Robert Bates wrote:
I was reading on a site about someone running a Chevy LS1 that was
derated
to 320hp and bone stock that was running 10.9 gal/hr at cruise. Does
anyone
have experience with these engines? If it is accurate, that is quite
a
savings over Lycoming and Continentals of that HP.

Hi, Robert!
Typically, the SFC of 4-stroke IC engines, liquid or air-cooled, is
0.5lb/hp-hr at best power mixture of about 12.5:1 A-F. Leaned for max
economy this will range from O.45 to 0.38 depending upon the engine.
Those that have 0.38 are very efficient. Some new Continentals or
Lycomings are getting this value leaned for best economy. The 10.9
gal/hr says that this engine, if it's leaned for best economy, is
producing between 148hp and 168hp, or about 50% power. "Cruise" is an
ambiguous designator, and doesn't really convey any information about
the engine's operating parameters! Be careful of these kind of claims!
So to get a good estimate of an engine's full-throttle, max. power
output, divide the fuel flow in gallons/hour by 0.5 then multiply this
by the weight of the fuel, which for av-gas averages about 5.85lb/gal.
Paul