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Rb 25det Rev Limiter

Branelly

By Branelly,
in Engines & Forced Induction

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Branelly Enthusiast

Branelly

Posted
Posted

So my cars going in on wednesday to get a z32 ecu and nistune installed and tuned up. Im very excited to say the least. Anyway the car has the basic mods, full exhaust, fmic, pod filter, manual boost controller and its getting a new fuel pump on Wednesday as well, just as insurance against fuel supply problems.

So basically I was wondering about the rev limiter on rb25's, how high can you go on an unopened engine. I know this is a "how long is a piece of string" question. So i was hoping that people could speak from personal experience, i.e how high is your limiters set?

From what ive seen 7,500 seems to be the limit, but im not really sure.

Also with the fuel pump the one to get is the Bosch isn't it? The mechanic said to get that or the walbro, and i said i wasnt sure, ille leave it to him. And just now i read about the walbros being crap and having random failures so i might ring him back and tell him i want the bosch. Sound good?

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https://www.sau.com.au/forums/topic/304063-rb-25det-rev-limiter/
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chubs Community Regular

chubs

Posted
Posted

I know the factory limiter is around 7,200rpm i think you will find power will likely drop after this anyways. But is there really a reason to rev it that high in the first place?

My 33 with front mount, cat back, pod, 10psi best shift point is bout 6k.

And yes bosch pump is the way to go

Branelly Enthusiast

Branelly

Posted
  • Author
Posted

Yeah I agree with your point on power dropping a bit at the high rpms, probably because the stock turbo is running out of puff. As for reasons to rev that high, well basically the higher you rev, when you go into the next gear you are going to be higher in the rev range. And as for you changing gear at 6000rpm, thats not a problem, but dont you notice that power keeps increasing all the way untill red line? I certainly do and therefore ussually change gear at about 6,900. That is if im giving it the boot.

chubs Community Regular

chubs

Posted
Posted
Yeah I agree with your point on power dropping a bit at the high rpms, probably because the stock turbo is running out of puff. As for reasons to rev that high, well basically the higher you rev, when you go into the next gear you are going to be higher in the rev range. And as for you changing gear at 6000rpm, thats not a problem, but dont you notice that power keeps increasing all the way untill red line? I certainly do and therefore ussually change gear at about 6,900. That is if im giving it the boot.

well u have more mods than me so thats possible as no i do not feel the power keep increasing.

also it will shorten your engine life. So i would suggest maybe open her up and build an engine for reving out if thats what you want.

JustinP Mentor

JustinP

Posted
Posted
I know the factory limiter is around 7,200rpm i think you will find power will likely drop after this anyways. But is there really a reason to rev it that high in the first place?

My 33 with front mount, cat back, pod, 10psi best shift point is bout 6k.

And yes bosch pump is the way to go

Factory rev limit is 6900.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
7k. any higher with a stock turbo is pretty pointless

Give this man a medal - post of the thread.

No point taking it any further than 7,000rpm, factory turbo is begging for a gear change by 7k, so why stress for no reason?

R33S2 Grand Master

R33S2

Posted
Posted
Keeping it at 7000 will preserve the motor much better.
7k. any higher with a stock turbo is pretty pointless
Give this man a medal - post of the thread.

No point taking it any further than 7,000rpm, factory turbo is begging for a gear change by 7k, so why stress for no reason?

On mine it is set to 7100 because my HKS2850 turbo drops off around there.

I have done 120,000 kms on a stock motor pushing 320+ HP, drags, track and it still runs sweet, I do have all the support mods needed.

bbe Proficient

bbe

Posted
Posted (edited)

mines on 7900 mate, all those under are just wimps ( yeh im prepared to get flammed it is SAU ) My 20 is even higher =)

whilst sliding wether power drops off or not you need revs, and like you said higher rev so next gear is up in sweet spot whilst changin.

i have power fc and can change this myself when ever i want, so speakin from experience 7 does not cut it.

Better to have it higher rather than too low and not be happy and pay again to get it changed with nisstune !

Edited by bbe
Trozzle Grand Master

Trozzle

Posted
Posted
mines on 7900 mate, all those under are just wimps ( yeh im prepared to get flammed it is SAU ) My 20 is even higher =)

whilst sliding wether power drops off or not you need revs, and like you said higher rev so next gear is up in sweet spot whilst changin.

i have power fc and can change this myself when ever i want, so speakin from experience 7 does not cut it.

Better to have it higher rather than too low and not be happy and pay again to get it changed with nisstune !

Why did this just give me a mental image of Einstein licking a window?

joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

Posted
Posted

i dont really agree, if you are running a stock turbo.... i had 7100 dialed in on mine and it was definately outside the powerband... for drift i do understand that you need higher revs tho...

currently i have 7400 dialed in with the 2835, and i could go higher, but want to preserve the motor

lachlanw Veteran

lachlanw

Posted
Posted

didnt that guy with 485ish rwhp out of his stock internaled 25 (cant find thread) usually rev it to 7500 but when he raised the limit to 85 to avoid changing into 5th just before the line it threw a rod at about 8300 ??

someone else will remember the thread .

bbe Proficient

bbe

Posted
Posted (edited)

8500 that would just be awesome, goodbye ceramic wheels thou lol

At 7900 it still does sound smooth =)

I dont get the Einstein licking a window lol

Oh and their is nothing wrong with Walbro.

Edited by bbe
SXY_33 Collaborator

SXY_33

Posted
Posted

Ive got similar mods,

JJR coilpacks

3" turbo back exhaust

FMIC

Pod filter

Bosch 040

nismo Fuel pressure reg

Hi-flowed turbo

Z32 with nistune

mine is set at 7600 as thats when the power peaked. although i have my shift light set at 6800, by the time i react it get pretty close to the limit.

and u will be very happy with the nistune, i know i am.

meet07 Enthusiast

meet07

Posted
Posted

so will the rb25 head macthed with a bigger turbo able to flow good enough to still make power around 7400-7900??? i have heard good things about the rb20 making its way up to 8 or so but the 25???

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