Air Fuel Ratios

[TurboMike]

I'm setting up a FAST on a GN with ported heads, 75lb, 210 roller, PI 3200, TE63 with .82, V2. The car is a little doggy but comes on like a bandit above 15psi. I'm not sure if it's just the car or my a/f ratio incorrect. I have the VE numbers running within 5-8%. My A/F ratio goes like:

At 5 psi- 12.7
At 8 psi- 12.5
At 10 psi- 12.3
At 12 psi- 11.9
At 15 psi- 11.8
At 20 psi- 11.7

Do I need to richen it up some?

I have my timing real low. It's not MY car so i don't want to pop. Timing at 20psi is around 19 degrees, with 110 octane.

 

[TurboTR]

Well if it's a .82 Garret 3 bolt then that's probably to blame. I found that a .68 4 bolt worked best on my 235" engine. The .81 was too big really, compared to the .68 at least. This with a real 3000 stall.

That a/f ratio progression looks ok to me for starters.

PS good plan in general on being conservative with the timing IMO. With c16 that might be a bit overly conservative IME, but with 110 who knows. If you lived around here we could put the cylinder pressure gear on it and answer the question for sure though ;-)

TurboTR