Aftermarket Plenum On Rb25de Neo

[Silver_GT]

Title basically states it all, looking at getting a R33 Greddy Style Intake Manifold for my N/A R34, But Ive noticed that the IACV (im sure there are other things) and the manifold in general are different to the R33, so it would seem?

I know it'll bolt onto the motor and all, but wondering if all the other gear will bolt onto the manifold properly? Someone im sure has looked into this deeper than i can (dont have an r33 sitting here to compare to ) So anyone who can shed light on the situation would be gretly appreciated

Cheers

[Silver_GT]

Upon further inspection it would seem the Neo used an idle control motor on the side of the TB, Where r33 uses an aac valve? correct me if im wrong?

But the question still remains, although if im right, im thinking the standard TB wont fit on a forward facing plenum, leaving the motor with no idle control? I need to look into it some more as im probably wrong.

EDIT: so the neo has an AAC valve also, ive just confused myself, back to square one!

Edited March 16, 2009 by Silver_GT

[R34GTFOUR]

I personally wouldnt do it, the price for a greddy plenum isnt worth the gains you would make. If anything, with the shorter runners on the greddy plenum you would lose down low torque, which the rb25de neo has bugger all to start with. That with the piss weak cams the neo has from factory and you dont really have a winner.

But if you must, get the plenum, use a q45 throttle body (bolts straight on and its near on 90mm) and use a r33 aac valve, everything else should work ok. You may need to space the fuel rail since the neo is top feed and the non=neo is side feed (which the greddy plenum is designed for).

If you wanted to spend $1500 on a foward facing plenum (thats what they are worth these days brand new) + $150 for a Q45 + $300ish for other parts, i would source a stock gtr plenum with individual throttles and get it adapted to your head. You'll probably come out with a simular bill but individual throttles > 90mm throttle body

[Silver_GT]

Cheers mate, i was thinking something like using an r33 aac aye, still dunno if im gonna bother, was gonna get a china copy, it'd be purely for looks, but im guessing that the variable butterfly thing in the standard plenum isnt there for no reason? it probly help with low down torque or something? who knows.

Also i hate how the factory plenum goes over the top of the motor, kinda silly if you ask me, but im no engineer and i might just save the forward-facing plenum for if and when it gets a turbo, althought if i end up doing it a write up will be done for all to see

[N-DAWG]

The intake plenum on the R34 GT from what I can see is designed to help power delivery with it being naturally aspirated.

The variable valve in the plenum is a hinderence under boost. I get 1-2PSI increase after that valve opens completely at around 4500revs.

[Silver_GT]

The intake plenum on the R34 GT from what I can see is designed to help power delivery with it being naturally aspirated.

The variable valve in the plenum is a hinderence under boost. I get 1-2PSI increase after that valve opens completely at around 4500revs.

mate pull the plug on the solenoid for that valve and it'll stay open all the time (pretty sure its default is open ay) its not hard to find, back of the motor, left side on top of the rocker cover

[N-DAWG]

I thought it was more to do with running a constant 12v signal to keep it open? If it's just that simple then I'll do it, after having a chat to my tuner to make sure it's not going to mess up the AFR's.

[Silver_GT]

mate id have to double check it so dont quote me, as im not sure weather it stays open or closed when the motor is off, if you can figure that out, then it will do the same with the solenoid unplugged.