Top end power

[Randomizer]

Just curious, what is the main reason the N54 doesn't make good top end power? I read its because of head flow, they head specifically the exhaust side does not flow very well.
If we theoretically increase flow somehow on an N54 head would we see WHP gains on the stock turbos up top? Not that I am planning to do this I guess im just curious and wondering what people have done to the head of the N54, and if that was tested on the small turbos.

 

[SlowE93]

Turbos is the simple answer

 

[JohnDaviz]

head is very restrictive also. It is basically the whole exhaust side that creates back pressure.
Open up all exhaust related components and you reduce back pressure which means you reduce pumping losses. And then you shift the whole power band to the right because the car looses torque down low.

 

[Montegobluee92]

Came here to say the same thing. The head is super restrictive.

 

[Randomizer]

head is very restrictive also. It is basically the whole exhaust side that creates back pressure.
Open up all exhaust related components and you reduce back pressure which means you reduce pumping losses. And then you shift the whole power band to the right because the car looses torque down low.

Wish it had better top end from factory... Can't have everything I guess.

Comparing to the VQ37 for example, that head flows much better. It has to since its N/A. Though I think I just expected more out of the N54, considering its a 3L TT. the VQ37 can pretty easily hit 330-340whp with a simple intake, exhaust, de cat. Meanwhile the N54 struggles to get past 380whp at 16-18psi on stock turbos, and they fall on their face past 5500rpm, and its unreliable. I guess I just don't see the appeal of the N54?

 

[JohnDaviz]

Actually it can be a very nice fun machine. It just depends on what you really want from a car.

Falling on its face above 5.5k rpm is a stock turbo issue. You can mask the top end topic just by gradually increasing your boost. But then you need everything that supports this strategy.

Or you just port your exhaust ports a little and you transform the character of your n54 engine.

oooor you go full bananas with a complete porting job and bigger valves.

 

[SlowE93]

Yes the head is restrictive, the lack in top end power is still because of the turbos BMW decided to use. BMW was not chasing top end power. What you call restrictive, BMW would call efficient. Their goals and OPs goals are different so different methods will be used.
Is the head restrictive ? Yes , no doubt
Does this actually keep the engine from making top end power ? Fuck no.
99% of people that go single turbo DO NOT do head work and make great top end power. Same for any upgraded twins.

If the head was the main issue for NOT being able to achieve top end power, everyone would be upgrading the head instead of turbos at comparable cost.

Say you have a 6k budget. You can address the MAIN issue for not making top end power.
Do you
A. port the head and increase boost and timing along with FMIC, etc on STOCK turbos
Or
B. Cheapest twins out there with FMIC, etc ?

Which will yield more top end power ?
Not talking longevity (china twins), just top end power as that is the OPs question.

 

[SlowE93]

Falling on its face above 5.5k rpm is a stock turbo issue.

Agreed and said turbos on 1st post
We just had a similar conversation here https://www.spoolstreet.com/threads/what-limits-power-on-n54-with-stock-turbos.9726/


Sup my boy !!

You good John ?

 

[SlowE93]

Wish it had better top end from factory... Can't have everything I guess.

Comparing to the VQ37 for example, that head flows much better. It has to since its N/A. Though I think I just expected more out of the N54, considering its a 3L TT. the VQ37 can pretty easily hit 330-340whp with a simple intake, exhaust, de cat. Meanwhile the N54 struggles to get past 380whp at 16-18psi on stock turbos, and they fall on their face past 5500rpm, and its unreliable. I guess I just don't see the appeal of the N54?

Go get a VQ then instead of asking a bunch of questions about N54s on multiple forums
If you don't see the appeal, why are you here ?
Lets all go on VQ forums and shit on them for making LESS torque from FACTORY on a LARGER displacement engine.
Makes no sense to do so.
Since you want to compare and throw in mods, as you said intake, exhaust, etc, how about you compare what a simple $500.00 on each platform thrown at it yields x amount of power gains.
Pointless comparing N/A vs Boosted IMO but, lets see what you come up with !
Maybe I'll dump my N54 and go VQ 37.

