can do ANYTHING to a Landy!', take a step back and have a good hard think about the 'problems' you want to solve with your conversion.
But, a whole scale engine conversion isn't the only way you could go. If you want more performance, you could tune a standard two and a quarter petrol. If you want more economy, you could fit an LPG kit to a two and a quarter petrol. Or if you want more reliability, you could undertake a rebuild, or buy a remanufactured engine. Or, in fact any combination of the three.
And at the end of the day, I can't say what is the best choice of engine or conversion, or argue one way or the other in favour of keeping the stock engine. All I can do is point you in the direction of making an informed decision of your own.
Some Further Reading / References
Other related stuff on this site:-
You can do ANYTHING to a Landy!
Customising; modifying; & building a better mouse trap. Worth giving some thought to your ideas before picking up the spanners.
Taking on a Project
Get Organised & Don't bite off more than you can chew! Some practical techniques of project management. Food for thought before you get TOO enthusiastic with the spanners and angle grinder!
My opinion & findings on the variouse ways you can do a V8 conversion to a Series, from the 'period' V8 on series box, through to full on Range-Rover based hybrid, compared to a tweeked four-pot.
Dropping in a V8
Magazine Clipping Article: The 'Period' conversion: V8-ing By Robert Ivings. Taken from a mid eighties magazine clipping I was sent. A useful example of what's involved in fitting a V8 into a Series with series transmission.
V8 into Light-weight
Magazine Clipping Article: The 'Period' conversion, using carburetted V8 on Series 3 gearbox: this time V8-ing by John Craddock, and fitted to an ex-military air portable or 'Light Weight' Land Rover
Fitting a Ford V6
Magazine Clipping Article: Chris Perfect fits a 3.0l carburated 'Essex' engine to his trialer, with a Steve Parker adapter kit
Fitting a Prima'
Magazine Clipping Article: An 86" Series I gets prima'd with a Montego turbo diesel engine.
TDing a Series II
Stuart Crane's photo-blogg of a Td installation in his Series II
Engines at a Glance
Data & Info I've found on what I've found out about!
Prima Conversion Specialistt
Prima Conversion Specialis
Prima Conversion Forum
Place to enquire or discuss Prima Converted Land Rovers
Conversion & Precision
Engine Fitting Kits for Daihatsu; Ford; Rover V8; Nissan; & Isuzu, t o Series Gearbox; other engines to other rover 'boxes.