[kazkas3000]

Hello, I have 325d(m57n2) pre-lci with automatic transmision(6hp21), and I would like to ask whats the highest torque anyone has tried on this engine and this transmission, without any problems?

Mine currenlty has around 480-500nm, and I haven't had any problems yet, but I would like to try and push it to 550-600nm.

I know the engine can hold way more torque, but I'm not sure about the trans since it's upgraded trans from 320d.

[ValSolo]

6hp21 is rated at 450Nm

[kazkas3000]

Originally Posted by ValSolo

6hp21 is rated at 450Nm

335i useses the same gearbox, and some people are pushing way over 600nm on it. Torque curve is a bit different, maybe that helps.

[therealdb1]

Ah the proverbial piece of string question!
The gearbox is rated at 450 Nm.
The 335i output I believe is 400 Nm so the transmission has safety headroom.
You can push the transmission as far as you like and eventually you are likely to break it because it isn't designed to withstand more 450 Nm plus tolerances.
It is all very well saying some people are tuning their engines to produce 600 Nm of torque but are they actually using that capabilty? I suspect beyond a dyno session for bragging rights they probably don't which is why they haven't yet destroyed their transmission!

[rasa bmw]

my old e92 335d had 739 nm,and my 640d over 800 nm,,it all depemds how it's driven,,if ya launching it hard often then it's going to shorten its life,,it's why i get gearbox serviced every car ive bought with auto box,,,just because my car had 730 nm dont mean its pushing 730 nm all the time or even never,its how you use the gas pedal

[therealdb1]

Originally Posted by rasa bmw

just because my car had 730 nm dont mean its pushing 730 nm all the time or even never,its how you use the gas pedal

Precisely my point. Just because it is there doesn't mean you are using it very often.

[kazkas3000]

Originally Posted by rasa bmw

my old e92 335d had 739 nm,and my 640d over 800 nm,,it all depemds how it's driven,,if ya launching it hard often then it's going to shorten its life,,it's why i get gearbox serviced every car ive bought with auto box,,,just because my car had 730 nm dont mean its pushing 730 nm all the time or even never,its how you use the gas pedal

335d box can hold 750nm, so you were safe there ;D I'm thinking about getting 6hp28 gearbox before I try to max out my current one. I just don't know if it will be PnP or I will need to do something else. I don't like doing launches from stop, I'm more of a rolling start guy, so maybe my current one will hold just fine.