Rev Limiter

[nizmo da gizmo]

Hey guys, on my car i rev out to 7000 RPM i was wondering if i could change that to 8,500? I know my rb25de wont handle it but what can i do to make it handle it? just forge the shit out of it? I'm not 100% sure how it works, can anyone please help me?

Edited May 27, 2009 by nizmo da gizmo

[na beast]

pretty sure re-mapping the ecu.. not quite sure.

But i dont recommend doing it at all even with working it to take the force

[astrotristan]

yeh dude itll just fry your engine unles its built to handle it

but im no mechanic - best to ask professional advice

[nizmo da gizmo]

Sweet, thanks for your help guys!

[BezerkR32]

camshafts and valve springs. no use revving stock engine past the point where it makes power.

Sweet, thanks for your help guys!

[mad082]

stick it on a dyno and see if you make your peak power before redline. if you do then there is no point increasing the rev limit, especially by 1500rpm.

[ONE-VIA]

first off why, if your doin it for sound buy a exhaust

but if you want to do it:

valves + valve springs

rocker arm stopers

lighter pistons

stronger rods

etc etc

plus you might want to upgrade cooling (bigger radiator)

[chiksluvit]

rocker arm stopers

RB25s dont have rocker arms like SR20..

[ONE-VIA]

RB25s dont have rocker arms like SR20..

im a ns.com boy wat do i know about skylines lol

[Mr.Massive]

ye remap ECU or get one of those mines ones they lift the RPM but not sure how much- thats a start

[SKiT_R31]

I think the 25det bottom end is reliable to around 7500rpm, lightweight pistons will reduce the pull on the rods giving you a few hundred more rpm. The stock cams will rev that high, but will be way out of their power range, so you will need some higher duration shafts, 270's ought to do it.... You may have issues with valve float, so to be safe you might want new valve springs. Past 8000rpm, esp with cams and increased lift, your going to have issues with the hydrolic lifters, which is something you don't want, do you will need to convert them to solids. If you are revving to 8500, it would be wise to balence the crank, fit new bearings, a higher flowing oil pump, some thinner oil, billet flywheel and aftermarket balancer, as well as under drive pulleys on all your accessories... You will encounter breathing issues with your cams and higher rpm, so twin throttle body's might be a good idea, or a front facing bell mouthed plenum (jun style, should feed them higher revs nicely) and 80mm throttle OR at least a 68mm XF jobby.

quite an expensive excersize. Alternatively, you could drop an RB26DETT head straight on it, sfa modification (head studs, you lose vct, and will have to weld an RB26 header plate on your extractors - which you will need to purchase, but is definately you bang for buck, as it contains the cams, valve springs, ITB's (throttle flow) and lifters you require. On an N/A you might be able to getaway with another 1000rpm to standard, I'm not really sure what 25 bottom ends are good for, its not like you would be putting a lot of power down. With the 26 head there is no reason you couldn't run all the 25 gear.

An RB25DE Mines ECU should have the limiter removed, or at least raised a lot, i know i never found the limiter on my mines ecu, but was never game to take it past 7400rpm (adjusted cam timing with aftermarket 256deg cams took me there) also any form of full aftermarket management will let you move or remove the limiter.

OR forgetting all of the above, if you are just after rice points (which is fair enough, each to their own ) fit a mandrel bent 2" exhaust system (it can flow enough for a stocker 25de don't you worry) with a mandrel center offset muffler or 2 (pending req'd volume) AND NO CANNON, then simply fit an aftermarket tacho (or modify the stock one) to work in 4 or 5cyl mode, you will see your glorious high rpm, and your car will sound like it is screaming.