can a stock plenum hack it?

[gobiz]

For big hp mods chasing 250-300+rwkw on a rb25det, is it a must to use a fwd facing plenum a la Steves greddy one?

How high can u go b4 u max out the stock plenum?

[lwells]

General concensus from the Mines Response thread was that you shouldn't touch the plenum, particularly if you are concerned with response. I think SydneyKid said that he is yet to find an aftermarket plenum that improves upon the stocker.

LW.

[sweetr33]

my mates r33 made 345@wheels with stock plenum, still had much more in it, doesnt runa programmable computer yet, i beleive that there are very good for street applications, in drag circumstances then u would change it

[gobiz]

lwells:can u point me towards that thread?

sweetr33, was that 345rwkw or hp? without an engine management system?????? Is that from a reliable source?

[Steve]

Dont need an aftermarket plenum. The stock one will be fine. Bottom line is it depends on what you want.

lwells, have you actually tried fitting a front facing plenum? the only person I know of that reckons he hasnt had gains from it is SK - EVERBODY else, who has one fitted thinks its a good thing. Then again, SK does see an advantage with bigger hp (if I rember correctly), so your statement is a bit misleading. If side facing plenum was better, everyone would be converting to them. Ask yourself, how many side facing plenum conversions do you see out there?

The gains wont be huge, but think about this, if you remove 1 - 2 metres of 2.5 or 3 inch pipe from your inlet, do you think it will have no effect? Why do the japs go to such huge lengths to keep the intercooler pipes so short? shorter pipework will mean better response. Another mate of mine just fitted a front facing plenum, and he reported the same gains I noticed - crisper throttle response and stronger bottom end/midrange - which is pretty important once you start fitting larger turbos imho, esp for a street car.

Think of the stock manifold - guys in NZ make over 400rwkw with the stock manifold - does it make it an optimal deal? no, an aftermarket one is better, but it does support the power.

I have also seen a Jap R34 GTT with 480ps (claimed didnt see a dyno) with stock plenum. So can it be done? Yes. Is it optimal? I dont beleive so. If you budget will stretch I would recommend it, if you dont have the funds, I wouldnt be too stressed.

Is a front facing plenum necessary? I dont think so, and the evidence would support that.

Is a front facing plenum better? I do think so, and there is evidence (mine, others and market driven) to support that.

sweetr33, I would love to see a dyno. I think your mate was pulling your (or his own) leg.

[lwells]

gobiz: http://www.skylinesaustralia.com/forums/sh...=mines+response

Steve: I meant that in the Mines Response thread the concensus -- well, SK at least since he was the main one to comment from memory -- was that aftermarket plenums don't improve performance, at least in terms of response. Sorry if that wasn't clear...

LW.

[Revhead]

Apart from being able to efficiently support more hp, my other biggest reason for putting a front-facing plenum on is so that I can get at the spark plugs without removing any pipework. And it looks cool

[sweetr33]

oh woops forgot to mention that, i was there to see it with my own eyes, and no it definately wasnt rwkw, it was 345 hp. Its like a reprogrammed ecu to suit his cams, turbo, injectors etc, it came from japan like that.