[SGVLUG] [OT] Especially for Tom & his Prius.... [my rebuttal, then I'll shut up]

[David Lawyer]

On Wed, Jul 19, 2006 at 02:19:00AM -0700, David Lawyer wrote:
>  The peak efficiency of diesel should be higher due to both
> it's higher compression ratio and faster burning.  But per tests in
> 1949, a gasoline engine (installed in an Oldsmobile with water pump,
> fan, generator, etc.) was nearly 30% efficient (at best with a 12:1
> compression ratio).  See SAE Journal, June 1949, pp.17-21 "High
> compression engine performance" by Max M. Roensch.  But at a 10:1
> compression ration it was only about 27%.  At 8:1 compression it was
> only about 25%.  

[snip]
> 
> Another troubling thing is the high efficiency reported in 1949
> for an engine that must have had only 2 valves per cylinder and likely
> wasn't valve-in-head.  Was it really this good?

It was valve-in-head.  I just looked on the Internet and it's claimed
that the 1949 Oldsmobile V-8 was indeed the very first mainstream V-8
to have overhead valves (valve-in-head).  So I now have more
confidence in the 1949 tests.  We haven't improved on engine
efficiency all that much since then (over a half century ago).