Some food for thought: dyno AFR will always be about .4 of a point AFR leaner than real life. This is due to the car being still/static rather than dynamic air flow when driving.
The dynamics here are that when you are moving though the air while driving, the MAF will see more air flow than when static on a dyno. This will translate to more pulse width at injector = richer

So basically tune for slightly lean on the dyno, knowing it will richen up with load..


Comments please.

 

Yes, you are correct, dynos are a tad lean than on the street. They just don't "LOAD" a car like the street does.

I always shoot for a 12.4-12.6 on the dyno when I tune LS1s

 

Wouldn't that be kinda rich then on the street???

 

I wouldn't tune lean on the dyno, I would tune rich. If it is .4 leaner in real life, you would want to tune the car .4 richer on the dyno like Bill stated.

 

But Bill said the dyno is lean...

So I with that premise with load on the street it will richen up..

12.4-12.6 on the dyno would richen up to 12.0-12.2 in his line of thinking right?
Sounds pretty fat to me..

Please correct...

Or, with load on the street, will A/F lean out?

 

did u read you own post? "dyno AFR will always be about .4 of a point AFR leaner than real life" meaning if you run 12.6:1 on the dyno your gonna run leaner then on the street by .4 meaning on the street you'd be running 13.0:1 roughly.

 

Are we talking about the Dynojet AFR? That always reads about a .5 point leaner than my LM-1 or other handheld logger. That whole suction pump setup seems like overkill and it places the wideband sensor over 10 feet further downstream from the end of the tailpipes.

 

Dude,,, 13.0 is LEANER than 12.6
On the street you'd run RICHER...

Lean 13.0 --------- Rich 12.0

IF the dyno runs .4 LEANER than the street, that would mean that:

a 12.6 A/F ratio on the dyno (is .4 LEANER than on the street),
so street A/F would be RICHER, 12.2 right?

Again if the dyno is LEANER, with load on the street, the A/F would go RICH.
so, 13.0 dyno to 12.6 street
12.6 dyno, 12.2 street
Right??? Or I am going nutz here?

 

your confusing yourself...you want to run .4 richer on the dyno because it doesnt put s much load on the vehicle...meaning you'll run leaner ono the street just because thats what happens.