Re: Gasoline grade BTUs per gallon?



"K. Jones" wrote:

Bill, would it be more accurate to say an engines can "*be built* with
slightly greater efficiency by utilizing a higher effective compression
ratio"?

That's a diesel ! They have much higher compression ratios than gasoline engines
and are therefore more efficent.

Saab's new bio-power gasoline engines that run on E85 are more efficient on
ethanol by turbocharging at a higher boost pressure than on gas that utilises
the higher octane of ethanol ( a bit similar to having a higher compression
ratio too ).

AFAIK, on a typical, un-modified, car engine, as delivered by the factory,
built to use say, 87 octane gasoline, you will see no "preformance
improvement" by using "premium" (say 91 octane).....more likely less
performance.

Less performance ? Why do you say that. It flies in the face of experience.

It's only on engines that have a higher effective compression
ratio, that performance gains will be found.

Higher compression ratio engines can make better use of it.

If my engine is designed for "regular" gasoline, I'll get slightly more
miles/gallon, and a higher "max power" from regular gasoline, than I will
from premium.

Probably not. It depends hugely on the ECU programming. though.

Graham

.