As LPG has only 80% of the calorific value of petrol, then you would have an engine 80% down on power for the same fuel consumption.
Remember fuel consumption is actually slightly worse on LPG, but the fact that it's much cheaper to buy means people quote an equivalent fuel consumption figure. But when has cost bothered a race team?
Buck
You're partly right, Buck. The calorific value of LPG is less than that for petrol, but against that, as LPG is a gas (rather than a vapour as with petrol) you get a much more complete 'burn' of the fuel in the cylinder (which is also why LPG is much 'cleaner'). Ok, the net result is that LPG is still down against petrol, but not by that figure. Depending on the engine, the LPG equipment etc, it can be as little as 5%.
This is for 'road' cars - I have no experience or data relating to 'tuned' engines.
Del
But with a turbo thrown into the mix, it gets more interesting.
Under high boost, there is a much lower risk of detonation if you're running on LPG, so you can basically whack the boost up to whatever the drivetrain will take.
And if you bung LPG into a clattery diesel engine you get heaps more grunt and better fuel economy (Don't try to run it exclusively on LPG though, otherwise you may melt your engine) (OK, you WILL melt your engine)
An engine runing on North Sea Gas will have much cleaner oil, and won't need a cat, but you must bear in mind the onerous responsibility of dragging the pipe around behind the car.
I once set off a fire alarm with a particularly noxious bottycough. My wife says I shouldn't be proud of that, but I can't help it.
