OEM-level 8HP swaps in E-series cars

Svmp

Specialist
Dec 23, 2019
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M50 DCT & M57 DCT
Thought i'd share some info on what's possible nowadays with these transmissions.
I've been driving around for over 6 months now with my 8HP-swapped daily E91 using my own controller (CANTCU), constantly doing R&D and developing further, and now it's pretty much finished regarding E6x/7x/8x/9x integration.

This is the only existing solution that keeps the OEM TCU inside the transmission, making it possible to install without disassembling/soldering etc, doesn't need any tuning, and works silky smooth like OEM. Simply put, it makes the car and the 8HP understand each other.

At the moment there are some beta testers driving around in various cars/engines like N54/M57/N57. Here's a video example of a fast diesel (E92 330xd N57) with an 8HP70X transmission (fully stock trans in the video, it got xHP afterwards).


The nice thing about E-series xdrive-cars is that the transfer case from a manual/6HP fits directly onto a xdrive-model 8HP transmission, so it will also work directly without any extra modifications.

To keep this post more informative than just a crude advert, i want to mention that there also are other solutions available to control the 8HP, in which the OEM TCU is removed and replaced with an aftermarket unit that fully controls the transmission instead, those solutions are TurboLamik and HTG.
 
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johnnyd40

New Member
Jun 21, 2022
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looks awesome, I read somewhere that the front diff is a weak point, is this true? I would suspect the transfer cases to be a weak point
 
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Svmp

Specialist
Dec 23, 2019
53
59
0
Ride
M50 DCT & M57 DCT
looks awesome, I read somewhere that the front diff is a weak point, is this true? I would suspect the transfer cases to be a weak point
Well, surely both the transfer case and front diff will at some point be weak points. But i haven't really investigated it as i don't have an xdrive-car myself.

Do you include a adapter plate?
Nope, we concentrate on controlling things. There are a ton of vendors supplying mechanical adapter plates etc for conversions like these. Places like PMC Motorsport, DomiWorks etc. Also, an adapter isn't even needed if you use a 8HP45 from a N55.
 
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MR-KRAKA

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May 23, 2020
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I was trying to hold off on making a post on this until after I got to the track but... I’ve been running the CANTCU for about a month now E90/N54/xDrive 8HP45X (first ever?) I am impressed with how far the software has come in just the short time and how fast Ken was able to implement various fixes (and improvements) throughout the Beta. There was plenty of bugs to work out in the beginning mostly Gas vs Diesel issues and I know I was the Bane of Ken’s existence for a while but it all paid off in the end. The Software is very polished now and he’s still pumping out the updates. While I am still working on the DME tune (IJE0S xDrive life) side of things as time allows, I can say this implementation is as close to oem as you’re going to get for this type of swap. By far best “mod” I’ve done so far besides upgraded turbos. Second gear gets placed in a very nice ratio between the 6hp’s 1st/2nd for launch and just DD duties in general. There is also maybe a little placebo effect going on banging through all the gears so quickly when you’re used to the long 6HP. It definitely livens things up a little more.

I opted to try this unit over the others for a few reasons. First I couldn’t find one example of the other options out there having functional xDrive outside of a reply to a YouTube comment saying it would be possible. Secondly you are using the oem TCU in this case programmed by ZF and combining that with XHP which I feel has proven to be quite reliable over the years. There has been far more testing than all the others out there with this combo. Direct control of solenoids/full standalone I’m sure has its advantages over this at racecar level but for me I wanted to be able to hand the keys to my wife without worries or her telling me somethings not right. Another factor was the language barrier vs the others. While Ken is based out of Finland he spoke perfect English and was not an issue at all even with al the technical speak. Time difference was the only thing that got in the way sometimes but I’m not sure if the guy sleeps anyways? None of that should matter now since the unit is plug and play past initial setup, this was all during testing.

For the physical swap itself the only modification required is adapting of the smaller 6HP oil cooler lines to the larger ports of the 8HP45. There’s several offerings out there like th adapter plates take your pick. And for the exhaust mount to the transfer case I had to find just the right length bolt/bushing washer/combo to make the stock bracket work because the pan seems to sit a little further back than the 6hp. Otherwise a direct swap. This applies when converting from 6HP19/21 to 8HP45X from an N55 powered F10 in my case. 8HP70 will require an adapter plate setup and I may regret not taking that path once I really start pushing it but time will tell. So far holding up ok in the 550-600whp range for me. I was concerned about the additional length with xDrive being uncharted territory. I didn’t have one to compare but if it were to add even a few mm To the overall package I suspect I would be needing a custom driveshaft at the very least. The 8HP45 is largely the same trans used on the B58 powered stuff now and they seem to be doing ok at least up to my power goals currently. These trans are cheap and readily available if you shop around but I definitely do not want to have to do this swap again anytime soon at least without a lift…

Next up I will hopefully get back to the drag strip soon, maybe tomorrow to see what kind of net ET gain there is at the same power level as last year. I suspect it should be significant from my 60ft alone. Here’s just a short video I made for internet proofz please don’t make fun of my skills lol

I’d be happy to answer any questions on the swap. This is not a paid promotion, no one put me up to this. Just a happy PITA customer 😁
 
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