Quote:
Originally Posted by phelan
The AFR is also a little on the rich side through the entire run. Not sure since I'm still relatively new to all these, but a tune could probably help out a little here.
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Phelan,
Your Air Fuel Ratio is NOT too rich. It is on the leaner side. The higher the number the leaner the A/F. The lower the number, the richer the A/F.
Optimum A/F for a naturally aspirated car is: 12.6:1-13.0:1
You are right in the optimum area.
Now, this makes sense that you car has leaned out. When you relieve back pressure like you have you lean a car out. Now, your mass air meter is designed to compensate for modifications. It does but only to an extent. I am looking at your dyno charts and I can tell you that the car leaned out. They are higher than the previous numbers. Also one thing to keep in mind, A/F numbers will be a different number the further back the reading is taken. The optimum point to take an A/f ratio reading on a dyno is before the catalytic converters. So to recap, I know that a set of aftermarket cats and cat back exhaust system such as ours WILL NOT lean a car out to the point of DANGER. However, it doesn't hurt to get a car tuned after the fact.
The popping noise you hear sometimes on deceleration is the freed up back pressure due to the free flowing exhaust.
One more thing to add, even though you are on a dynapak you are still hooked up to the axles, that is still considered a rear wheel or (at the tires reading)! To record flywheel power you have to dyno an engine on an engine dyno out of the car.
Call me if you need anything...
Thanks, Tony