My car is on the dyno right now. Have made a few passes and have a consistant AFT of 12.5 from 3000-4500 RPM this is on 93. This is consistant with other vishno dyno graphs using a sniffer in the tailpipe but the folks here are concerned that this is a bit lean since my peak torque is hitting right at 3700.

I added 4% fuel in this range and it smoothed out the curve but I lost 10ft/tq from doing this. My question is what is a safe pump gas AFR in this RPM range? I road race the hell out of car so it sees alot of abuse in this RPM range.

I'm also getting a consistant dip in power at 6600 RPM. AFR and BOOST is rock solid. How much timing do you recommend I yank out to combat what I suspect is a knock event?

 

Do you have a HF cat? Try -.5 less in the suspected knock area. That seemed to work on my car.

Also, adding fuel will retard the timing. Which is why you lost 10 ft-lbs. If you want that back add some timing in those areas. Watch for knock though.

 

I have a testpipe. Thanks for the tip on timing!

 

Well I ended up tuning for 11.5 to 1 through the entire powerband.

I added timing and boost where I had previously felt I was dangerously lean and actually ended up making more power and torque than before.

The one thing that really opened my eyes was the difference a knock event makes on the curve. When the ECU pulls timing it yanks it hard! I had consistant knock up top at peak HP. It was actually causing my HP to drop 20WHP. I ended up plulling out .5 degree of timing 1k rpm before the event then 1 degree at the event and was able to eliminate the knock and even picked up my peak HP.

I may be bucking the vishnu system but I definately didn't feel safe running 12.5 to 1 on pump gas at max torque even though Shiv himself claims its safe.

Taken from here: https://www.evolutionm.net/forums/sh...d.php?t=170548