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DIY LPG

Chris Perfect fits a DIY LPG Kit to a V8 Range Rover

The vacuum-operated Ecomax mixture control allows you to adjust the system if you need to (fuelConsidering a Liquid Petroleum Gas (LPG) conversion? Want to do the job yourself? Chris Perfect explains what's involved, and converts an EFi Range Rover

The increasing availability of LPG as a relatively cheap and environmentally sound fuel means that thirsty, large-engined Land Rovers can be run at the cost of a smaller petrol car, and with lower emissions.

This has resulted in an increasing number of firms offering to supply or install various systems, all of which they claim, rightly or wrongly, are safe.

The best LPG conversion companies will understand not just the LPG system requirements, equipment and regulations, but also the needs of your particular vehicle and its engine.

A bespoke system designed, manufactured and installed correctly should give many years of good, safe performance.

Many practical Land Rover owners want to do every job themselves, not only to save money, but to ensure the vehicle is exactly how they want it to be.

They are the competent DIY owners who will be painstaking and careful in any job they do, whether sorting out the brakes or steering, or fitting an LPG system.

They also want to gain the knowledge that will enable them to carry out their own regular safety checks and maintenance on the system.

As a result, DIY LPG systems that are specifically developed for Land Rover engines and backed up by full instructions and help, have filled a real need.

Safe systems

Safety and performance are paramount when considering an LPG installation. But let's put things in proportion.

Petrol is a familiar, though very hazardous fuel. A cupful has the explosive potential of a small bomb. A petrol tank containing liquid and vapourised petrol, connected by soft tubing to a hot engine needs treating with respect, especially when you consider that the petrol tank is plastic or thin, sheet metal.

An LPG fuel tank that has been designed and built to appropriate codes is of relatively heavy steel construction, 3-4mm thick, and will have been pressure-tested by the maker.

The LPG pressure is about 100-150psi (8-10bar). The tank should have a pressure relief valve installed and the tank's connection to the system should always be closed unless opened by a solenoid valve.

The fuel feed to the engine will be through plastic-covered copper piping secured with metal P-clips at the correct spacing, and with anti-vibration provision where you need it.

Under the bonnet, electrical solenoid valves that are held open only when the engine is running allow LPG to flow from the tank to the engine. The moment the engine stops, the valves isolate the system and the gas shuts off.

So, in many ways, LPG systems may be safer than petrol. Despite this designed-in system safety and its fail-safe characteristics, it is essential that components are installed correctly —and that means following the installation instructions to the letter.

Safety concerns

Last year, Trading Standards reported a high percentage of defects in a sample of LPG-converted vehicles. These included professional installations and various system types, so you should research it all carefully before going for a particular installation. Learn enough to be able to form a reasonable judgement, and also to be able to monitor and maintain the LPG system whenever you need to.

Older equipment and systems

Some existing LPG installations are now quite old. System components stamped to the earlier code of 67/00 and installed before August 2001 are still acceptable, but 67/00 (or uncoded) parts should not be used in systems installed after that date. New systems should use components with the current 67/01 code. Apart from possibly affecting system safety, the use of non-coded components may invalidate your insurance cover.

LPG components are now turning up at autojumbles and that's where you should avoid them: out of date, untested and secondhand parts are potentially dangerous. I have seen old tanks being offered for sale with unsatisfactory manual valving - or even with no valves at all.

Reliable performance

LPG systems vary enormously and, whether they are for EFi or carburetted engines, there are big differences in power output, economy, reliability and convenience.

It's not a good idea to choose only on price. Although a very basic system may actually run the engine, it can cause serious problems if important factors are ignored. Inadequate components can lead to lean running, causing poor power and economy. They can also produce excessive cylinder temperatures and burnt pistons, and cause damage to components through backfire.

EFi systems can be badly affected if you take a shortcut to bypassing the petrol system, when switching the fuel to LPG. SU and Stromberg carburettors can deteriorate if the needles are not lifted when running on gas. Mixtures under light load are frequently too rich unless there is a means of controlling the mixture under both full- and light-load conditions.

If you intend buying an LPG kit, make sure that your supplier is familiar with your type of Land Rover and will provide evidence of performance, such as dynamometer tests results, plus any back-up service that you may need in order to look after the system in the future. Remember, the average garage will not know what to do with the system!

What's involved?

The picture sequence shows an Iwema LPG kit installed on a 1988 3.5-litre EFi Range Rover. This installation illustrates some of the points we've mentioned. For example: the 3.5 EFi engine (without catalytic converter) has the earlier flap-type air meter which is vulnerable to damage and also affects the air-flow when running on gas - that problem was solved by fitting a special L-jet opener.

