mac10chap

ok, i have done a search on here and still cant find an answer my question.When i got my car dyno tuned quite some time back, my shop guy ended up leaving my A/F Ratio at 12.8. Now, i thought that was pretty good but lately, i have been reading people talking about having and A/F of anywhere between mid-11's to mid-13's. Does the rich vs. lean differ in N/A and Supercharged cars? Basically, I am wondering if my A/F ratio could be adjusted either way to try and get some extra power out of it.

Right now, I am dyno'd at 325RWHP/340TQ

jrm1900

The information you posted is what I have in my head as correct, in order to get more performane you'd have to lean out the mixture and it can lead to detonation, overheating and very expensive damage to your engine, I'd say you are in the upper range of the safe side so I'd leave it like that.
SC or NA use the same principles when it comes to air fuel mixture but detonation occurs at different points because in the case of SC the air charge get's hotter as you increase the boost thus the use of intercoolers to keep it under control.

mac10chap

ok, thats what i thought, just got a little doubt for a minute there. thank you for clearing that up. I will just leave it at 12.8 then. My car has been running great forover 2 years now with that dyno tune....if it aint broke, dont fix it!!!

07SCGT

N/A or S/C I would think 12.8 is extremely High. JDM was extremely concerend about my mid 12's and they told me to order a new fuel delivery system. I was actually hearing very very slight pinging at 4000 + RPM, My dyno showed that at 3700 and higher I was leaning out drastically, going from 11.2-12.9, in a matter of 1000 RPMs. I played it safe and JDM played it safe and gave me tunes that kept me in the low-mid 11's.

mac10chap

see, another different answer...*doubt sets in again*

07SCGT

I have an idea, upload your Dyno run and let's look at it. Make sure to show the Air/Fuel on it..

jrm1900

Mac10 said his car has been running fine for the last 2 years, honestly I cant think of a reason to be concerned, facts beat theory (IMO), and then we are talking about opinions again what is safe for some is critical for others, If I was a tuner I'd play very safe too as I dont want people knocking at my door blaming me for blowing up their engines and asking me to pay for the repair

07SCGT

Another thing might be that I am running 91 octane, that's all they have in AZ. I try to make it further down the road (close to the race track to get 2 gallons of 110 every once in awhile. Chances are if your not hearing knocking or pinging going on at the higher RPM's you are probably safe. With a S/C I wouldn't want to be higher than 12 max though. I have heard that from numerous people, and tuners not just JDM.

07SCGT

This is my AIR/Fuel that JDM that was asafe for me. Again, I have a blower and all I can get in Arizona is 91 octane,so maybe that makes it so I can only run in the 11's safely without pinging.

05 Ricky

If you are N/A you want your air/fuel to be any where from a 12.8-13.0 air/fuel ratio at the tail pipes, if you are forced induction (turbo, supercharged) this cars run best with the air/fuel set around 11.5-12.0 air/fuel ratioAre you N/A? If so 12.8 is dead on the money for the best performance out of these cars. Lets put it this way...and thing over 13.2 air/fuel on these cars is asking for trouble. And anything over 12.0 air/fuel for a surpercharged car is asking for trouble as well.