Went back to dyno and found success....

[RMS-Man]

Vehicle: 2005 Corvette 6 speed
Mods: Corsa cat-back and 160* stat
Attachment 267

My last visit to the dyno was very dissappointing. I went back to the drawing board and changed the PE tables to run 13.0 across the board and verified with WBO2 on the street. Then went back to the dyno. I made 2 pulls and the 2nd pull gave me 359.6 RWHP and 360.4 RWTQ. Then I did like I was told on here to load the stock tune and make some pulls while still on the dyno for a better comparision. (Same weather, same day, etc.) I made 2 pulls with the stock tune loaded and the numbers were 358.2 RWHP and 353.5 RWTQ. Not very impressive on the peak numbers, but that is not the whole story. Take a look at the gains from 4000 to 6000 rpm.

Attachment 265
The gains at 4300 rpm were 15 RWHP and 20 RWTQ.
I thought the car pulled much harder after I finished tuning it on the street. Here is the kicker. On the stock runs I figured COT kicked in and made it go pig rich and lose all that power, but what I found on the data log was the coolant temp was over 215* during the runs and the VCM pulled up to 7* of timing right at 4000 rpm. The recovery rate was very slow as well. It took 8 seconds to get back to 0* retard from there. In comparision during the tuned run coolant temp stayed at 183*and I saw 4* of retard at 5100 rpm, but it went back to 0* retard in 2 seconds. I'm attributing this to my changing the KR Decay Recovery Rate to recover 3 times faster from 2500 to 7000 rpm. I also made the KR Attack Base Rate a little less aggressive from 2500 to redline. Altough I never saw any KR during my street tuning logs after dialing in everything.

I also had the WBO2 hooked up pre-cat during all these runs and the AFR during the stock tune run was about 13.4 from 2600 to 4600 rpm and then it dropped to 12.7 from 4700 to 5600 rpm and then was 13.0 until 6500 rpm. I was surprised to see the AFR with the factory tune look so good and not really that rich. During the tuned run the AFR was 12.9 to 13.1 from 3200 to 5000 rpm. Then 13.2 to 13.4 from 5100 to 6500 rpm.

Positive or negative input welcome. What do you guys think?

Thanks HPTs for an amazing product and for all your fast email replies with excellent tech support. I can't wait to do a few more vettes and start spreading the word here in DFW what Resurrection Motor Sports can do with tuning. (Thanks to HPTs of course.)

[S2H]

well street and dyno are apples to oranges...
in my experience..if I go to th edyno first..I can dial in the AFR that the car is looking for...
lets say I do t for a range of 12.7~13.0 varying slightly with different rpms so that I get 12.7 at peak torque and 13.0 at peak horsepower

when I go to the street..my wideband in the pipes is not going to be correct..not going to be the same..the street is totally different than the dyno..
when I hit the street it will be leaner than when I was on the dyno......thats a big problem...
so I retune the A/F on the street..again..I have already set my PE..so I am going to be adjusting my AFR using the VE table and MAF table...I do this on teh dyno as well..set PE and do it in MF and VE...but the #'s in those tables are usually considerably lower when I am on the dyno ..
so MY pe stays the same and I have it set to = what I want it to command for air fuel...


go to the track and do a pass on the stock tune.then put in your new one...I'm sure you will run faster with the new one

dyno racing is for garage queens
track times are for real racers

[RMS-Man]

Thanks for the info Scott.
I thought you only made tuning adjustments on the street and not the dyno.

[S2H]

I like to use the VCM controlls to push the AFR around till I find out where peak torque occurs...looking at my wideband info from the wideband in the bung...
then I do the same thing for HP...
once I know what the car likes..then I set the PE to command than..

after that..its off to th estreet to adjust VE and MAF...
I leave it set for the street..but I use the dyno to find out what the car likes for HP and TQ afr as they are not usually teh same value
plus it helps me find where the torque peak is and where the HP peak is so I can tune accordingly...

I use it as the first tool in my aresenal...
then I tune on the street to dial it in correctly

[RMS-Man]

Now that is an excellent way to utilize VCM controls. Thanks for sharing that info. I'll have to try that on the next one. Also, I will try to get one out to the track for a stock vs tuned run.