Hello,what is the perfect air fuel ratio for a 996TT with K16/24 turbo's which I run on 1.2 bar boost pressure? Some say 10.5/1 and others tell me 12.5/1..
Thanks...

 

10.5 is very rich. Personally, I would feel safe with a 12.0 , although some vehicles can tolerate a slightly leaner AFR, others cannot. Just depends on your comfort level. Leaner will produce more power ,but have less of a safety margin. Kevin

 

10.5 is to rich, you are washing the oil off the cylinder walls at that level. 12-12.5 is a good level to shoot for while tuning.

 

If you are tuning a car with an egt gauge, leaning cars out to 12.5 is acceptable if that is where the car is making peak power and egt's are reasonable.

In most cases you will find a sweet spot of .5 to .75 of a point a/f that will achive peak power. I try to stay on the rich side of that sweet spot to keep egt's in check. In most cars I tune, I find this to be ~11.5-12.3 ish.


Here is a good example of how a .5 to .7 difference in AF makes no addtional power.....so why not stay on the rich side and be safer.

btw...this is an audi s4

 

great info!!!

 

at 1.2 bars with 600 crank HP ur fine with 12.2s to 12.4s...

 

Yes, good info. Thanks all.

 

Great info Tony... glad to see you here! How's everything going? I hear you've been really busy lately and bet you have some interesting projects nearing completion?

 

Hey Alan,

Everything is great! That dyno plot above is actually Paul 0's car. He's kicking around here now as well (997 gt3).

We're crazy lately, full house, some p-cars trickling through as well.

I saw your project thread about your 996. Looks crazy...we have to get that up on the dyno and see how it compares to the s4 .

Ill give you a call tomorrow.

 

12.5 - measured yesterday on the dyno.

Craig

 

What dyno you use? Go to?