[porsche959]

whats the highest redline you have seen or are running on an n52 with a tune?

possible to get it up to 8k?

i get the powerband flattens out, but a screaming 8k redline on a retrofit m3 gauge would be sweet if it didn't blow anything up

[Biginboca]

I watched an interview with Steve Dinan where he said his personal rule was “Do not exceed 4500 ft/min piston velocity” because it wears the rings.

The 3.0 litre models of the N52 have a bore of 85 mm (3.3 in), a stroke of 88 mm (3.5 in) and a compression ratio of 10.7.

When I did the math 4500ft/min was around 7700-7800rpms and I have mine set at 7500.

BPC ran one to 8200 on their dyno a bunch of times but they also blew one up just to see the limits. I don’t want to see the limits on mine lol

[Taskmaster]

7500RPM seems to be the safe point, and is also about the same as the S55 (with a similar valvetrain)

The problem is actually making enough power that high up to use it.

[hassmaschine]

Going past 7000rpm with a 3 stage is pointless - the negative resonance after that point causes torque to drop quickly. If you have a different manifold setup (not the single stage, lol) - then more could be done at higher RPM. I have mine set at 7500 but it's more so I don't have to shift in the middle of a curve.

[Dsycks]

According to gear and application there will be times that going a bit past the ideal rpm for power will be in ones best interest.

For me, I hope to be able to get a little above 7k so we don't end up rev limited in some areas of certain tracks (endurance racing) but also don't want to push the engine to places where its unhappy or puts longevity at risk (ENDURANCE racing).

[W37V]

Originally Posted by porsche959

possible to get it up to 8k?

Yes

Originally Posted by porsche959

whats the highest redline you have seen or are running on an n52 with a tune?

Technically, 8200 rpm

Originally Posted by porsche959

i get the powerband flattens out, but a screaming 8k redline on a retrofit m3 gauge would be sweet if it didn't blow anything up

You might experience valve float. Like others said. No point going that high.

[desertman123]

let's say we have an N54 intake manifold and MILVS, whats the new limiting factor for flowing air?

[Taskmaster]

Originally Posted by desertman123

let's say we have an N54 intake manifold and MILVS, whats the new limiting factor for flowing air?

Cams.
Valvetrain.

7500 seems to be a good spot.

[Kubricks]

Reviving the thread here.
I just wanted to ask how's everyone with their N52 which has a raised redline holding up?

Right now my N52 supercharged engine has a torque dip at 4600rpm due to the way supercharger/vanos works and is unable to tune out. This become a problem when I shift from 2nd redline to 3rd where rpm will land at 4500~4600rpm.

I am thinking of raising the redline to 7500rpm to counter the problem, which will theoretically put me at 5000rpm on 3rd which is much better according to my dyno plot. Any thought?

[Biginboca]

Originally Posted by Kubricks

Reviving the thread here.
I just wanted to ask how's everyone with their N52 which has a raised redline holding up?

Right now my N52 supercharged engine has a torque dip at 4600rpm due to the way supercharger/vanos works and is unable to tune out. This become a problem when I shift from 2nd redline to 3rd where rpm will land at 4500~4600rpm.

I am thinking of raising the redline to 7500rpm to counter the problem, which will theoretically put me at 5000rpm on 3rd which is much better according to my dyno plot. Any thought?

I think it’s a good idea. Noir is running a S/C and a 7500 rpms redline so it will be good to get his thoughts.

Any chance you can post that dyno plot?

[Kubricks]

As above. Landing at 5000rpm would be much better.
Forget about the number they are all relative, the curve is the story here.

[Biginboca]

Originally Posted by Kubricks

As above. Landing at 5000rpm would be much better.
Forget about the number they are all relative, the curve is the story here.

What intake manifold are you running? Are you running secondary cats, catless headers, etc?

[Kubricks]

Originally Posted by Biginboca

What intake manifold are you running? Are you running secondary cats, catless headers, etc?

It's a stock euro spec e87 130i manual.
It comes with 3 stage IM and no secondary cat. The header is stock.

[W37V]

Originally Posted by Kubricks

Reviving the thread here.
I just wanted to ask how's everyone with their N52 which has a raised redline holding up?

Right now my N52 supercharged engine has a torque dip at 4600rpm due to the way supercharger/vanos works and is unable to tune out. This become a problem when I shift from 2nd redline to 3rd where rpm will land at 4500~4600rpm.

I am thinking of raising the redline to 7500rpm to counter the problem, which will theoretically put me at 5000rpm on 3rd which is much better according to my dyno plot. Any thought?

There was an extensive debate about supercharger and redlines and what would need to happen (bigger / smaller pulley to take advantage of the redline and power curve. etc).
I think in your case, you might want consider higher rear differential which would help you achieve the same result (putting you in higher rpm).

[Noir]

I will post a video later on..
I guess it kinda evens out around there for me
Still the typical die off at the very top end.
I am running open headers though

[Kubricks]

Originally Posted by W37V

There was an extensive debate about supercharger and redlines and what would need to happen (bigger / smaller pulley to take advantage of the redline and power curve. etc).
I think in your case, you might want consider higher rear differential which would help you achieve the same result (putting you in higher rpm).

I have thought of higher final gear as well but after my experience with previous cars, including a Toyota Altezza (4.1 to 4.7 final gear) and Honda S2000 (4.1 to 4.444 final gear), let's just say I don't want to do this. I know we will be operating in higher rpm most of the time with a higher gear ratio, but it also reduce each gear's range at the same time, meaning more gear shift and more chances to run into redline which is something I hate.

Smaller pulley would improve things but the effectiveness at mid-range is limited due to how SC works (higher the rpm higher the boost). Higher redline seems like a more direct solution.

Then again I have no idea how much longevity I am sacrificing with the additional 500rpm. I know BPC ran it to 8200rpm but that can hardly be used as reference for a DD like mine.

[Kubricks]

Originally Posted by Noir

I will post a video later on..
I guess it kinda evens out around there for me
Still the typical die off at the very top end.
I am running open headers though

Hey I didn't know you have your redline raised, how does the engine feel?

[Noir]

Originally Posted by Kubricks

Hey I didn't know you have your redline raised, how does the engine feel?

Yes sir!
it's cool and all, but I still have that drop off around what was it. 6500 6800? Looking to swap to the n54 IM and my 3.91 diff is on its way to synchrotech. Hopefully it'll feel uber better

[rjahl]

Originally Posted by Noir

Yes sir!
it's cool and all, but I still have that drop off around what was it. 6500 6800? Looking to swap to the n54 IM and my 3.91 diff is on its way to synchrotech. Hopefully it'll feel uber better

Has anyone logged their actual boost pressure through the RPMs?

[Noir]

not I

[dwashy]

7500 RPM redline has been treating me fine. There is that 3IM dip at 6800 which sucks though, but on the shift from 7500 you're higher in the rev-range so it pulls well after the transition to the next gear. Had that redline set at 7500 for maybe 5-6 months, and only give her the beans when she's warm of course. No issues here

[Bob@BPC]

Originally Posted by rjahl

Has anyone logged their actual boost pressure through the RPMs?

I have. This was a car with the ess "upgraded" injectors and they were maxed out at this power level. Since its a centrifugal supercharger it relies on rpm for boost. The more rpm you give it, the higher the boost level gets.