Interesting facts on changes made to the M235i

[ShaunJeremy]

Came across some interesting read...

BMW M235i is Faster On Track Than 1M Coupe (Our 2 Series Interview From Detroit)

2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning New F-Series Downpipe for the M235! BMW Changes design as of 07/13 Build!

So in summary:

- 4" dp (so with the new N55 models in the new batch)
- Software update, improved cooling system
- Cast iron camshaft was replaced with a steel version
- a more aggressive tune to the exhaust

 

[ShaunJeremy]

Re: Interesting facts on changes made to the M235i

Still cant find anything on whether M had tweaked the GA8HP45Z Zf gearbox that is installed into the Mx35i models.
No logic that they overengineer-ed the engine but installed a gearbox w torque limits that's equal to the stock tune.

 

[Cateye]

Re: Interesting facts on changes made to the M235i

I read somewhere in bimmerpost that there was an interview done once with the representative of gearbox manufacturer. He mention that the GA8HP45Z could take up to 600nm. Well dun take my words for it.
I have been monitoring if there is any issue with the gb on the forums. Seems that all good.

On M235, that explains the output to 322hp (bigger dp, with better cooling and different tune) as M135 stands at 320hp

Cheers

 

[ShaunJeremy]

Re: Interesting facts on changes made to the M235i

I read somewhere in bimmerpost that there was an interview done once with the representative of gearbox manufacturer. He mention that the GA8HP45Z could take up to 600nm. Well dun take my words for it.
I have been monitoring if there is any issue with the gb on the forums. Seems that all good.

On M235, that explains the output to 322hp (bigger dp, with better cooling and different tune) as M135 stands at 320hp

Cheers

I think essentially the same la. too little of an increase to count for an improvement . perhaps the only thing that is good is better handling cos diff wheelbase.

I been checking bimmerpost and all other forums as well... most are opinions made by either pro tuners whom have R&D or had experience tuning rides with zf gearboxes. There's also that zf representative who commented as well...

But no official reports but i reckon if somebody really badly needs a tune, an increase of 50nm torque would still be within the safe boundaries ba. (just my layman 2 cents! )

 

[Red_Bean_Bun]

Re: Interesting facts on changes made to the M235i

I NTC2 only so maybe other real expert can say something ......

The maximum permissible torque is the maximum moment exerted on the final drive.

If you think about the gear ratios - you need 2 numbers. In this case, input torque and output torque.

If 450nm is the maximum amount of torque for the input torque of an auto trans (post torque converter) then it may make sense because the final drive ratio is usually between 3 to 4. Other gears usually lower than that by a lot. Then the maximum output torque would be a multiple of the input torque courtesy of the rear differentials.

Then torque higher than the max permissible torque can be produced at the rear wheels to move the car. Thus when dyno - it is measuring NM to the wheels (post rear diffs).

Unlikely input torque would be operating at max all the time ...... Like just a fraction of that.

My 2 cents ........ And this was a mod last time when my ride got no turbo ..... Change rear diffs to change final drive ratio to get more pickup .....