N52 rev limit

[sclass]

Wsup everyone,

Just wondering if anyone can conclusively state whether there is NO PHYSICAL reason the N52B25 in the 323i cannot rev to the 7000 rpm of the 325i, seeing as they are "supposedly" identical? Is the difference purely that of software and intake?

On a side note, 323i should've come with a sportier diff ratio than the 325/330 to compensate for the fewer horses and lower rpm limit...

Cheers :thumbs:

 

[Philip Foglar]

Mechanically the engine is the same as far as I know, it is just the intake runner and the software that makes the 323i different to the 325i. Overseas they have the 3.0i 325i engines, so they are just intake and software away from being a 330i... There are tons of threads on E90Post about these conversions! :thumbs:

 

[sclass]

Thanks Phillip

The overseas discussions aren't conclusive either, and the topic gets muckier because our version of the 323i was only available in Canada and Malaysia/Singapore, and the 325i to 330i discussions are based on the N52B30 (we only got that in the E92 325i). I did see a youtube clip though of a 323i on a dyno revving to 7k when a lot of the guys were saying it can't be done. So I was kind of hoping someone locally had an answer.

:thumbs:

 

[Philip Foglar]

Thanks Phillip

The overseas discussions aren't conclusive either, and the topic gets muckier because our version of the 323i was only available in Canada and Malaysia/Singapore, and the 325i to 330i discussions are based on the N52B30 (we only got that in the E92 325i). I did see a youtube clip though of a 323i on a dyno revving to 7k when a lot of the guys were saying it can't be done. So I was kind of hoping someone locally had an answer.

:thumbs:

Was it not the 125i that used the detuned N52B30 motor?

What are the exact differences between the local 323i and 325i, that's going to be the best way to know.

Hope you can find some more answers. :thumbs:

 

[moranor@axis]

It might not make power at higher RPM but I dont think there is any other reason you cant do it

 

[sclass]

Actually you're right about the 125i. Not so sure about the E92 now

At the very least we know the 323i doesn't have the 3 stage intake of the bigger boys, and it has a different tune. Maybe zorst is more restrictive too. But you wouldn't want to free up that extra 500 rpm only for the valvetrain to pop because the 323 isn't running the same special materials (eg. springs,valve stems etc) of the 325!

@Moranor to be honest the motor is at it's best at high rpm and really hauls from 5000 to the cut out with no drop off (like an M52), so it makes you wonder

 

[Philip Foglar]

Actually you're right about the 125i. Not so sure about the E92 now

At the very least we know the 323i doesn't have the 3 stage intake of the bigger boys, and it has a different tune. Maybe zorst is more restrictive too. But you wouldn't want to free up that extra 500 rpm only for the valvetrain to pop because the 323 isn't running the same special materials (eg. springs,valve stems etc) of the 325!

@Moranor to be honest the motor is at it's best at high rpm and really hauls from 5000 to the cut out with no drop off (like an M52), so it makes you wonder

Was going to say, forgot to mention the exhaust system of course. But yes, 323i I gather just has a normal intake (no DISA flaps at all), where the 325i has the two stage intake with one DISA flap. Does your 323i at least have the big Euro intake like the 325i and 330i? The US guys have some puny restrictive carbon filter emissions intake system, and one of the first mods is to ditch this for the Euro type intake and air cleaner etc.

 

[sclass]

Hmmmmm interesting, I did not know about this Euro intake....! I'm sure the costs (and complexities) of doing these swaps mean it isn't worthwhile though ...the easy way is the BMS powerbox + decat + zorst + NOT fitting 19s....or just getting a 330 to begin with!

This is all quite interesting though

 

[moranor@axis]

Rev limit it probably the product of marketing... lower insurance and emissions play a big part

cross reference part numbers on realoem with the 2.5l 325i I will not be surprised if everything in the head is the same... using the same parts bring cost down dramatically for BMW

 

[Philip Foglar]

Hmmmmm interesting, I did not know about this Euro intake....! I'm sure the costs (and complexities) of doing these swaps mean it isn't worthwhile though ...the easy way is the BMS powerbox + decat + zorst + NOT fitting 19s....or just getting a 330 to begin with!

This is all quite interesting though

I fully agree with Moranor! Chances are, most parts are exactly the same, but best to cross reference to be sure.

As for the Euro intake, this is what it looks like:

:thumbs:

 

[sclass]

Hmmmmm interesting, I did not know about this Euro intake....! I'm sure the costs (and complexities) of doing these swaps mean it isn't worthwhile though ...the easy way is the BMS powerbox + decat + zorst + NOT fitting 19s....or just getting a 330 to begin with!

This is all quite interesting though

I fully agree with Moranor! Chances are, most parts are exactly the same, but best to cross reference to be sure.

As for the Euro intake, this is what it looks like:

:thumbs:

That's the intake that I have. Maybe the 130kw version had a smaller intake?

 

[sash]

I think Yulz had done this conversion on his 323i, pm him for more info