 

[JohnDaviz]

My boy is spitting facts here
What up senior chief vice president associate? You really thrive out there.

Let the boy ask. It is fun for us in the end to see who believes what

I would throw into the ring:
Nobody ports a head with stock turbos buuuuuuuuuut it may not be a really wrong move on a decent twin or single setup.
I think ppl going high power on stock head are usually only going short pulls or not really "racing" like in circuit racing so the engines live relatively long in a time perspective. But i would say all engines at the 700/800+ range die within 10k miles?
A german guy here with 1k hp rebuilds his engine every year (i think he threw the towel some time ago) and we have seen a lot of weird shit on the n54 platform.
I would argue that a little porting here and there with a smart eye on the overall setup would make the engine last way longer in miles than they usually do.

 

[Randomizer]

Go get a VQ then instead of asking a bunch of questions about N54s on multiple forums
If you don't see the appeal, why are you here ?
Lets all go on VQ forums and shit on them for making LESS torque from FACTORY on a LARGER displacement engine.
Makes no sense to do so.
Since you want to compare and throw in mods, as you said intake, exhaust, etc, how about you compare what a simple $500.00 on each platform thrown at it yields x amount of power gains.
Pointless comparing N/A vs Boosted IMO but, lets see what you come up with !
Maybe I'll dump my N54 and go VQ 37.

No need to get all defensive, I'm not trying to stir up drama here. I'm just trying to educate myself and figure out why everyone is drawn to this motor. Personally I think its a fair comparison, they both released around the same time. Imo the N54 doesn't look or feel much like am "M" motor, I'm not saying it has to, as its NOT an M motor... Though when you look at the E46 M3 engine to begin to see similarities with the VQ37, high redline, top end power, N/A. I think my main question is why push an N54 to 700WHP on a stock turbo, when the head flows like garbage (as stated here), and has a bunch of reliablility concerns in general. Having a better flowing head means same power at less PSI, which is better in every way.

Again I'm not attacking this platform at all, I'm looking to get into an N54 powered vehicle actually...

 

[Randomizer]

Yes the head is restrictive, the lack in top end power is still because of the turbos BMW decided to use. BMW was not chasing top end power. What you call restrictive, BMW would call efficient. Their goals and OPs goals are different so different methods will be used.
Is the head restrictive ? Yes , no doubt
Does this actually keep the engine from making top end power ? Fuck no.
99% of people that go single turbo DO NOT do head work and make great top end power. Same for any upgraded twins.

If the head was the main issue for NOT being able to achieve top end power, everyone would be upgrading the head instead of turbos at comparable cost.

Say you have a 6k budget. You can address the MAIN issue for not making top end power.
Do you
A. port the head and increase boost and timing along with FMIC, etc on STOCK turbos
Or
B. Cheapest twins out there with FMIC, etc ?

Which will yield more top end power ?
Not talking longevity (china twins), just top end power as that is the OPs question.

This makes sense and I agree with that, so from what I'm understanding head flow becomes more important past 700-800WHP on a ST setup, as you're already doing all that work.

 

[JohnDaviz]

just to add some facts.

i am working with kmh and not mph but that doesn´t matter.

A stock stage 2+ engine is at what 18psi? it goes 100-200kmh in i think 8 seconds.

My ported engine went 100-200kmh in 8.4s with 9psi.

 

[Randomizer]

My boy is spitting facts here
What up senior chief vice president associate? You really thrive out there.

Let the boy ask. It is fun for us in the end to see who believes what

I would throw into the ring:
Nobody ports a head with stock turbos buuuuuuuuuut it may not be a really wrong move on a decent twin or single setup.
I think ppl going high power on stock head are usually only going short pulls or not really "racing" like in circuit racing so the engines live relatively long in a time perspective. But i would say all engines at the 700/800+ range die within 10k miles?
A german guy here with 1k hp rebuilds his engine every year (i think he threw the towel some time ago) and we have seen a lot of weird shit on the n54 platform.
I would argue that a little porting here and there with a smart eye on the overall setup would make the engine last way longer in miles than they usually do.

