The LPG immediately vapourises after being injected. This vapourisation process rapidly cools the surrounding air. This cooling effect increases the density of the air-fuel mixture, ensuring power and torque are maintained and fewer CO 2 emissions. Conventional LPG conversion gas conversion put the LPG through a device called a vapouriser before introducing it into the intake manifold.
An old style LPG conversion vapour system can actually restrict vehicle performance, in comparison to liquid LPG conversion. You get a substantial fuel savings with an LPDI LPG conversion, combined with equal or better engine performance, great drive-ability and lower tailpipe emissions. A vehicle with a state-of-the-art liquid LPG conversion gas conversion produces at least the same amount of power when running on LPG, as compared with running on petrol.
Direct injection LPG conversion are so reliable that more than 1 million liquid LPG conversion gas conversion have been factory fitted by automobile manufacturers around the world.
The manufacturers of these systems are so confident that they offer extended warranties on the liquid LPG systems. One of the biggest advantages of LPG conversion vehicles is the savings realised on fuel costs. With exceptions, it is possible to fit most types of LPG system on most vehicles, and indeed the vehicle would then run on LPG, but there can be serious problems in fitting the incorrect type of system on a particular vehicle. Each type of LPG fuel system is designed primarily to work with one type of petrol fuel system.
This page explains the different types of LPG fuel systems and which type of petrol fuel system each is usually fitted to. There are several main types of LPG fuel systems and many different manufacturers producing systems of each type.
Open loop means the fuel system gives the engine a fixed amount of fuel for any particular operating condition. Carburettors and early fuel injection systems work in this manner all the time. By keeping the mixture correct performance, economy and emissions are all optimised.
Multipoint systems have a separate point for each engine cylinder just like with multipoint petrol injection systems. Referring only to some types of multipoint LPG system, sequential means each LPG injector injects fuel in the same sequence as the engine cylinders fire, in a sequence one after the other.
Below is a description of each of the main basic types of LPG fuel system in the order in which they were developed. The further down the list, the more advanced and suitable for modern vehicles. Single point or mixer open loop systems. Suitable for carburettor and some early fuel injection engines. Single point or mixer closed loop type systems. Suitable for most fuel injected vehicles produced up to around year and a smaller proportion of more recent vehicles.
These systems can also be fitted to carburettor vehicles if a further inexpensive part Lambda probe is fitted in the exhaust. These systems use most of the same parts as the single point open loop systems described above, but have a few additional and different parts.
The manual control valve is replaced with an electronically controlled LPG control valve which is controlled by an electronic unit that has a computer. In addition, when you put your foot down on the accelerator they can be set up to give a richer mixture for more power - this is what carburettors try to do and fuel injection does. They are completely independent of the petrol fuel system, so as long as the ignition system on the car works the engine will run even if the petrol fuel injection system is completely broken.
They have some of the same disadvantages as the single point open loop system above, in that a backfire is possible because the whole inlet manifold will contain a combustible mixture again as with carburettors. This system is suitable for many fuel injected vehicles, usually those produced up to around the year but in some cases later vehicles too.
When compared to fully sequential LPG systems described below, they cannot control the mixture as quickly or accurately but on suitable vehicles this makes very little difference in real terms. On most petrol injected vehicles most petrol injection systems are closed loop , the advantage described above about these systems being independent of the petrol fuel system can also be a disadvantage. This is because the petrol system will always be running in the background, thinking it is controlling the engine fuelling when actually of course the LPG system is.
What this means is that when you then switch back to petrol the vehicle can be hesitant until the petrol system retunes itself.
Most later vehicles will see that the petrol adjustments have gone to the limits, will illuminate the engine warning light and may go into an error mode. This reason, and the potential for backfiring, is why these systems are only suitable for certain models of fuel injected vehicle, usually older vehicles and those without plastic inlet manifolds.
Multipoint non sequential systems. Most of these systems can also be fitted to carburettor vehicles if a further inexpensive part Lambda probe is fitted in the exhaust. There are actually a few different subtypes of these systems but they work in mostly the same way. However, you may visit "Cookie Settings" to provide a controlled consent. Cookie Settings Accept All. Manage consent. Close Privacy Overview This website uses cookies to improve your experience while you navigate through the website.
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