I think I remember that an internal combustion engine is about 23% efficient
(work out/energy in), nearly the same as the human body.

James
Mark Dorm wrote:

> The heat (that isn't converted to motion) is still lost energy - its a lack
> of efficiency - its energy released from the fuel that moves out into the
> environment - I forget but isn't a gas engine only about 40 or 60 percent
> efficient in its transfer of energy from fuel to motion - wouldn't we better
> off measuring the speed of the piston upon explosion - and if theres an
> upper limit for how fast a particular piston can move then won't a hotter
> spark (that goes beyond that limit) just result in more heat being lost to
> the system