Plenum Choices ?

[vinnie32GTS4]

hey just wondering..

i was told by changing the plenum u can cause damage because some of the cylinders will run rich and sum will run lean..is this true??

[Bliksem]

your thinking about relocating the throttle body to the front of the factory plenum. Greddy, Plasmaman and other quality aftermarket plenums are flow tested and deliver the correct airflow to each cylinder

[rinmak]

Greddy plenum from Greenline arrived today 885 delivered makes it a bit cheaper than plazmaman

Thats true, they are cheaper BUT you also need to consider that with that plenum you will need to also spend money on either a Q45 TB (150ish?) or the greddy adaptor plate which is $111 delivered on nengun at the moment. Also, dont quote me here but im not sure if you can run the standard fuel rail on the greddy plenum very easily (i think it needs to be modified) so most people then go for an aftermarket rail with top feeders instead.

Dont get me wrong im sure the plenums are brilliant and will make just as much power as any other aftermarket item, but the cost factors above ended up with me just biting the bullet and getting a plazmaman item in the end for $1200 delivered.

Just something to consider for potetntial buyers.

your thinking about relocating the throttle body to the front of the factory plenum. Greddy, Plasmaman and other quality aftermarket plenums are flow tested and deliver the correct airflow to each cylinder

There is actually a discussion on that because tests have proven that even with a genuine greddy plenum the furthest cylinders (5 & 6) run slighly leaner. You can read what SK has to say about it here: http://www.skylinesaustralia.com/forums/in...showtopic=23842

This probably happens with plazmaman as well due to the forward facing long nature of the plenum so dont think im singling out on greddy....just providing facts.

Edited August 13, 2007 by rinmak

[r33_racer]

yet the hypertune plenum supposedly gives damn near perfect airflow to each cylinder especially 5 and 6.

If you have some level of fabricating skills you can make up an adaptor plate for the std throttle body to suit the greddy plenum easy enough. Abit of 10mm ally plate cut to measurements i cant remember right now. Save yourself the 100bux.

You can run the std fuel rail no problems with side feed injectors. The greddy plenum has bolt holes to run both side and top feed rails. Whichever way you want to go.

The plazmaman plenum i believe is designed to take the std throttle body not the q45, so i guess some modifying will need to be done inorder to run it...when i figure it out i will let everyone know unless somebody else has already done it.

[Bliksem]

I purchased the greddy throttle body adaptor for mine, was $75 (not sure how much the shipping was as shipping wsnt itemised)

Another point to note is that you can purchase the Q45's alot cheaper on US ebay

[FineLine]

Unless someone could show me some flow bench results or side by side (before and after) dyno results I think the plazmaman plenum is one hell of an overpriced 1/2 a plenum. 1200 bucks for basically a polished box that sits on top of the stock runners.

Those interested in the performance gains to be had from aftermarket plenums are not going to stop there. In the main they will want to upgrade the t/b and the fuel rail etc so it makes that cost a moot point really.

I went with the greddy job But there is nothing that says I wont change if someone can give me good enough reason to. For the moment tho its greddy all the way. A proven performer.

[r33_racer]

Ill show you dyno results noel after ours is all going....we should see less lag with improved low to mid range torque and power. Those damn short runners kill the low end power and response. But i guess we are looking for just about everything we can get to help us out. 1200 bux is abit much, good thing we didnt pay that price

[FineLine]

Ill show you dyno results noel after ours is all going....we should see less lag with improved low to mid range torque and power. Those damn short runners kill the low end power and response. But i guess we are looking for just about everything we can get to help us out. 1200 bux is abit much, good thing we didnt pay that price

LOL, Your before and after will in no way be a true comparison Mik and you know it ya cheeky young pup.

How are you going to factor out the massive headwork, cams, solid conversion, computer, etc, etc etc.

What I would like to see is a true side by side comparo with zero other changes other than the dyno touchups required to enable each product to do its best.

If i were going to manufacture and market such a product the first thing i would do is test it against the known benchmark and if the results were positive i would sing it to the world.

To date all I have seen is anecdotal evidence, Not conclusive enough for me.

[r33_racer]

im sure they would have done some comparisons...they would be somewhere. I dont think someone would come up with something and not prove it...thats just silly marketing. Ive only heard from workshops who have used them that have seen the benefits of running them in comparison to greddy or std manifolds.

[FineLine]

im sure they would have done some comparisons...they would be somewhere. I dont think someone would come up with something and not prove it...thats just silly marketing. Ive only heard from workshops who have used them that have seen the benefits of running them in comparison to greddy or std manifolds.

I reiterate....anecdotal evidence.

[Al]

Ill show you dyno results noel after ours is all going....we should see less lag with improved low to mid range torque and power. Those damn short runners kill the low end power and response. But i guess we are looking for just about everything we can get to help us out. 1200 bux is abit much, good thing we didnt pay that price

That's what i was concerned/thinking about. The shorter runners would effect low-mid range power/torque. But if the shorter runners decreases low-mid power, then surely it will increase mid-high range power. In which case i am not fussed, as the rb25/30, with a GT30R, is hardly going to have any lag

[Bliksem]

true, mines also going on a 25/30

[silver gts-t]

theres a big thread on calaisturbo.com about plenums and flow tests.