Here is my dyno of mods with air/fuel ratio.

Keep in mind that the dyno may be suspect so the numbers above 5100rpm and peak hp numbers are probably incorrect.

The only other dyno with air/fuel ratio I've seen was in the Stillen instructions Russ posted on his site. Has anyone else done one? Mine seems kinda rich.

http://web.tampabay.rr.com/maxgator/airfuel.BMP

Stillen's:

http://www.5thgenmaximas.com/howto/scinstall/dyno4.jpg

 

It looks rich below 2750(supposed to be, I think), perfect till 4000, but you start to lean till redline.

I bet you would see a gain in power from 4000-REDLINE with a fuel-pressure regulator.

 

Actually, I think it is lean early and rich later. Here's my attempt to explain; I usually get it confused.

The bigger the number for the air-fuel mixture, the more air and the less fuel = the "leaner" mixture.

The smaller the number for the air-fuel mixture, the less air and the more fuel = the "richer" the mixture.

Think about "rich" and "lean" as the amount of fuel for a given amount of air. This is the INVERSE of the air/fuel ratio.

At 14.6 there is the perfect amount of fuel for the amount of air. If there is more fuel than can be burned with the amount of air - then the mixture is "rich." If there is not enough fuel for the amount of air then the mixture is "lean."

If I got this correct, thanks go to madmax2k. If I got it wrong . . . oh well!

 

that sounds right to me....

A/F ratio : larger number means more air, smaller number means more fuel

 

Oops! What a brain-fart! A/F of 14.6 = 14.6-parts air to 1-part fuel, definitely not the other way around. It's been a looong morning, Is it time to go home yet??

 

Close enough Max Gator!

Actually, "perfect" or stoichoimetric A/F ratio with gasolin is 14.7 to 1.

I think your plot is correct. This A/F ratio trace seems to be about how a manufacturer would tune a car. The ratio is very steady, and makes small adjustments to the rich side as the revs increase. This is "safer" as a richer mixture is less likely to pre-ignite or detonate with varying qualities of fuel and engine condition. Im sure a few hp could be coaxed out of it with an adjustable FRP and leaning it out some. But, it might only be a few hp and the cost of the FPR might not be worth it.

Im leaving mine alone.

 

I did a little reading and one reason cars in general run lean is for fuel economy and MOSTLY for lower emissions. However, you produce MORE torque(to a point) running rich vs. lean. Damn emissions!

 

Well, I don't know if running leaner equals better fuel efficiency but it makes sense. However, I think that generally you produce more power when running leaner - to a point. After which - kabooom. I leave it to the engineers to explain!