Thats interesting insight. For circuit racing it seems that the bottleneck is more so with the cooling setup, even on stock power and hot days the oil and coolant temps overheat. Not that I have any experience with this, just from what I have read.

Now I have to ask, what goes into choosing a motor for a 700/800+ build? If you look at the VQ37 head flow, it flows much better than the N54, which should theoretically allow for easier power. Though that platform has an issue with head lift (that a built motor may or may not solve?) so I guess you just pick the lesser evil lol.

 

[Randomizer]

just to add some facts.

i am working with kmh and not mph but that doesn´t matter.

A stock stage 2+ engine is at what 18psi? it goes 100-200kmh in i think 8 seconds.

My ported engine went 100-200kmh in 8.4s with 9psi.

If this is on stock turbos, then thats pretty impressive, as you're essentially making FBO power at stock boost levels. Which is good for longevity, or you can now turn it back up to 18 psi and run it even faster. Right?

Was there any top end gain after porting on stockers? Or does it still nosedive after 5.5K?

 

[SlowE93]

My boy is spitting facts here
What up senior chief vice president associate? You really thrive out there.

Let the boy ask. It is fun for us in the end to see who believes what

I would throw into the ring:
Nobody ports a head with stock turbos buuuuuuuuuut it may not be a really wrong move on a decent twin or single setup.
I think ppl going high power on stock head are usually only going short pulls or not really "racing" like in circuit racing so the engines live relatively long in a time perspective. But i would say all engines at the 700/800+ range die within 10k miles?
A german guy here with 1k hp rebuilds his engine every year (i think he threw the towel some time ago) and we have seen a lot of weird shit on the n54 platform.
I would argue that a little porting here and there with a smart eye on the overall setup would make the engine last way longer in miles than they usually do.

Lol, and I do agree that racing engines, true racing engines get built over and over in a short amount of time. What most people do for roll racing and things like that is not a true race engine.
Also almost any engine or the vast majority on the planet can benefit from a ported head which is why so many people do this or upgrade the head. But OPs question why the n54 does not have top end Power and the simple answer once again is turbos.

 

[SlowE93]

No need to get all defensive, I'm not trying to stir up drama here. I'm just trying to educate myself and figure out why everyone is drawn to this motor. Personally I think its a fair comparison, they both released around the same time. Imo the N54 doesn't look or feel much like am "M" motor, I'm not saying it has to, as its NOT an M motor... Though when you look at the E46 M3 engine to begin to see similarities with the VQ37, high redline, top end power, N/A. I think my main question is why push an N54 to 700WHP on a stock turbo, when the head flows like garbage (as stated here), and has a bunch of reliablility concerns in general. Having a better flowing head means same power at less PSI, which is better in every way.

Again I'm not attacking this platform at all, I'm looking to get into an N54 powered vehicle actually...

I am not getting defensive because I do not work for BMW nor do I do any research or get paid by BMW. I am simply using what YOU posted.
And as far as your question of why people push 700 whp on the n54 with a stock head just proves my point further of, yes it is restrictive, no it will not stop you from making power. The turbos once again is the main culprit.

 

[Randomizer]

I am not getting defensive because I do not work for BMW nor do I do any research or get paid by BMW. I am simply using what YOU posted.
And as far as your question of why people push 700 whp on the n54 with a stock head just proves my point further of, yes it is restrictive, no it will not stop you from making power. The turbos once again is the main culprit.

Understood, thank you.

 

[SlowE93]

just to add some facts.

i am working with kmh and not mph but that doesn´t matter.

A stock stage 2+ engine is at what 18psi? it goes 100-200kmh in i think 8 seconds.

My ported engine went 100-200kmh in 8.4s with 9psi.

As I said in another post no doubt that porting helps out the vast majority of engines. There is no arguments or denying that. But that is not what limits top end power on a stock N54.

 

[Randomizer]

As I said in another post no doubt that porting helps out the vast majority of engines. There is no arguments or denying that. But that is not what limits top end power on a stock N54.

So that becomes a cost/effort thing then, you could port the head on stock turbos, but its easier and cheaper to just upgrade them.