Autogas systems LPG, LPI and LPDIDie Conversion of motor vehicles to run on autogas (LPG) will become more popular the higher the gasoline prices rise.
Unfortunately, not every customer is satisfied with the performance of their conversion company. If the installation is not done according to the installation instructions of the gas system manufacturer and the rules of the ECE 67 or ECE 115 carried out, it can lead to unsatisfactory driving characteristics or even Engine damage come. If the conversion company cannot remedy these deficiencies after several attempts, the customer will be legal or even legal help make use of.
Here we can help: We provide you with an expert opinion on your gas system that can be used in court. We check if the installation was done according to the gas system manufacturer's instructions and the legal requirements. We continue to check, in particular, whether the gas system has been adjusted and tuned to your vehicle. For this purpose, we use modern PC and EDP software. We can currently verify 38 of the known LPG manufacturers.
We perform GAP and GSP, these are official tests. The scope of these checks is a component of our expert opinion.
General information about LPG versus gasoline during combustion in a gasoline engine
Gasoline-powered motor vehicles are converted to run on LPG (Liquefied Petrol Gas) because the costs for LPG is about half of gasoline, per unit of volume. The conversion companies advertise with the promise that fuel costs will be halved by converting to gas operation.
The main components of LPG are propane (C3H8) and butane (C4H10). From an environmental point of view, the combustion of LPG generates less (approx. 10%) CO2 than the combustion of gasoline, which consists mainly of octane (C8H18), because the hydrogen content in LPG is higher than in gasoline. Hydrogen burns to harmless water (H2O).
The price advantage of LPG is somewhat reduced, since LPG (24.9 MJ/l) has a somewhat lower calorific value (energy content per unit volume) than premium gasoline (32 MJ/l). The consumption therefore increases slightly, but does not correspond exactly to the difference in calorific value, since LPG is burned more effectively in the gasoline engine than gasoline.
The more effective combustion of LPG results mainly from the higher anti-knock properties of LPG to gasoline. Knock resistance is the term used to describe the unwillingness of the fuel to ignite. In the conventional gasoline engine, the gasoline/air mixture is first compressed. Then ignited at the right time by a spark plug. The ignitability of the gasoline/air mixture should be as low as possible, so that it does not ignite itself uncontrollably as a result of the heat of compression; this then leads to the so-called engine ringing or knocking. The unwillingness of a fuel to ignite is measured in octane. Regular gasoline has at least 91 octane. Super gasoline has at least 95 octane. LPG has an octane number of approx. 120. Because LPG is more reluctant to ignite, the ignition system has to work harder. Spark plugs and ignition coils are subject to wear during operation. When running the gasoline engine on LPG, these components need to be replaced more frequently than in gasoline mode.
In the gasoline engine the gasoline with air in a mass ratio mixed by 1:14.7, which is then referred to as λ=1, a stoichiometric ratio. With this mixture, the fuel can be completely burned to water and CO2. Emission of pollutants is lowest. If too little fuel is available for combustion (λ>1), harmful nitrogen oxides are produced during combustion. If too much fuel is fed into the combustion chamber (λ
During the combustion of a stoichiometric gasoline-air mixture, temperatures in the combustion chamber are about 2.000 °C. If this mixture is leaned out – there is less gasoline than could be burned with the amount of air (λ>1) – these temperatures rise significantly and component damage can occur, especially to the valves. During combustion of a stoichiometric LGP/air mixture, combustion temperatures increase only by approx. 80°C compared with gasoline combustion, which has only a very slight effect on component service life. For the lubrication of the valves with respect to the valve seats. Additives are added to the gasoline to clean the engine. These additives are missing in the LPG, as a result the valves are not lubricated and increased wear may occur. Furthermore, deposits can form in the engine – especially in the cylinder head and on the valves – which do not allow the valves to close properly and can lead to unwanted glow ignitions.
The Main components of an LPG system The main components of LPG are the gas tank, the vaporizer, the injection nozzles and the electronic control unit. From the gas tank the still liquid gas reaches the evaporator. The heat required for vaporization is extracted from the engine's cooling system. The now gaseous gas reaches the injection nozzles via a distributor, the rail. On the rail, there is an injection valve for each cylinder, which is opened electrically by the electronic control unit in order to supply the calculated amount of gas to the cylinders for each individual combustion process. The electronic control unit processes the injection pulses from the gasoline control unit. Calculates from this the opening times of the injection nozzles. The almost universal electronic control unit of the gas system must be adjusted and calibrated for each vehicle for almost all driving conditions – not only in idling mode – in order to ensure optimum engine running in gas mode. Furthermore, installation errors such as z.B. Installation position of the evaporator, hose lengths, nozzle selection, installation position of the injectors, etc.