For Example: 15.0:1 = Lean 14.7:1 = Stoichiometric 13.0:1 = Rich Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.[/QUOTE] Unless I am missing something here, 13.0:1 is still way lean from my understanding
The first number is parts air, the second number is parts fuel. Fewer air parts, 13, to the 1 means it is rich.
I thought a good number to shoot for was around 12 under a load...! dang....just when I thought I had a handle on the a/f deal. lol
This information is correct in a perfect world. A "hunting" 14:7-1 is great when highway cruising under steady throttle (No load). However, our engines do NOT have an efficient combustion chamber and need to be on the rich side to make smooth, strong torque and detonation free H.P. at high R.P.M. YES, too lean by about a full point. especially from 4500 rpm to 5500. It does however "nose over" nice at redline. Yes. 12.7 / 12.8:1 would be ideal. 12:8-1 and richer to keep combustion chamber temperatures cooler. Add up to what some say +23 to +25 total ignition advance and KEEP the ratio at 12:8 or just under and your engine will make great N/A power. Unless I am missing something here, 13.0:1 is still way lean from my understanding[/QUOTE] Yes. 13:0-1 is still too lean at WOT. Cheers Guys!
Again he dynoed on nitrous plugs and sounds like overdrive so it surely wasn't an optimal set of pulls. Still unsure why one sheet reads one way and the other opposite? Anyone else see that?
Scott, the dyno sheets that were close-up, were Stealth78's...not mine. we were comparing. His looked good to me. Here is mine.
Duh, I don't know how I missed that. I don't like either! His starts off lean and fattens up nicely. You're starts out nice and leans out too much. Both are scary situations but I'd expect your numbers to be close to Stealths on NA plugs and tune corrected.
We'll We'll get it. Between Justin, Torrie, Scott and everybody here, we'll, or I should say, they'll get it. To much knowledge not to. Can't wait to get it cammed and dyno-tuned Thnx everybody....!
Got it fixed up, 488whp/486wtq with JMB/PBJ cam and minor tune changes. That's through unlocked 3000 stall converter, 93whp and 84wtq gain over what it made before. I'll post a new thread with dyno chart Monday. Justin
Question? What does the stall of a converter have to do with max output on a dyno? I am under the impression that stall only affects launch from a standing start. Just wondering. Personally, anything without a 3rd pedal is boring to me.
I have no clue. Maybe somebody can elaborate. All I know is, my truck sure runs alot better after the new camshaft got installed.
Justin will have to elaborate on the "unlocked" converter. I wasnt there when they dyno tuned it, so I have no clue what they(Justin, Torrie and Perf. by Joe) did. Hell....had I been there, I'd prob. still been lost..! lol