How hard? How easy? 

How hard? - 2-spanner rating

Time? - Two days, plus some planning time.

Installation of an LPG conversion is not a difficult job in itself. However, LRO recommends that you should have a good level of competence and understanding, to install the systems safely and reliably. Follow the installation instructions implicitly and, if in any doubt, have your work checked over by the supplier, or a competent specialist. Special tools needed? Electric drill and bits; Screwdrivers and spanners; Crimping tool for electrical connections.

The strong, 100-litre, pressure-tested tank is secured to its base frame by four plastic-coated steel straps (two straps for tanks under 100 litres). The floor coverings must be removed so that bolts can be fixed firmly through the floor panelWith the strap bolts installed, the top edge of the frame is then fitted with a plastic strip that will protect the LPG tank's seating surface

 The tank's filler hose (right) passes out of the bodyshell through tight grommets. The valves on the tank are housed in a sealed box so that any leakage can be directed through the corrugated vent hose (left) which leads to a safe discharge point beneath the vehicle, away from the exhaust The tandem vapouriser (left) feeds gas from the tank through the vacuum-controlled Ecomax flow adjuster (orange). This corrects the mixture in light-load conditions. LPG arriving at the vapouriser passes through a filter and solenoid valve. The vapouriser allows the LPG to expand to a gas

 This is the emulator for one bank of injectors. As the engine switches from petrol to LPG it interrupts the signal from the ECU and halts the petrol injection, controlling the moment when petrol ceases. This ensures the smooth running as the auto switch changes over and the LPG comes through. This is vital to prevent momentary fuel starvation, which will cause backfire The plenum chamber is then released and held out of the way to reach the injector plugs that are situated on the other side of the engine

Each injector connection is unplugged and then reconnected to the electrical sockets that are provided on the wiring loom from the emulator The facia-mounted control console displays the tank contents and enables easy changeover between fuels - automatically, or manually at the flick of a switch. It also lets you adjust the engine speed at which the usual change from petrol to LPG takes place (the engine always starts up on petrol)

This is the mixer that feeds LPG into the incoming air stream and ensures good fuel/air mixing by the action of the tapered venturi Larger capacity engines, such as the 4.2-litre V8, would use this 50mm diameter mixer with two inlets. This ensures air flow isn't restricted, and provides high flow when needed for full power. The Y-shaped adjuster sets peak flow

By putting the crankcase breather upstream of where the gas is introduced there is less danger of LPG getting into the sump. This could otherwise have very dramatic consequences! This is the Iwema L-jet opener with a switch that connects it to vacuum when the engine switches to LPG and opens the air meter flap. This

With the help of a hand-held tachometer, the maximum-flow adjuster is set to an engine speed of 3000rpm, to ensure optimum fuel feed On this 4.2-litre Range Rover LSE, the large 50mm mixer has two feeds and a Y-type adjuster to provide adequate and safe fuelling

WHAT TO ASK

• Does the supplier have proven experience, and a good track record for regularly supplying systems for your model of Land Rover?
• Can the supplier demonstrate the performance and reliability of the system?
• Is performance data available?
• Does the supplier offer a good aftersales, technical back-up and advice service?
• Are the components of the kit designed, manufactured and tested to the appropriate standards and marked R67-01 ?
• Are comprehensive English language instructions provided for fitting, setting, and commissioning the system?
• Are all components new? Avoid secondhand.
• Is a tuning and inspection service offered?
• Will you need any extra components?
• Does the system cater specifically for your type of carburettor or injection system?
• Is the system appropriate for the power output of your engine?
• What do other users think? Talk to them directly or via the internet

 

LPG Manual

Dutch LPG conversion Spcialists  IWMA Enterprise publishes a manual covering installation, use and problem solving for LPG systems. LPG Duel Fuel for Automotive Engines is co-written by LRO's specialist, Hugo van Osch, and Gordon Finlay. Copies are available at £32.45 including postage by contacting Gordon Finlay on 07974 397227. -mail g.finlay@rdplus.net

 

Comment (By Teflon)

It's not a definitive 'How To', and I would SERIOUSLY not recommend that any-one attempt an LPG conversion armed with nothing more than this, and a bunch of bits procured of e-bay! Essence of the article is:

'get a kit - follow the instructions'

Which you have to take with a pinch of salt, baring in mind that the author sells LPG kits! However.... he is a recognised Land-Rover 'Authority', and his business is an off-shoot of his interest, rather than the other way around.

And to be honest, the advice is fairly 'sound', and the article does give a reasonable insight into the bits of an LPG system and what's involved in fitting one. Obviously it's no ten minute job, but its not too daunting or demanding either

 

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