What is proper AFR for MS3?

[Matrix311]

Hey everyone I was wondering what proper AFR should be for the speed3? Right now my car sits pretty solid around 11.75 give or take a few tenths. Is this right where I need to be or would I be running to lean or rich? Is there a tuning article or another post that talks more about proper AFR settings for our car? I'm running the Cobb AP v1.03L Stage2+FMIC91oct map.

Please take a look at a recent dyno of my car. How does my AFR look? Am I running lean or rich or just about perfect?

[SSinstaller]

Your running about 10.75~1 for most of the run. If your trying to stay with an extremely safe tune stay where your at. If your looking for more power try and get closer to 12~1 or 12.5~1 but pay very close attention to knock..

[that.dude]

you are running rich... you could squeek out more by going to high 11's, and still be safe. 12-12.5:1 would be optimal, but again, pay attention to knock...

[Matrix311]

So the richer you are the less power you will have? If you run slightly lean then you gain power?

I'll stick with where i'm at for the moment. I'm running the cobb beta map and can't really change anything ATM. I was just curious how my run looked.

[socks]

12.5 is still "rich", as gasoline is stoich at 14.7

but yes, the leaner you run, you are getting a more complete burn, and making more power..

[socks]

I think your boost related to your map show your problem.

I think you have a boost leak. the stage 2+ maps dont run that rich i dont think, and you should have in upwards of 18psi... wheras you hit 16psi, and drop to 13 by redline...

[Matrix311]

Originally Posted by Speed3shon I think your boost related to your map show your problem. I think you have a boost leak. the stage 2+ maps dont run that rich i dont think, and you should have in upwards of 18psi... wheras you hit 16psi, and drop to 13 by redline...

Ya it's possible i have a boost leak. Any particular way to check and how to fix the problem? I did a log with my AP lastnight and ran it pretty hard and never hit 17psi. I have plenty of power and I'm not receiving any boost cut because it stays pretty solid through out the run.

[Haltech]

My car loves to be at 12.5. Ive had it there for 4 months now.

[gsrtype1]

Yeah 12-12.5afr is the sweet area for our direct injected speeds

[xandrake]

Originally Posted by Haltech My car loves to be at 12.5. Ive had it there for 4 months now.

What're you using to tune, Hal?

[socks]

kevin, when you run at 12.5 with the meth, are you pulling regular fuel or adding timing to lean it back out?

with my meth off, i run a 12.2-12.3 afr, but with the meth on it drops to 10s

[Haltech]

Lots of timing to lean the car out. There is no sense of pulling fuel when adding timing does the exact same thing on this car. When the AP software comes out, you will be able to add the timing where you need it. A nice trick is to give a 2 degree bump right at spool and the car bullets once boost comes on strong. When the live map switching happens, you could swap between meth tune and a reg tune. I dont see why a guy running meth would do this, but it will be an option. God knows, these valves and pistons need to be cleaned on a regular basis. You could easily add up to 8 degrees of timing running on methanol on a 50/50 mix and much higher then that if you go 100% meth mixture.

[Matrix311]

so what are some steps i can do to look for boost leaks on my car? Since i'm running in a safe zone AFR and my boost isn't spiking 18psi+ would having a boost leak cause possible damage to the engine?

[ElBartoRex]

Originally Posted by Matrix311 so what are some steps i can do to look for boost leaks on my car? Since i'm running in a safe zone AFR and my boost isn't spiking 18psi+ would having a boost leak cause possible damage to the engine?

do a boost leak test. Get an air compressor and hook it to the inlet (with the car off) pressurize the system to like 20psi and listen for leaks. readjust clamps/connections, test again until the leaks are gone.