hey everyone,

i just brought a stock plenum thats been cut and shut to front facing for a good price! ive heard from some people that its just the same as stock, and some that its bad and will eventually kill the engine. i know there wont be much if any performance improvement. but it will make the engine bay look alot more cleaner. any info on if it is a big no or a yes would be great, i have a bigger turbo 430hp, 555cc injectors, fuel pump, power fc etc. have around 230-250rwkw but need new splitfire coil packs. just to let you know a few mods i have and weather the plenum will be safe. any info would be greatly appreciated.

cheers,

front facing stock plenums will cause damage over time, as pretty much they are not designed to have all the air coming from one end but designed to have it coming from the centre. It won't blow up straight away but will cause servere damager over time

Probably not the best idea, I think the biggest problem would be uneven air distribution to each cylinder causing some to run lean and the others to run rich. If you look at the GReddy plenums the first three runners face away from the front of the plenum and the last three gradually face in the direction of the plenum and the plenum tapers down to combat the distribution issues.

Frount facing plenum= less pipe work=quicker responce i have one and have never hade a problum, you will notice a big diffrence i also have a 120mm gtr fmic and f**k the responce was crazy alot of ppl say lag and damage but all i notice was crazy responce

i have the standard front facing plenum and its destroying my first 3 pistons and destroying the last 3s rings. the first 3 run lean and the last 3 run very rich

edit- but hey who cares lol the performance difference is amazing. pretty sure its the plenums fault causing my piston rings in the last 3 to wear out cause of it running very rich and washing the oil of the cylinder wall

Edited May 3, 200719 yr by timma

i know str8e180 from silvia forum makes rb20 forward facing plenums and has put alot of design into it to combat the air flow dilemma.

My plenum has the 100mm taper at the frount i cant find no brand at all on it, is this what they call the stock frount face plenum? couz now you guys have got me thinking

with uneven air distribution, i heard that you can use the power fc and tune some cylinders to run a little more lean than the others? how long would it be safe to run on the engine approx. i will have about a 250rwkw tune.

Probably not the best idea, I think the biggest problem would be uneven air distribution to each cylinder causing some to run lean and the others to run rich. If you look at the GReddy plenums the first three runners face away from the front of the plenum and the last three gradually face in the direction of the plenum and the plenum tapers down to combat the distribution issues.

nice, hopefully its okay then. because i want to put it on, but dont want big dramas with it. i didnt think there'd be that much of a difference in performance.. how long have you been running your stock front facing plenum for? and also you got pics and how much power you got? cheers mate.

Frount facing plenum= less pipe work=quicker responce i have one and have never hade a problum, you will notice a big diffrence i also have a 120mm gtr fmic and f**k the responce was crazy alot of ppl say lag and damage but all i notice was crazy responce

and thanks everyone for the responses

hey guys im looking at buying a stock modified forward facing plenum aswell, i wanna do it just for a bit of fun, it will make the engine bay look a bit more tidy aswell, but you guys are saying this will kill the motor because of uneven air distribution, how severely will it kill it? this thread kind of stopped me in my tracks

Hi guys,

who make stock modified forward facing plenum and where can I get them?

wanna make my engine bay nice and tidy too, lso, quicker responce..

Thanks

ok after reading quit a few threads about this, it kinda makes sense, uneven pressure,

now my question is will this kind of nip/tuck plenum work if it was put on the car and then got tuned with a pfc?

If you were to put an egt sensor on each exhaust runner i spose you could tune each individual cylinder esp those ones that run leaner due to the air distribution

Refered to the front face mod to standard rb25 plenum

ive had a forwrd facing plenum for about 70000ks now (with gtr cooler)

no dramas, less piping

Hey guys, just reading through this thread. Im just in the finishing stages of doing the 25/30 conversion and just bought a forward facing plennum, not a GREDDY one, just the same mould, as i understood that i needed to either install that, or drop my engine mounts due to the extra height of the 30 bottom end making the engine sit too high and me not being able to shut my bonnet properly. So what have other people done to combat the problem of height in this conversion and are these plennums really f**king the motor or is that just speculation that people speak of like its fact. Makes sense what is being said though

should have mentioned, my plenum is a custom fab, not a greddy copy

if you mod the std plenum you will get problems with flow

if you want a front facing plenum buy one that has been made and tested like greddy and subzero

i run a hypertune on mine and find that they are the best in the market

pascals law. pressure is equal.

but its the non boost condition where they show there short comings

I'm currently building an RB25/30 for my 32, would a standard GTR plenum fit on an RB20 25 or 30? if so wouldn't that be the best bet with the multiple throttle bodies? or some thing simpler like a greddy?

This is the plenum i have the car is getting a rebuild with forged internals and more to run 400hp+

any info on what sort of plenum it is, should i upgrad to a greddy item