GM 8.1L Allison Combo

[Johns98TA]

Hi Guys,

I have an 05 2500HD with the 8.1L allison combo. The truck is all stock, and I want to optimize the engine and trans tunes for performance (without sacrificing longevity). Would any of you be willing to share a tune file with me so I can see what changes you typcially make to a stock vehicle? I have HPT and I have tuned my 98 WS6 Trans Am (LS1), but I have no experience with the L18, drive-by-wire, Allison, etc...
Also feel free to post suggestions, experiences, etc
THANK YOU in advance for any and all help you provide me.

John

[Bill@HPTuners]

I don't believe our software can tune the transmission module on these vehicles. You should be able to read the pcm without much issue though.

[Johns98TA]

Bill I also noticed that the VCM controls in the scanner do not seem to work. I can do all of the basic scanning, but I am not able to use any of the VCM controls. Am I doing something wrong, or do I need to change something to get this to work on the 8.1?

[Bill@HPTuners]

Engine VCM controls should work as long as we've already mapped your operating system, not sure about transmission vcm controls on that vehicle in all honesty.

[Johns98TA]

Bill,
The engine VCM controls are all greyed out and not useable. The trans controls are also greyed out and appear to be for a 4-speed. The scanning functions all work great, however.

I've got VCM suite version 2.1.x, so I'm going to upgrade it tonight and see if that cures the prob with the engine controls.

Thanks for replies; I will post back here with updates as I make progress. I sure hope others chime in with suggestions for this beast. I am not impressed at all with the stock tune, shifting, etc....

[LSxpwrdZ]

Bump this old thread up. I've got a 2007 8.1L on the dyno right now that I've read successfully with version 2.22 but it gives a vin/os mismatch. Open the tune in the latest beta and edit the calibration and go to flash it and it give me a "tcm write protocol was not detected". Is the '07 not tuneable? I don't really need TCM stuff just at least engine stuff to be editable.

[LSxpwrdZ]

Figured it out... pull the TCM Fuse to flash the PCM.

[superwagon]

Bump this old thread up. I've got a 2007 8.1L on the dyno right now that I've read successfully with version 2.22 but it gives a vin/os mismatch. Open the tune in the latest beta and edit the calibration and go to flash it and it give me a "tcm write protocol was not detected". Is the '07 not tuneable? I don't really need TCM stuff just at least engine stuff to be editable.

Interested in hearing what kind of gains you make! Mine seems to like a little richer afr and it doesn't seem to like very much timing at WOT. Not much info on this engine out there but it does repond very well to tuning.

[LSxpwrdZ]

Our dyno is on the stingy side however I was shocked at the results. I believe the stock numbers would be higher had the LTFT's learned the truck prior to making a pull with the stock tune. It was stupid lean under WOT where I had cleared the fuel trims prior to running the truck on the dyno. It made a whopping 202rwhp in open loop on the stock tune. This was with an AFR leaner than stoich as well as little to no timing. I ended up getting power with a tune up to 270rwhp running right at .86lambda and 20.5* timing at peak torque. The truck ran much much smoother and seemed to pickup lots of power and throttle response. The VE table was way lean on this truck for whatever reason. I figured the MAF was off due to the CAI the truck had on it. Really would like to dyno one stone stock with no mods to get a better idea of what they make but this is what I had to work with.

[superwagon]

Nice work, I bet your customer was happy! Sounds about the same as I am commanding for fuel and timing at WOT. Makes me feel a little better to see your timing is similar to what I have been able to run. Mine is a suburban with the 4l80 and my tuning has all been on the street, the one time I had it on the dyno I found out it was a inertia only so I couldn't really dial in my ve and timing. It was a dynojet and my stock pull it never went into PE and it put down 260hp, after we loaded my street tune it did 320hp. Not very confident in the accuracy but the gains were impressive for sure!

[LSxpwrdZ]

Same deal with this one. It never went into PE and where I had cleared the fuel trims it made it run even leaner.

[LEDbetter]

I ended up getting power with a tune up to 270rwhp running right at .86lambda and 20.5* timing at peak torque.

What rpm were you making the peak torque at? And what octane gas was used?

[LSxpwrdZ]

Sorry for the delayed response, I need to take a look at the graph again cause I don't recall currently.