[///Philipp]

I'm planing on getting a custom remap for my 335i.

I read the brochure from ZF which states a max input of 450nm (AT gearbox) but I can se a lot of you guys run with a lot more torque. ZF probably sets specifications below the actual max to be sure everything holds up.

The company recently made this 335i N55 where the max torque in the lower RPM was limited (customer request) to 470nm (347 lb-ft) but they say 550nm will be perfectly fine.

I drive around 16.000 miles a year. Is it nonsense to limit the torque?

[weehe126]

Well how much power do you have? I'd say you only need to worry if you have maxed out a stage 2 turbo or went with a custom single.

[///Philipp]

Originally Posted by weehe126

Well how much power do you have? I'd say you only need to worry if you have maxed out a stage 2 turbo or went with a custom single.

My car is completly stock right now. I have the performance kit though 326ps/450nm.

[weehe126]

Originally Posted by ///Philipp

My car is completly stock right now. I have the performance kit though 326ps/450nm.

Then you have nothing to worry about

[PeterPure]

I run 758nm through my zf 8 speed on a maxed out stage2. Agreed not everyday as with jb4 i can change that around but the gearbox is ok.

I heard the gearbox is ok for 700nm and the torque convertor ok for 650nm. More torque means the torque convertor will wear faster.

[///Philipp]

Originally Posted by Darkhold

I run 758nm through my zf 8 speed on a maxed out stage2. Agreed not everyday as with jb4 i can change that around but the gearbox is ok.

I heard the gearbox is ok for 700nm and the torque convertor ok for 650nm. More torque means the torque convertor will wear faster.

The N55 probably won't make more than 550nm without any other modifications. Probably nothing to worry about then.

[Ozzie335i]

Is there a different formula for deriving Hk than hp? Asking since with hp the crossover is at 5252.

[///Philipp]

HK is the same as HP, HK is just ist an abbreviation for the Danish word for horsepower.

On the car above the torque was limited to 470nm which will affect the crossover.

[PeterPure]

Originally Posted by ///Philipp

HK is the same as HP, HK is just ist an abbreviation for the Danish word for horsepower.

On the car above the torque was limited to 470nm which will affect the crossover.

Actually that has nothing to do with your crossover.

Its at different rpm for 2 reasons:
- nm crosses at different rpm than torque
- your scale left and right for hp and torque are different

[YouAreMyWorld]

Correct me if I'm wrong, but I don't think it's necessarily a matter of outright limiting the torque, but rather when the output of said torque will come available.

Having heaps of torque rush in early I think is where most people run into issues (most especially in XI's); having a more linear torque curve or moving the majority of the torque higher in the RPM I personally feel will yield far greater results not just in terms of reliability but overall drivability.

Again what I'm saying may not necessarily be factual, but from what I've browsed throughout the forums, for our vehicles specifically (AT), it seems as if the correct route for those running non-stock snails should have torque limited, at least somewhat, early on in the RPM band.

If you're on stock snails, even when pushing them to the max, I haven't personally read any disconcerting information in regards to torque-converter issues, so you needn't worry.

That's just my $0.02 though.

[snaimpally]

Why not buy a Prius? That will limit your torque.

You could buy a Cobb AP and load the valet map.

[///Philipp]

Originally Posted by snaimpally

Why not buy a Prius? That will limit your torque.

You could buy a Cobb AP and load the valet map.

My wife has a VW Up! with 95nm

What is our 335i producing with a stage 1 turbo?

[Unklejoe]

Originally Posted by YouAreMyWorld

Correct me if I'm wrong, but I don't think it's necessarily a matter of outright limiting the torque, but rather when the output of said torque will come available.

Having heaps of torque rush in early I think is where most people run into issues (most especially in XI's); having a more linear torque curve or moving the majority of the torque higher in the RPM I personally feel will yield far greater results not just in terms of reliability but overall drivability.

Again what I'm saying may not necessarily be factual, but from what I've browsed throughout the forums, for our vehicles specifically (AT), it seems as if the correct route for those running non-stock snails should have torque limited, at least somewhat, early on in the RPM band.

If you're on stock snails, even when pushing them to the max, I haven't personally read any disconcerting information in regards to torque-converter issues, so you needn't worry.

That's just my $0.02 though.

You're close, but not exactly right. You seem to be confusing the relationship between torque/horsepower with the relationship between RPM/torque.

If we're talking about stress on the transmission, when the torque comes (in terms of "what RPM") does not really matter. All that matters is the absolute (instantaneous) torque that the transmission is experiencing.

However, if we are talking about "what horsepower will make the transmission break", then the torque/RPM relationship matters. A small turbo car like ours will achieve 400HP by making a ton of torque at a lower RPM than something like a Honda.

Example:

Assume you have a hypothecial 335i making 400HP at 3800RPM. That means that at 3800RPM, it must be making 552 ft*lbs of torque.

Now assume you have a turbo Honda making 400HP at 8000RPM. That same car would only be producing 262 ft*lbs of torque.

The 335i in this example will be stressing its drivetrain a lot more than the Honda.

This is why a bigger turbo can actually be safer for some motors. It moves the torque curve to the right which makes more horsepower without really stressing the motor any more.