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Old June 13th, 2011, 12:37 PM   #56
greg737
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Join Date: May 2009

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Quote:
Originally Posted by CThunder-blue View Post
Not sure what you mean?
He's saying that 14.7:1 (14.7 to 1 air to fuel ratio) isn't what you always want in a gasoline engine.

For maximum horsepower (in a gasoline powered engine) you tune to achieve a 12.1:1 to 13.1:1 air to fuel ratio.

For maximum fuel efficiency (in a gasoline powered engine) you tune to achieve about a 16.0:1 air to fuel ratio.


Here it is again, copied from a website devoted to fuel injection tuning:

To make maximum power, we want more fuel than stoich. (richer, aka. lower AFR), because we want to be sure to consume ALL the oxygen (even if a little fuel is unburned). Typical full power AFR are 12:1 to 13:1 for gasoline. This is because it is the air flow that limits power (not fuel flow),
To get maximum fuel efficiency, we want to make the mixture a little leaner (higher AFR, about 15:1 to 16:1) than stoich to be sure of burning all the fuel,
To get minimum emissions, we want to run stoich. (14.7:1) as much as possible.
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