Multipoint Sequential Gas Injection Systems (SGIS) are the most appropriate type
of LPG conversion for vehicles built after 1999. Earlier vehicles with a plastic
inlet manifold should also have this type of conversion. Kit costs have reduced and
set-up of the systems is now considerably easier.
The sequential system injects LPG as a vapour for each cylinder, very close to the inlet valves. The gas ECU works with the petrol ECU so that, when switched to gas, the engine is run as it was designed to be run (except for the change of fuel).
The system offers slightly improved economy and performance (when compared with
induction systems) and eliminates the possibility of
spit-back. Click here for more details of kit components.
The Epoka Gas Injection System is designed for engines with carburettors or throttle-body or mechanical injectors.
The system injects LPG as a vapour for each cylinder, very close to the inlet valves. This eliminates any power loss caused by mixer venturi constriction and also eliminates the possibility of spit-back. The gas ECU does not require any petrol injector pulses, but calculates gas injector timings from manifold absolute pressure (MAP), RPM. and a tuning map.
This type of system is the simplest type of LPG conversion carried out. Suitable for all types of
vehicle built before 1999 (except those with a plastic inlet manifold), the system introduces gas to the engine in vapour form through the inlet manifold. When switched to gas, the way the engine runs is controlled by the LPG system.
Open-Loop Induction Systems Older, carburettor vehicles and early, injection models that do not have a catalytic convertor can be converted to an open-loop system where the LPG reducer and power valve are used to control the inlet of fuel into the engine. This is the simplest and cheapest solution. However, with the addition of a lambda probe in the exhaust, the system can be upgraded to closed-loop operation, with all of the benefits described below.
Closed-Loop Induction Systems Later petrol-injected vehicles have catalytic converters and require LPG systems that use a slightly more sophisticated management system that reads the oxygen sensor in the exhaust. This then controls fuelling using a stepper motor, to give the most efficient fuelling at all times, resulting in better fuel economy and better throttle response. Click here for more details of kit components.
Diesel LPG Conversions
Diesel engines can be converted to run partly on LPG, partly on diesel. This method uses the combustion of the diesel to ignite the LPG. The benefits include large increases in power and reduction in emissions, particularly the black smoke often associated with diesels.
Typically a ratio of 30% LPG to 70% diesel is possible. No adjustments are required to the diesel injection system and fuel savings come from the fact that throttle openings are lower due to the greatly increased power, which basically means you do not have to press the accelerator as hard to get the same performance.
Fuel savings up to 30% are possible with the increased power levels seen as a major benefit to users.