I don't know where you got you figures from, but here is a dealer trying to
selling a 125 hp Yanmar diesel against a 220 hp gas engine who "claims" the
Yanmar uses 6.3 gallons per hour, or a little less than 20 hp per gallon per
hour.

http://www.mastry.com/article_1.htm

* dealer also "claims" the 220 gas engine (less than 2x the size) burns about
3x the fuel, something the EPA doesn't agree with)



OK, the Flywheel Horsepower of the Yanmar 3YM30 is 29HP at 2800 RPM, while
burning less than a gallon an hour of diesel. That's what the engine
manufacturer says in their spec sheet.

Fuel economy at WOT will be closer to the "1 gal/16hp" rate, or if you
measure
propeller output you'll be closer to that number. However, when one talks
about
"pushing a Benny with a 20hp engine" they really mean running a 2GM20 at 2600
rpm, where its putting out under 8 hp at the prop and burning less than half
a
gallon an hour. I have 2 2GM20's that consistently use 0.4 gallons each per
hour.

And besides, the gallons in Britain are 25% bigger.




"JAXAshby" wrote in message
...
dougies, you idgit. That is NOT the manufacturer's spec sheet, but rather
some
clown's ramblings. This time go check the spec sheets that engine
manufacturers put out.

A good explanation is at

http://www.prime-mover.org/Engines/GArticles/bsfc.html

which BTW also quotes some figures for various types of engines... which
BTW don't agree with your figures, surprise surprise.

Fresh Breezes- Doug King