whats an ideal A/F ratio to tune for on a H22? My shop is telling me they will aim for 13.8:1 when my car gets on the dyno - disregarding EGT's, and all that, I was still thinking that might be a little too lean for optimum power. suggestions / comments?

PS - so far its a stock H2A with stock internals (10.6:1) and 4 degrees of ignition advance.

 

It's ok to run a little lean, that's where you'll make the most power. Just don't push it!

 

13.8:1 is rich not lean. perfect a/f ratio is 14.7:1. so you have 13.8 parts air to 1 part fuel instead of 14.7 parts air to 1 part fuel.

 

13.8 is a shade towards the lean side, even for an N/A car. Ideally, you want 12.5-13.5 for power and safety. This range should offer enough safety margin to account for changes in atmospeheric conditions, temperature, and elevation - all of which will cause you A/F ratio to vary in real-world operation. You don't want it over 14 at any point. When you start getting too lean, the ECU starts retarding the ignition timing (you lose power) and/or you get detonation (could cause engine damage).

Andrew

 

Like, aklucsarits said 13.8 is a little lean you might be able to pull it off. What octane do you have down there? What are they using to tune your car?

14.7 is the perfect air fuel ratio for emmissions and is only used in closed loop, cruising conditions. It has nothing to do with tuning for power or safety.


[Modified by DirtyLude, 6:56 AM 4/4/2002]

 

the tool is just a VAFC.

it will be dyno-tuned w/ a wideband O2 sensor. down here, we have 93 octane.

 

actually, I was just looking for someone who dyno-tuned their car, and could let me know about what A/F ratio they made the most power at.


[Modified by JDM LUDE, 8:19 PM 4/4/2002]