Ready to tune, need some advice!

[kapower06]

OK so I ended up getting a horsham dev. stage 3 chip, along with some skyline 444cc injectors and used my n60 mafs instead of the N62 mafs, but not to worry I have a SAFC2 to change the mafs setting and fine tune the chip. I have everything in and running, installed the chip myself (fun soldering on a PCB, 1st time) wired in the new MAFS and installed the injectors, so tomorrow im going to a local tuning shop and doing an hour long session to test and tune to make sure its safe, my question is, what a/f ratio would you guys feel safe tuning to. Its gunna be around 10-30* out side for a few months, running an ARC intercooler, and 93 octane. I was thinking around 11.7-12/1 for full throttle all out, or should it be more around 11.5/1? Also whats safe for light-partial throttle crusing around 3-3.5 k rpm highway crusing? I can change between two tunes using the SAFC. Thanks guys.

[c-rad]

I don't have much experience, but it seems MOST people shoot for around 11.8:1 for a "safe" tune. I am jealous you got that Horsham Stg 3. I want one BAAAD.

[kapower06]

Yeah I've been eyeing one for a while now, and one came up on ebay ended up paying 280 for it though. But it runs good and has no problems except for when I first start the car it doesn't idle and will die but once it warms up its fine, I think its the IAC motor.

[float_6969]

Anything more rich than about 12:1 is wasting gas. You can run more timing by running more rich than that, but the motor is less effecient that way.

Here is how I tune; Since you're using a SAFC, set the base timing to 10°BTDC. Then get the AFR mostly even across the board (ie; 11.5:1 from 3K-Redline). I don't know if there is a way to do this, but with the SDS there is a general lean/rich knob that will add a certain percentage to the basic injector duty cycle. This allows you to add or remove fuel from the entire fuel curve. Starting at 11.5:1, lean the mixture until you make peak HP or start to detonate. Don't go any more lean than 13:1 (it's unlikely you'll still be gaining HP by going that lean, but just incase). From my experience, you'll end up around 12.5:1 as your peak HP. Once you get the peak HP fuel worked out, start adding timing back in via the CAS that you retarded back to 10° earlier. Do it in 2° increments. When you audibly hear knock, back out of the throttle immediatly, and then pull the timing back 3°. Don't go past 15° base timing.

That should make for a powerful, effecient, and safe street tune.

[c-rad]

12.5 seems way too lean to me. Scott Avoy (enthalpy tuning) did a custom ecu tune on my friends SR and he was running 12:1 on 100 unleaded (8.5:1 compression motor, 20 psi, T3/T4 50-trim). Made 445 whp and his EGTs maxed out at 850*C
Modified by c-rad at 8:46 PM 12/18/2006

[float_6969]

Maybe it's my high compression?

After looking at all the dyno's in the sticky, most guys are around 12:1.

In all honesty, what the AFR'S are doesn't matter. If it makes peak HP at 11.5:1, leave it there. If it makes it at 12.5:1, then leave it there.

The FIRST thing I learned about tuning an engine is not to try and give the motor what you think it needs.

Give it what it wants....