I had my 408 dynoed a while back. It is N/A. The car made 400 to the wheels. I was looking through a dyno sheet and notice the a/f was 13's the whole way up then in the 5000 rpm range it hit 14. I just want to make sure this is safe. I'm pretty sure if it wasnt my tuner, would not have let the car go. I searched but couldn't find anything. Am I ok? Thanks.
Safe A/F For N/A 408
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My car was tuned with the old motor. Afr was 13 all the way through, which my tuner said is what he likes to see with a n/a street motor. I'm not well versed in this area, but i believe i remember reading some tuning literature that explained 14.7 is considered to be the "perfect" afr for making the most power possible. However, given climate change, elevation changes, fuel variances, etc, that safety window is left to ensure no engine damage occurs. I think i would contact my tuner and inquire as to why it is leaning out. Your fuel system may be tapped out.
Joe
Joe
air fuel in the 13 range is plenty safe for a N/A motor. I would never however have a/f in that range on a boosted or nitrous motor.
I'm not crazy about the a/f being in the 14 range but the only way to tell your actual a/f is with a gauge or by reading the plugs. Dyno's don't always give the real answer either. Where your a/f may be one thing on the dyno, under load and at 100mph they may not and probably are not the same. An a/f gauge would be my next purchase if I were you.
Hope this helps..
I'm not crazy about the a/f being in the 14 range but the only way to tell your actual a/f is with a gauge or by reading the plugs. Dyno's don't always give the real answer either. Where your a/f may be one thing on the dyno, under load and at 100mph they may not and probably are not the same. An a/f gauge would be my next purchase if I were you.
Hope this helps..
I just found out I was sent the wrong dyno sheet. The a/f for the rpm range was 11.3. My tuner was having trouble because the car was spinning the tires on the dyno. He told me to get drag slicks and come back. He can pull more power out of the car. Is 11.3 too rich? Theres no cats on the car. The a/f was taken from an o2 bung in the h pipe.
I am starting to question your tuner, no offense.
Never and I mean Never run slicks on a dyno!!!! They want to grow as speed increases and when the car is strapped down they can not do this. The tires become deformed in a hurry. I have personally seen the damage an exploded slick has caused to a car that was on the dyno with slicks. Not to mention the dyno operator wound up in the hospital from the shrapnel of the car, nothing life threatening but injured non the less.
11.3 is on the bottom end of where i would want a blown or nitrous car, but never an N/A car. You should be solidly in the 12.6//12.8 range in my opinion to be absolutely safe.
I have drag radials on my car and we made 1,327 rwhp and had zero issues with tire spin. Even street tires at the 500 rwhp range should not spin on the dyno.
Never and I mean Never run slicks on a dyno!!!! They want to grow as speed increases and when the car is strapped down they can not do this. The tires become deformed in a hurry. I have personally seen the damage an exploded slick has caused to a car that was on the dyno with slicks. Not to mention the dyno operator wound up in the hospital from the shrapnel of the car, nothing life threatening but injured non the less.
11.3 is on the bottom end of where i would want a blown or nitrous car, but never an N/A car. You should be solidly in the 12.6//12.8 range in my opinion to be absolutely safe.
I have drag radials on my car and we made 1,327 rwhp and had zero issues with tire spin. Even street tires at the 500 rwhp range should not spin on the dyno.
A N/A 408 making 400rwhp shouldn't be spinning the tires on the dyno either? I've seen 1,000hp turbo cars break them loose on occasion, but at those power levels, i'm guessing it's operator error? Are your rear tires completely worn out? Otherwise, tell him he needs to tighten the ratchet straps or wash the oil off of his dyno rollers. lol
65ShelbyClone
Founding Member
Yes it is and by a large margin.
With all this being done on a dyno, the correct answer to your original question is "give the engine what it wants." The best AFR is the one it makes the most torque and power with and I think yours could do with less fuel.
