LPG versus Petrol. What's your view

[johnydep]

it's probably been done before, but it seems to be a passionate subject to most of us. So I created this thread to stop poluting another thread http://www.fordforums.com.au/showthr...7&page=2&pp=25

I have used LPG, I have a fitters licence and have had something to do with it for the past 15 years.
My feelings are mixed though, from what I have seen a well maintained LPG engine for the average user will last as long as a petrol engine, but most don't get the correct servicing & end up with oil leaks, mechanical noise & excess emissions.

A correctly maintained LPG engine should have the same or better life span than its petrol counterpart, but that's rarely the case & the manufacturers know it.

The reasons;
LPG produces more acids than petrol, the oil breaks down quicker but looks clean, the acids attack bearings & seals. Check out the recomendations from the manufacturers, you'll see that LPG engines require a higher rating.
LPG also causes oil to thicken with age, so not changing oil & filter at specified intervals leaves a too thick oil to circulate to the valve train.
Petrol has a natural cooling effect, this causes the air/fuel charge to be denser (more power) and also helps cool the valve & top piston ring. LPG does not have this, so there is more heat stress in the combustion chamber.

So there is good and bad with LPG.

http://www.wps.com/LPG/WVU-review.html

Performance and drivebility of propane vehicles is essentially the same as for gasoline vehicles. For propane, the gas displacement effect is 4%, it means that the displacement of air by propane causes reduction in power of 4 % (volumetric efficiency decrease) from an equilevent gasoline counterpart. Gasoline on the other hand, provides evaporotive cooling of the intake air which increases the intake air density and increases the power. Test results show 6 % less power with propane than with gasoline[11]. Propane has a research octane rating of 110 to 120, thus, it resists engine knock better than gasoline (gasoline 87-94 ) allowing a higher compression ratio for the engine, see Figure 1. Propane contains about 5 % more energy per unit mass however the density is nearly 32 % less. The net result is that a litre propane contains 28 % less energy than a litre of gasoline, Table 4. Assuming that an engine is operated on propane and gasoline with equal efficiency, more litres of propane will be consumed to provide equilevent performance. Fortunately, engines generally operate on propane with greater efficiency than on gasoline so that the increase in fuel volume is not as great as the energy comparison suggests. Propane fueled vehicles can achieve the same driving range as a gasoline vehicle by installing a slightly larger tank. Propane use consumes approximately 5 % more fuel for equivelent performance but it costs 15 % less than gasoline.

Question; Two identical engines, one with slightly less power, which one will wear out first if driven in identical ways?