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Dmac @ BMS/DMD Dmac @ BMS/DMD is offline
Posts: 1,312
Join Date: Aug 2013
Car: 2008 135i
Default 05-03-2015, 12:52 AM

Originally Posted by lcvette
Code DME for manual trans, fabricate Bell housing for 6l90 CTS-V A6, use gm ecm with emulated sensor input and have a proven 800+rwhp paddle shifted A6 designed for a heavier car... With tuning provisions.

Or grab a stand alone tcu TCM-2600 from PCS to control it. Either way this is likely the best solution. Brand new ctsv trans ~$3k would need machined flex plate, 6l90-n54 bell housing (6l90 uses a bolt on bell housing ftw, and the trans body dimensions are similar to the 6hp21 so should fit in tunnel without any fan fare), custom trans mount, drive shaft connection, figure out torque converter (aftermarket is readily available for this). And marry tcm-2600 controller to shifter and paddles. My guess is it would be a bit more than the level 10 after everything is said and done, but you now have full control for shift points and a proven power house of a transmission!

I'm investigating this currently. After I exhausted all other (my opinion) viable options for a reliable 6AT solution, I decided it would be easier not dealing with factory DME. It is too involved and it will take a long time for anyone to crack much less decipher the TCU/DME relationship and then it's going to be trial and error for a year or two before anything is finally sorted well enough to sell. Short of alpina coming out with a high boost upgraded hard parts and clutches flash option, I think this is a long way off.

If you do manage to burn up a 6l80/90, you can grab used ones for under a grand... Makes it worthwhile in my mind.

I wish someone would figure out an answer. Go for it!

After hearing about Terry's fully built transmission refusing to shift I just wanted to clarify something. So there's not any answer (transmission-wise) for a fast high horsepower N54 currently correct? Because no built 6HP21 solution is currently viable past 600whp, the manuals are slow and lose boost on shifts (I've heard NLS is a bad idea from very good sources), and there is currently no other option. So it seems like any N54 past 600 wheel is just a dyno queen and either slow on the street or only holds up for a (relatively) short time.

2008 135i 4L80E Swap - 807 WHP
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