Street tuning vs Dyno tuning?

[Mep_q8]

I just took a trip down to the dyno today to get some runs and I wasn't very pleased..with the tune i created from street tuning with my WB peaked at 221whp and 230tq (spent countless hours playing with the VE tune to get my AFRs from 14.6 @ idle to a 12.7 @ WOT) on the road, my car felt like the front tires were loosing grip cuz of the amount rear end dipping it was doing....

now at the dyno, the owner just played around with my truck for not even 5mins... set the stock VE back in place, changed the commanded AFR to hit at 13.4 and changed a few of the MULT vs RPM values... on the dyno run and it hit 230whp and 232tq.. similar to what i hit with the Jet Chip Stage 1...

Now when i drove the car off, at WOT i didn't feel as much power as i did with my previous tune.. could there be a reason for this and why would it happen??

I've heard stories about Dyno tuning and how they only measure for peak HP/TQ and not the net.. the dumb ass i am forgot to pick up the dyno sheet so ill pop round tmrw and get it printed off and post it up.. needless to say, im well annoyed coz i thought i got my VE pin pointed perfectly...

[zq8bob]

VE tuning is not about horsepower.... its about driveability... Its about a smooth idle and smooth throttle transistions... and it's not the kind of thing you can guess at. It needs to be VERY precisely measured..

PE tuning and timing is where power is made.

[Mep_q8]

the thing is though, when i tuned my VE, i was using it to tune my AFR.. i got it the best i could, and about 30 different tunes later, my AFR was where i wanted it to be...

Now since u brought the topic up about PE tuning, once in this mode, your saying the VE tables have nothing to do with anything at WOT?? My spark advance on my HO are much higher then the HO (PE) values...if i changed them to be similar to my normal HO could i risk blowing up my engine?

[S2H]

heres the important info you need to know....
you tune on the dyno first to find out what AFR and what spark your vehicle likes...
then you go to the street and tune the VE table/MAF table to match the commanded AFR that you got in the dyno..

its extremely important that you command exactly what you want in the PE table and then correct the VE and MAF to match...

all of this with a wideband of course

bascically you cant simulate real world airflow on the dyno..no matter what you do...it just aint happening...even with millions of dollars GM has to still drive it on the street to get it correct...

so you go to the dyno and get 12.8AFR at WOT...
when you get on the street suddenly its 13.8 on the street
why..cause suddenly you now have a bunch more air that you didnt have on the dyno..


what happened with you is you probably had a good tune....
you went to the dyno and you thought you set AFR toa specific
value...which now shows rich on the dyno cause theres not enough airflow..so the dyno guy leaned it out.and now the values are lean for the street...

you following???

if not...I can explain it better with some pictures if you need me to..but it should al make sense...

dyno and street are VERY VERY different...
if you want High dyno #'s tune it in the dyno...
if you want real world horsepower..do you A/F on the street/track

[Mep_q8]

ok weird.. just got my dyno sheet from the garage... seems like the dyno tune was better overall even though it doesn't feel any better

I remember just before the dyno i set the PE enrichment mode (Hp Tuners) to come in at 2,000rpm.... on my initial tune it was previously at 4,750rpm...this might be why my street tune on the dyno run isn't so impressive....

[MeentSS02]

Holy fizznizzle shizzle...tell them to set the smoothing to 5. That makes my eyes hurt

[Blandmiller]

I agree with Steve. Set the smoothing to at least 3. Are the A/F numbers correct? It looks pretty lean for WOT high RPM.

I also noticed that they are using STD correction and not SAE. These numbers will be slightly lower when corrected to SAE.

[zq8bob]

I keep forgetting that your a speed density setup Trailblazin... And that the VE tables play a larger part for you than the MAF setups... So yeah, in your case, VE will play a larger part.

Basically, now you wanna take what you learned on they dyno and apply it in a real world situation. If your truck liked 12.8 on the dyno, dial it in on a street tune to that AFR.