[B58]

Originally Posted by GT500R

Can the ZF handle that much torque? It sounds super high based on what the ZF can handle.

Keep in mind the new M5 uses our transmission so it's capable of handling all that torque, but we may have some sort of torque limits set from the factory that can be removed from a transmission flash. I spoke to Alex a while back and it seems like hes in the market to only sell his transmission flash if you're planning on running one of his ecu software. We might not even need a flash only time will tell when these boring beta days are over.

[GT500R]

Originally Posted by B58

Keep in mind the new M5 uses our transmission so it's capable of handling all that torque, but we may have some sort of torque limits set from the factory that can be removed from a transmission flash. I spoke to Alex a while back and it seems like hes in the market to only sell his transmission flash if you're planning on running one of his ecu software. We might not even need a flash only time will tell when these boring beta days are over.

M5 uses 8HP50? Thats only 500 ft lbs of torque and M5 has more then that stock.

https://en.m.wikipedia.org/wiki/ZF_8HP_transmission

Edit - M5 uses 8HP75, not same transmission.

[TBONE1969]

I believe it uses the 8HP75, which is rated to 750Nm.

[hybris]

Originally Posted by GT500R

M5 uses 8HP50? Thats only 500 ft lbs of torque and M5 has more then that stock.

https://en.m.wikipedia.org/wiki/ZF_8HP_transmission

Edit - M5 uses 8HP75, not same transmission.

8HP50 is rated to 500nm, so around 370 ft lbs.

[GT500R]

Originally Posted by hybris

8HP50 is rated to 500nm, so around 370 ft lbs.

Yes thank you. I’m already over 400 with the trans tune so how far should one really go based on the dyno above?

[hybris]

Originally Posted by GT500R

Yes thank you. I’m already over 400 with the trans tune so how far should one really go based on the dyno above?

Hard to say. I talked to a local tuner friendly and official ZF service shop when I was already slightly over 500nm, and he said I had nothing to worry about, so the stock rating is clearly conservative. He did however advice me to service it at 60.000km.

People are running way beyond that too without the gearbox exploding, but hard to know how long it will last. But in general my impression is that the ZF is very durable and people are running them way past their rated limit.

To take my implementation as an example (330e), the stock torque is 420nm, and the torque limiter is at 550nm. So I guess that in itself is an interesting fact. The stock torque limiter is actually 10% higher than the rating of the gearbox. So they're probably pretty confident it can take at least that much.

[B58togo]

Originally Posted by hybris

8HP50 is rated to 500nm, so around 370 ft lbs.

Damn, so only 1 ft lb more than an M240i makes when stock. Seems odd.

[hybris]

Originally Posted by B58togo

Damn, so only 1 ft lb more than an M240i makes when stock. Seems odd.

It's right there in the wikipedia link posted above. And it's correct.

EDIT: To make it easy for you, that's actually what the 50 stands for

8HP45 (previous generation) had 450nm, the 50 has 500nm, the 8HP75 is 750nm, etc.

[B58togo]

Yes, I've seen the Wiki page. But regardless, that doesn't make it any less odd that the transmission is rated for the exact output of one of the cars it's used in (actually a fraction of a ft lb less, if we're splitting hairs). 500 NM = 368.78 ft lbs. I'll have to assume the ratings are very conservative.

[G.Newt]

Originally Posted by hybris

It's right there in the wikipedia link posted above. And it's correct.

EDIT: To make it easy for you, that's actually what the 50 stands for

8HP45 (previous generation) had 450nm, the 50 has 500nm, the 8HP75 is 750nm, etc.

I don't think he's questioning the facts, so no need to keep validating and re-explaining.

Rather, the "seems odd" purports that either BMW thinks it's okay to run it right on the ragged edge of its rating (of course this is wrong lol), or the ZF8 can take WAAAAY more torque than it's rated for. <- That's probably our winner lol.
We can probably assume some 10-20%+ headroom. So a stage 1 or even stage 2 tune should be fine for the stock trans. Hell, the manual is rated even lower and people have been pushing 600+ from N54 days (they have the same 6MT).

[F3085258]

Originally Posted by fuseryder

end of the month

Thanks. That’s not too long to wait. 🤞

[B58]

Which is why a trans flash will remove the stock torque limits and raise it.
We’ll just all have to wait and see

[MTWO]

Does anyone know what MAP sensors are on the B58 stock? Does it come with 2.5bar or 3.5bar from the factory?

[MassNerd]

Originally Posted by B58

Which is why a trans flash will remove the stock torque limits and raise it.
We’ll just all have to wait and see

So I'm new to this transmission tuning thing (and new to BMWs). How is transmission software related to torque limits?

Intuitively that doesn't make sense to me unless the transmission is purposely slipping clutches above its programmed limit.

I could understand an ECU flash changing the torque. Help me understand!

[jrdoming]

Originally Posted by MassNerd

So I'm new to this transmission tuning thing (and new to BMWs). How is transmission software related to torque limits?

Intuitively that doesn't make sense to me unless the transmission is purposely slipping clutches above its programmed limit.

I could understand an ECU flash changing the torque. Help me understand!

The way I understand it is the TCU has max torque limits in some gears that sends messages back to the ECU that cause an intervention (cutting fuel etc). Tuning helps to relax those a bit as well as smooth out other things related to the additional torque and HP being put through the transmission.

[kern417]

Originally Posted by MTWO

Does anyone know what MAP sensors are on the B58 stock? Does it come with 2.5bar or 3.5bar from the factory?

The part number is 13628637896 but I can't find a rating anywhere. With our stock boost levels, idk why BMW would fit one larger than 2.5 bar. That would still support 21-22psi

[j1980mac]

Wow, anyone see this? Full E85 (map) X3 M40i no bolt ons:

0-60 = 3.8 sec
1/4 mile = 12.1 sec at 111 mph.

[B58togo]

^^

I saw that yesterday. Looks like Paul is tuning the wife’s grocery getter.

[GT500R]

That’s pretty good for no bolt ons.

Here is mine with no bolt ons and on E30.. and letting off at the end.

[j1980mac]

Originally Posted by GT500R

That's pretty good for no bolt ons.

Here is mine with no bolt ons and on E30.. and letting off at the end.

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View post on imgur.com

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You're an X3 M40i on the MP ECU Stage 2 with the TCU Stage 1, right?

[GT500R]

Originally Posted by j1980mac

You're an X3 M40i on the MP ECU Stage 2 with the TCU Stage 1, right?

Correct, tune only. I wish I had a full E85 tune to run, maybe Alex is looking for those fuel maps as we speak

[j1980mac]

Originally Posted by GT500R

Correct, tune only. I wish I had a full E85 tune to run, maybe Alex is looking for those fuel maps as we speak

You should ask him about it.