Engine efficiency listings question

[JohnEd]

Recently someone was comparing two engines and concluded that the MPG from each would be very close.  They listed numbers like .317 gallons per hour per horsepower.  That is a priceless way to compare the efficiency of engines and models of engines and year to year stats for the same engine/model.  Where can I find this  in a table that lists all engines.  Does that exist?  I googled it but didn't get what I wanted.

thanks,

John 

[pvcces]

John, that is a lot more likely to be .317 pounds, not gallons, of fuel per horsepower hour. This gives you about 23 1/2 horsepower hours per gallon of fuel.

The best figures that I can recall for DD two strokes was about .44. The sheet said that this did not include accessories. At the time, I remember thinking that this meant that you had to deduct for the blower because it was viewed as an accessory.

Mileage will depend on light loaded fuel economy, but none of the performance sheets that I have seen cover this subject.

For what it's worth.

Tom Caffrey

[TomC]

Most all engine manufacturers do not list their fuel efficiency burn anymore-that's why you can't find it.  The engine manufacturers ran into too many problems with claims of bad fuel mileage (when in actuality, it is the loose nut behind the steering wheel that has the most affect on fuel mileage).
From what I remember, mechanical non turbocharged 2 strokes got in the .41-.44 range, mechanically injected and turbocharged 2 strokers got in the .36-.38 range, electronically controlled 2 strokers and mechanically injected 4 strokers got in the .34-.37 range, and electronically controlled 4 strokers down in the .31-.34 range.
The rule of thumb- starting with a none turbocharged 2 stroke-turbocharge the 2 stroke and it is good for about 1 more mpg.  From a non turbocharged 2 stroke to a electronic 2 stroke or mechanical 4 stroke-good for about 2 more mpg.  Go from a none turbocharged 2 stroke to a electronically controlled 4 stroke- good for 3-5mpg more.  Good Luck, TomC

[JohnEd]

Well, I didn't even get a single point for asking the right question

Thanks Tom P.  It was pounds just as you said.  I thought I could compare "theoretical" efficiency/MPG with that data.  The load and driver and other stuff must fudge the numbers all over the place in reality.

TomC

Good explanation on why I am having so much trouble digging up data on the subject.  So, it's a conspiracy.

You cut right to the chase and gave me what I was looking for without my actually knowing beforehand.  The MPG of each variety and each generation is exactly where I would have gone.  Thanks.

John