what is a good afr for an HCI car?


Cookies should never be DUNKED!!!
Aug 3, 2004
atl ga
I tried searching but I didn't get much. What is a good AFR for an HCI car. It was flat at 12.9 all the way across but the tuner said it could make more power running around 12.1. Yall agree? If so I'll bump the FP and timing tomorrow to see how the car reacts.
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yeah 12.1 is way to ich on a NA car. I bought afr 185cc for my car when it was a HCI engine and to be honest the heads are to big for a 302. A 302 doesnt really flow enough air to reach the HP levels those heads are capable of producing. If you plan turbo/ supercharger then 185cc work great. If you just want to stay NA I would go 165cc heads
12.9 across the rpm band is an accomplishment!
In my experience I've never seen a single pull on an engine dyno nor a chassis dyno where it was that "controlled".

+3 IMO you are good to go right where you are. I also would expect you to gain a few more at 12.0 and some more advance IF you're not already there.

When do you have all the advance "in" at? and how much is it?

Post up your run sheet, it would make it easier than asking/answering back and forth.


I'm used to seeing the basic tune setup on the run sheet. My bad for assuming there would be the timing, fuel pressure, egt, cht and what not on it.

I do see one serious issue you have.
See how your power and torque band get erratic from 5200 to 6000? That IMO and I'm pretty sure I'm correct is... valve train instability. If I were in your position, that's what I'd be concerned with because it definitely isn't your A/F ratio.

Good luck