[RustyLugNut]

Originally Posted by Jack-Lee

Hi,
maximal effciency of 36% cannot be possible.
The "VTEC" Engine from Honda reach 215g/kWh at the best point!
File:Honda Insight 5mt.jpg - EcoModder

Heat engine - Wikipedia, the free encyclopedia
Burning temperatures about 2500°C and exhaust temperatures about 1000°C equals a maximal efficency of 54%.
Theoretical efficency for gasoline engine -> 63%
http://einrichtungen.ph.tum.de/T37/S...SS07/page3.pdf

Gasoline has a power density potential of 0.0122225 kW*h/g. Multiplying that power per gram potential by BSFC:

(0.0122225 kW*h/g)(215 g/ kW*h)=2.62784

Dividing into unity:

1/2.62784=0.381 or 38.1% thermal efficiency.

This is achieved via lean-burn combustion in the Honda Insight. Someone who is intimate with the engine will know more about this. Please make corrections as needed.

The 225 g/kW*h BSFC that has been published for the older Toyota Prius engines would yield:

1/(0.0122225 kW*h/g)(225 g/kW*h)=0.364 or 36.4% thermal efficiency.

This is achieved with over-expansion (Atkinson) cycles.

Both engines were state of the art at the time and were leaps and bounds better ( in thermal efficiency ) than gasoline engines of the time.

Modern engines hope to do better and are closing the gap between gasoline and diesel engines in the measure of thermal efficiency.

Green Car Congress: Toyota targeting thermal efficiency of more than 45% for next-generation gasoline engines for hybrids