Red Line Limit

[SargeRX8]

Hey all,

I want to ask some questions about the red line on the RB25DET motor and gearbox. Ive read a couple dynos in the rb25 thread and some people have higher than 7000rpm red lines. I am not one to push my car to red line but when I do, I just pop pop pop as I hit the limiter. By what amount would one be decreasing the life of the engine by increasing rpm limit to say 7500? What is it which will have the most strain imposed on it, box, engine, syncros, etc? The reason I ask is sometimes I hit the limiter at only 6900rpm. If I can raise the RPM limit to say 7500 and then use 7000 as my max rpm, that would be awesome, that way I don't have the power flop of missing a shift at 7krpm.

Ive hit 7krpm, 3 times n my car. I never usually go past 5500 - 6000.

Stock top and bottom end with all bolt on mods and the power fc ecu.

This is my current dyno setup on the SS2 hypergear turbo.

The dyno from Tao running full boost(20psi)

The turbo will certainly hold the power beyond red line. I am not doing this to get any extra speed or power, but mainly to prevent hitting the limiter and losing that bit of power. People fit Bee R rev limiters all the time on stock motors and from factory these hit 7krpm so I can only imagine the purpose of installing the rev limiter is to raise rpm and not lower it.

Anyone shed any light on what I can destroy here and if I should or should not do this?

[WYTSKY]

if you have the power fc commander you can change the rev limit as simple as going to settings and changing the value... by the looks of it, lTrent changed it for the dyno as it goes to 7200.

Someone else will be more experienced in answering on more wear and tear with higher rpms but yes it can cause big issues, factory items were not designed to spin that fast etc, but if you rarely are on limiter things should be ok, atleast for a while.

[ARTZ]

Simons running his over 8k..It will handle it but how long for is not certain as your putting strain on everything....Just ask your tuner to tune and set it higher, pretty sure he would do it if you asked its your engine after all..

[TiTAN]

i wouldnt be pushing the hydraulic lifters more than 8000rpm either way thats a lot more stress on the rods/rod bolts than 7000rpm is (its an exponential load/force increase not linear)

[GODZ1LLA]

My tommy kaira r33 (rb25det) revved to 8500rpm and was fine with it...

[SargeRX8]

The car wont be seeing this type of RPM day to day, its simply to create a cloud around the original red line so there isn't that splutter when you hit the limit and lose power. Unless it can be done safely, I won't do it. I can understand the stress on the head will greatly rise. 20psi through it and close to 400hp isn't helping either. Simon is crazy but I do admire his work lol. If I can get my self an RB30 bottom end for cheap and pickup an RB25 head down the track, ill build my motor slowly as a backup if this does go ahead and something goes plunk lol.

[R31Nismoid]

Not really sure what relevance the dyno graphs have to all this...

BUT just up the limiter to 7300-7500 and don't go past 7000?

That way you won't hit the limiter which isn't good for the motor.

Nothing else needs to be considered (gearbox, diff etc).

20psi/400HP is nothing for the RB25 head, nor is 8000rpm. Unless rebuilt just don't push the stocker, it'll last years like everyone else.

[SargeRX8]

Not really sure what relevance the dyno graphs have to all this...

BUT just up the limiter to 7300-7500 and don't go past 7000?

That way you won't hit the limiter which isn't good for the motor.

Nothing else needs to be considered (gearbox, diff etc).

20psi/400HP is nothing for the RB25 head, nor is 8000rpm. Unless rebuilt just don't push the stocker, it'll last years like everyone else.

So it would be nice and safe to increase the RPM just to create the cushion around the red line? The dyno graph was just to show that if I did increase the rpm and happen to take it 200rpm higher, I won't just be running the turbo out of efficiency and creating more heat in the turbo. Ill speak to JEZ about this when I take the car up to him.

[DVS JEZ]

Should be fine. Lets wait and see if the turbo rolls over near redline.

[STATUS]

7600 is the default setting i usually use, 8200 for those that need a few extra legs much over this on a r33 and its touch and go (valve train) the neo is happy to about 8500... but all is pointless if the turbo rolls over @ 7k... a bit of over rev is good to keep you off the limiter.

Its common practice in japan to up the limiter to 8800-9000 on rb's to stop you actually hitting them and destroying oil pump gears.