Jump to content
SAU Community

Recommended Posts

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,

Link to comment
https://www.sau.com.au/forums/topic/167293-question-on-front-facing-plenum/
Share on other sites

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 by timma

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 :)

  • 2 weeks later...

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 :D

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

Refered to the front face mod to standard rb25 plenum

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

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

post-12272-1179007045_thumb.jpg

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?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • No, you're wrong, and you've always been wrong about this. The Nismo has 2 sets of openings. One is a real 2-way, and the other is a 1-way. There is no 1.5-way possible with the ramps that they offer. A real 1.5-way does exist. That Cusco stuff I posted is a prime example. If the forward drive ramps are, say 55°, and the overrun ramps are, say, 30°, then you will get about half as much LSD effect on overrun than you do on drive. It is real, it realy works. OK, you're slightly right. The Nismo has 55° and 45° ramps on the 2-way, so it does offer less LSD effect on overrun. But, I think that just means that they've (probably) sensibly established that you do not want actually equal LSD effect on overrun. You just want "quite a lot, but not quite as much as the drive LSD effect".
    • Just wanted to unearth this and post my baby with the new front ❤️😝 Took her to my wedding rehearsal today. Next up is getting wide skirts (after wedding)
    • Yea, that is what I was getting at in my ramblings too. The nismo one actually is a 1.5 way and a 1 way. They don't do a *2* way because a true *2* way would have equal ramp angles. Or is that a true 1.5 way? Realistically I think a "1.5 way" does not actually exist. A diff can either lock in two directions or one. It also doesn't help that a LOT of people in Australia speak about 1.5 way diffs are referring to their 1 way diff.
    • Well, the trouble with that ^^ is: The configuration shown is absolutely a 1-way, not a 1.5-way. There is no way that a 1.5-way can be said to offer LSD action only on acceleration. If Nismo cannot get that right, then it is impossible to believe their documentation. That ^ is not a 1.5 way setup. That is a 1-way.   And so now I have allowed all doubts to flourish and have gone back to look at the MotoIQ video. I originally made the mistake of believing him when he said "this is a 1.5-way" at the ~6:10 mark. Because what he did was take the gear assembly out of the 2-way opening and just rotate it one place to the left to drop it into the 1-way opening. When he dropped it in there, the cam was "backwards" compared to the correct orientation shown in all other photos of that config. The flat shold have been facing the 1° ramp side of the opening, not the 55° ramp side. And I thought, "gee that's cute", but I was concerned at the time, when he put the other ring back on, that the gap between the rings looked like it was wider then in the 2-way config. And then I said a lot of things in my long post on Tuesday that could only make sense if the guy from MotoIQ was correct about what he'd done. BUT... I have now done my homework. I grabbed a frame of the video with the 2-way config, and then grabbed another with the "1.5-way" config, snipped out the cam and opening of that frame and just pasted it direct on top of the 2-way config. I scaled it so that the triangular opening was almost exactly the same height in both. AND.... the gap between the plates is wider with the cam installed in the triangualr opening backwards. That is.... it cannot go together that way. There would be massive force on the plates all the time, if you could even reassemble it.  So, My statement on the matter? The Nismo diff is actually only a 2-way and 1-way. There is no 1.5-way option in it, regardless of what they say. Here's a photo of a real 1.5-way ramp opening from Cusco (along with the 1 way option). And the full set of 1 through 2 way options from their racing diff, which is not same-same as what we'd typically be using, but...the cams work the same. A little blurry, but it comes from this Cusco doc, which is quite helpful. AND.... Cusco do in fact do what I suggested would be sensible, which is to have rings that do 1 and 1.5, and 1.5 and 2. Separately.  
×
×
  • Create New...