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Old 01-25-2012, 01:39 AM   #88 (permalink)
Ken Fry
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Quote:
Originally Posted by drmiller100 View Post
back to an earlier question, but lets put some real numbers to it. Lets say our car needs say 22 horsepower at the wheels to go 70.

Are we better off with a 500cc engine turning 4000 rpm, or a 1500cc engine running 1300 rpm?
You can use the same Saturn chart. The Saturn shown produces about 120 bhp at 5500. So a 1500cc engine like it would produce 90 HP, and 500 cc engine would produce 30 (which match the calculator numbers for 5500 rpm). The chart torques would be multiplied by 120/90 for the 1500, and 120/30 for the 500.

I think you'll find the two engines very close in BSFC at that HP.
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