I always thought engines made the most power with an A/F ratio that was borderline on detonation or at least on the lean side. From what Ive been reading in this forum running the engine on the rich side makes more power; at least on our engines. Am I not understanding something?

 

I have heard anywhere from 12.6 - 13.3 : 1 is optimal for best power on our cars (LT/LS1).

Do a search and you will find lots on the subject. I also know from experience that a bit leaner at the top end produces more. NOT MUCH. But more, however not enough for me to lean out my car at 6K RPM.

Ben

 

I've had one pretty well known local tuner tell me 12.2-12.3 on LT1's is what he's found best. I've found 12.8-13.2 to work pretty well.
That being said, I've never found a huge difference between 12.2-13.2.

 

Correct..

You'll find maybe very little hp going from lean to ideal (13.0) but you'll find a good bit of power going from rich to ideal.

You can find more torque at other AFR's than 13.0 and when dyno tuning vehicles (especially trucks) I'll have 2 different AFR's I want to start from and end to. Really killer how it works. Recently using that technique I picked a truck up 8rwhp (only made 190 at the wheels so thats a good deal) but more impressively I got 22rwtq finding a different AFR in the lower RPMs.

The good thing too is at the ideal AFR the car will make good torque and be less tempermential to weather conditions and ultimately less likely to spark knock.

 

Hmmm...on LT1's I've seen huge gains going from lean to ideal. How about 60rwhp on a 380rwhp car.
Never had one be extremely rich and have to lean it out though.

 

Just like the car doesn't preform best with timing fixed at a certian AFR threwout the RPM range it also doesn't preform absoulutely best with the same AFR.

What I'm talking about though is going from a certian afr at 3500 to a 13.2 or whatever the car is pulling best at at 5500rpm.

I'm doing a 400 SBC pickup truck today. IF I can talk him into getting on the dyno I'll post the AFR chart vs. HP and tq and you'll see what i'm talking about. I'm not sure if he will want it on the dyno, most truck guys do not. They are more concerned with just how it drives.

 

there is definatly truth to what ROOSTER is saying about AFR at different RPM pionts. AFter only picking up 17 RWHP on the dyno we adjsuted the lower RPMs AFR and found 38 RWTQ !!!!! So when you guys dyno tune your cars make sure you take it to a tuner that knows what hes doing !

 

Thanks for backign me up.. its hard to share secrets without sharing so much. You got to still leave a little for the learning curve