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6l90 behind a 6.5

ak diesel driver

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So a buddy of mine is getting ready to put a 6l90 behind his 93 6.5. Says he'll be able to tune it with hptuners. Evidently it about 2 1/2" shorter than the 4l80 but he thinks between his 2 slip yolks he won't have to lengthen the rear shaft but will probably have to shorten the front. The other hurdle is torque converter heights are different but he has 2 options. 1 is a custom height converter the other is a shim for between the engine and bell housing which someone already makes. Should be interesting to see how it comes out
 

THEFERMANATOR

FRANKENBURBAN
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It takes alot more than just hptuners to make a t43 work. The 6l80/6l90 uses a T43 TCM that is mounted to the valve body. It uses all high speed GMLAN for data coms. There's only a few wires that even run to it. The only way I know to make one work is to either use a compatible GM ECM from a gen 4 or 5 LS, or PCS makes a gateway that converts other signals into HS GMLAN that the T43 can understand. Unless there has been monumental advances at HPTuners in the last year on T43 development(I doubt because EFILIVE's board would be lit up with request's for it if HP had it), he's going to run into a $900 hurdle for the PCS 2650 gateway box and harness.
 

Rockabillyrat

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THEFERMANATOR is correct. You will need the PCS box to make it all work. You can do the tuning with HP tuners. But need the PCS to make everything talk to each other.

They put the 6l90 behind the duramax in some of the Van's. I believe the LMLs. I thought someone said that converter will work on a 6.5 application. But don't hold me to it. John at quadstar is doing a 6l90 swap and has the converter figured out. He might be able to lead you in the right direction with that.
 

ak diesel driver

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So he's working with a guy from Arizona on this. And one of the things he got from him is basically a gateway module with wiring harness and switches. $875.
 

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FRANKENBURBAN
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So he's working with a guy from Arizona on this. And one of the things he got from him is basically a gateway module with wiring harness and switches. $875.
Thats the pcs 2650. With that he shouldn't need HPTuners as it will take whatever signals you give it and modify them via graphs to whatever you want them to be. You could set it so the TPS is outputting 50%, but make it tell the trans it's 30 or 70%. You can do the same thing with all the inputs from what I found when I looked in to it. And it was the lgh van that got the 6l90 behind the Duramax. The lml was the 397hp truck version, lgh was the detuned commercial version, and it started in 2010 in the vans.
 
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ak diesel driver

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So it turns out that he's swapping the 6l90 for a 6l80. The output shaft is larger and would force him to use the T-case from the dmax, I think he said it was a 261. Also it turns out the guy in AZ is a retired GM engineer and knows his stuff on the 6l80
 

ak diesel driver

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So a small update he was trying to decide whether to go with the spacer kit or the TC. He is going to be getting the TC turns out it already a performance built TC.
 
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