Ponchorello

I have been logging/tuning my car (2005 A4) with efilive and an LM1. I have the car at 24 degrees timing and 13.5 - 13.6 AFR. I dont get any KR with this tune. Would this be considered safe for N/A?


Mods are:

1 7/8 Headers
160 Tstat
Cam
no cats
Vararam

BTW...it runs like a raped ape.

EuroRod

I've always thought that a na engine operating at WOT had a AF of between 12.5 and 12.7 for best performance. $0.02. Good luck

xtacy187

I dunno about EFI but I use HP-Tuners.. If there's a "Fuel Enrichment @ WOT" multiplier, see if you can richen the air/fuel mix to around 12.9~13.0 for WOT..

Joe_G

I am a tuning newbie...so I'll start with that.

But from what I've read and heard, I would NOT run so lean!!! That is danger zone lean I think. I know a dyno jet screen will flash red if it gets that lean under WOT. I've seen 13.0 to give high dyno numbers but I run 12.7-8 or so to be safe. Did you adjust it to be that lean or is it just running that lean from the LTFT correction due to a stock tune and headers? I'd stay out of it until I richened it up a lot if I was you.

Maybe someone with more experience than me will chime in.

Ponchorello

I adjusted my A/F ratio via the PE table. Maybe I should fatten it up a tad bit but man it runs strong.

I know Jim Hall likes to tune his cars in the 13's for track use.

tjwong

When I am tuning for the street I tune for a 12.5 AFR that is a safe AFR for street use. As an example the other day I was finalizing a head and cam job, it was 103*F in my shop, IAT was 99*F, with a 12.5 AFR I was able to pull out 405 RWHP. The very next morning the ambient temperature had cooled to 69*F, IATs dropped to 70*F during the dyno test, I made 413 RWHP, AFR raised to 13.1, so I dropped the AFR back down to 12.5 and the final numbers were 415 RWHP and 376 RWTQ. This shows you that if you tune at a lean number at higher air temps you maybe very lean as air temps drop and air density rises. In my case where it was very hot that evening, even though it cooled off I was still safe, had I tuned for 13.2 that evening my AFR would have been dangerously lean when the air temps drop and air density increases.

Joe_G

Tom, thanks for stepping in! Always good to read about your results.

What do you consider a "safe" AFR for WOT?

gtodoug

Very tricky subject matter here. At 12.3-12.5 the car is very safe all around. Generally speaking 12.8-13.0 will make very good power and be relativley safe providing it is tuned properly. However as Tjwong suggested it can change with air density due to weather changes. You really need to be carefuel from there on out. So many things come into play here like:

Is the car still making power after leaning it out?

Will the car sustain the power without knock under load at that AFR?

Where are you taking your AFR reading at?(pre cat, after cat, tail pipe etc.)

What rpm range are you in that you are tuning afr?

What type of driving is the car going to see primarily?

Are there cats on the car?

Are there any adders/multipliers in the tune to that helped derive the final AFR?