Custom RB20 intake manifold?

[trickey1991]

I see alotta people doing the whole "cutting the intake manifold " thing.and put it to front facing i was just wondering if anyone has cut there mani so there is no crossover the engine for the intake piping. my main concerm would be about air flow to the back cyl. The design of the manifold is to distribute air evenly. People running this would find their back two cyls probably running lean, possibly even the 1st cyl.
I really dont like the look of the cross over. Ive heard mixed reviews some people saying it causes issues and stuff..anyone confirm whether its a good idea or bad?

[Skym]

This is how they did the intake piping on racing version of RB20DET (Gibson GTS-R) -

http://www.youtube.com/watch?v=8_iHWWiVBXs

[DreadedFist]

Plazmaman (i think) makes a beautiful manifold for the rb20. It's about a thousand bucks for the polished version, a little bit less for non-polished or black versions. It looks amazing, imo. They claim 19hp increase on stock boost cars, but dont have any dyno sheets or anything up on their site.

[nelsonmxmarc]

There's a write up in my build thread about this

[Paradis]

I'd seriously take some time to consider whether this is worth it.

It's gonna cost you close to a grande to get a good side feed plenum that will actually do anything for you. There's alot better ways to spend a grande on an RB20. this is coming from someone who had one. if you can afford to spend a 1000 dollars on a part for an rb20 that you won't see alot of actual results (you're playing with fire you get over 300whp), then you should just be making the switch to an rb25.

About the only time i would say it was worth looking at is if you're waist deep in your motor. Like you've bought a Stand-alone, a turbo, fuel system, etc etc and you're already 5+ grande into the engine and switching doesn't make sense. But if we're talking Fuel pump, BOVs and some schleppy piggyback ecus.. don't bother with the plenum.

[Skym]

I agree, if your running 33psi with a TO4R turbo (560hp at engine), would upgrade intake plenum. Otherwise spend money elsewhere.

The Gibson GTS-R in my post above had around 1.7bar (around 25psi) with T3/TO4E turbo, stock intake plenum.

This R32 RB20DET in Canada was producing close to 400whp with stock intake plenum, GT3076R turbo at 22psi -

http://www.youtube.com/watch?v=X_mibuiFSuk

Can do the same with RB25DET stock intake plenum, GT3076R turbo. But only needs around 17psi or so for similar rwhp.

[M13]

btw plazaman is just a fancier top piece and you're still limited w/ the stock bottom runners.

It doesn't cost a grand to get a functional one working.

Also doesn't justify for someone with minor bolt ons.