Nizpro 6HP21 Upgrade?


Oct 18, 2016
Over onthe Nizpro blog Simon has left a lengthy update in May on where they are at with their 6HP21 upgrade:

The BMW community are well aware that the transmission fitted to their 335 N54 powered vehicles is the smaller cousin to what is used in the Ford Falcon XR6 turbo range. We have been able to achieve amazing results from the ZF 6HP26, it is now capable of handling well over 1200 engine horse power with our latest hardware and software upgrades.

Unfortunately the BMW guys have not had the luxury of ongoing development to their ZF 6HP21’s. Suffering all the issues experienced by Turbo Ford Falcon owners back in 2006-2008 before Nizpro started development of what has now been proven as a fantastic transmission for high performance upgraded cars.

That being said, no matter what power levels have been achieved with the mighty twin turbo 3 litre BMW engine, acceleration times have always been off the pace for the given power and weight of the vehicles. There have been endless complaints by owners suffering with slipping transmissions and long gear changes, hence slow quarter mile times.

With our reputation growing due to the achievements of customers running Nizpro upgraded ZF transmissions, it was only a matter of time before we were asked to develop an upgrade package for the smaller 6HP21 for BMW owners.

Due to an already heavy workload, and a project that snowballed in size, it’s been nearly 2 years since we initially undertook the 6HP21 development. Most of the development for the 6HP21 was simply carried over from the 6HP26, but still required all our tooling and jigs to be reproduced due to the different size of all the components. On an upside for 6HP26 owners, some extra developments needed for a successful 6HP21 were now carried back to 6HP26.

After 8 years experience with the 6HP26, the mechanical upgrades needed for the 6HP21 were not groundbreaking as far as we were concerned, however a massive problem was the transmission software calibration, or lack of to be precise.

Transmission power handling capabilities and performance can be divided into two almost equally important categories:

  1. The upgrading of internals to allow for extra torque requirements.
  2. The software calibrations allowing for adjustment of torque management, shift speeds and transmission pressures.
One without the other gives a 50% result at best.

Now, many said re-calibrating the ZF via the BMW OBD2 port along with locating the calibration tables required for transmission control could not be possible. We at Nizpro are very excited to say that we have now been able to achieve this goal. It is now possible to read existing calibration, and also write new calibrations. New calibrations can be flashed directly to the ZF TCU via the OBD2 port.

The next development period will see us concentrating on custom calibration for use with both the standard ZF 6-HP21, and our upgraded transmissions. We will have hardware and software calibrations that can be purchased directly from us, and then loaded into the vehicle by their owners.

So what does this mean regarding performance gains for N54 owners?

Here’s the bit that most of you will love, these are real world measurements of transmission improvement:

  • As a proven example, one of our Level 2 internally upgraded 6HP26 transmissions using standard calibration will be 2 tenths faster over the ¼ mile compared to a good condition standard transmission.
  • Take the same Level 2 upgraded 6HP26, add a recalibrated file and you will see a further reductions of 4 tenths.
  • Now, if you were to put the same recalibrated file into the stock transmission the input shaft would likely fail before the end of the first pass.
These numbers are based off proven results on a flat 10 second 4200 lbs vehicle. To be clear, the recalibrated and upgraded transmission will take a flat 10 second time slip down to 9:40 or better. After purchasing our own test BMW 335I, and performing mild upgrades to lift power to 300 rwkws, we see that the standard shift speeds are far slower than any standard Ford XR6 Turbo fitted with a ZF transmission running a standard calibration. I would say that the improvements of the BMW will prove greater than the above examples.

I look forward to providing more information and results as they come to hand.

Regards Simon
Here is a video of their shop car with billet input and intermediate shafts with billet basket and custom Nizpro frictions with NO software:

We will have to ask @[email protected] about the status, but apparently they have one of the Nizpro transmissions installed and were waiting for the Nizpro technician to come test drive it and make sure it is operating properly.

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The question I have is, this transmission that you guys have, does it have their software tune on it? Or still just the hardware upgrade alone?
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Reactions: Sean Webster


Nov 6, 2016
Looks like this is the end, Nizpro is selling their car:

It sounds like they don't have a partner like EuroTrans to program the software the way they need like Propulsive Dynamics has?
Correct. There are very few shops that will invest in the machines needed to do what ET does. Being that they are a certified OEM transmission refurbishment facility for BMWNA, they are required to have this capability. The key is being able to adequately calibrate the TCU to the new internal hardware, which they do in the loaded transmission dyno cell.
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