2-Piece Rb26 Inlet Plenums Being Sold On Ebay, Cast Alloy

[dorifticon]

Hi all

I've been vaguely thinking about upgrading my inlet plenum on my rb26/30, and have noticed that 3 or 4 vendors have popped up on ebay recently selling the same or very similar cast alloy inlet plenums for the rb26.

An example is here:

http://cgi.ebay.com.au/EPR-RB26DETT-Intake-Manifold-Plenum-/290513936378?pt=AU_Car_Parts_Accessories&hash=item43a3fadffa

SOme of the listings state straight out they are copied from the greddy one. In addition to having a larger 95mm inlet, they claim to boltup to the factory throttles and have a much larger internal volume.

THe other advantage is, being a matte alloy finish, they don't have the 'cop bait' look about them that some other polished or chromed ones have.

Just wondering if anyone has purchased one of these yet, and had any comments they'd like to share. I'm particularly interested in:

1) ease of fitment - did things more or less line up and seal at critical points where it is supposed to, including machined surfaces and bolt holes

2) any interference - eg does it foul on the clutch m/c like many other upgrade plenums

3) inlet piping - how much of a hassle is it to source an adapter flange

4) performance - did it make any noticeable change in performance (good or bad)?

5) overall assessment - am I better off paying for a hypertune or similar?

[SimonR32]

There is no market for something like this...

If you want less than say 500rwkw then a standard one is fine, if your getting serious about big top end power there is no reason why you shouldn't be able to afford a genuine Greddy or Hypertune

[R31Nismoid]

As above. Couldn't agree more. I can't see how going bigger is going to offer and performance benefit.

Infact I've never seen results to show the GReddy is any better than factory.

The nismo one makes a minor midrange diff, but for the price its really not justified at all.

[dorifticon]

So what is the key advantage with the hypertune style plenums? Is it the internal trumpets, better shaped runners/plenum, or something else?

I'm going to be retaining the 6-throttle setup, if that makes a difference.

[Beer Baron]

well the nismo and trust plenum both have basically the same principal. they have better air distribution (factory plenum send too much air to cyl 5+6 which causes them to run a bit lean). and they are larger volume. larger volume is basically a benefit to on/off/on throttle response. having a larger volume of air in the plenum before the throttles mean when you crack them open there is plenty of pressure and volume there to fill the head. the better design does increase midrange and response a bit. the nismo one I think is a little better in midrange and the trust one a little better in top end. the hypertune one also seems to be a good design.

as far as the cheap ones go, personally I'd stay away. they are usually so poorly cast it's a joke. all the copy plenums i've seen were ill-fitting and needed plenty of work to fit nicely. for the effort spent you still have an inferior product and it leeches money off the people who spent the R+D to design the thing. the trust ones are not super expensive. nismo ones are a little more so but not too bad used if you can find one.

as far as performance increase don't expect it to do anything magic. i'm running a trust plenum on my 32 with the 2.7 Jun engine and it seems to work fine (with 6 throttle set-up). the car is quite responsive and has great midrange but how much of that is due to the 2.7 and the combo of the cams and 2530s or the tune in the motec or the plenum is anyones guess as the plenum was on it when I bought it.

[dorifticon]

Fair enough. The issues with quality/fitment are enough to decide this issue from my perspective. There is very limited space to work with around the plenum of a GTR so any issues with fitment will rule out any knockoffs as an option. Also the amount of screwing around required to remove the plenum with the motor in the car means I will be doing it once and doing it right - having to remove it because of leaks or gaskets not sealing etc is not really an option.

It seems as if the genuine greddy ones routinely come up for sale for $900-1000, whereas the hypertune ones are around $2k, so I'll probably go with a greddy one at this stage (together with an r33 clutch m/c).

[BoostdR]

I have a RB26/30 and can't help to think the larger capacity will be better. The reduced velocity from the larger intake should also aid better cylinder distribution. The gains due to the butterflies being after the Plenum are not the same as other plenums however. The linkages on the 6 throttle OEM have to be lengthened by 10mm or so. There should be enough adjusment available to do so. Not sure about clearance from the brake lines on the master cylinder. For the money, I will eventually give it a try. The Casting on there is much better than the Rb25 ones.

Matt

[fatz]

i have a real one and a fake

look the same to me

you can have my fake for 150 bux if you want it

[Beer Baron]

lol, do it. fatz is pretty drunk most of the time so there's a 50/50 chance he'll give you the genuine greddy one for $150... worth the gamble I say.

[BoostdR]

haha, I grabbed it anyway. Worth a try.. will give me something else to test on the dyno after my 6boost manifold install.

Matt

[Beer Baron]

well fingers crossed for you that fatz has forgotten which is which...

[Beer Baron]

ps your engine bay will be tight as all hell now. 6 boost taking up all the real-estage on the ex side and trust plenum is bloody huuuge on the inlet side, plus the fact you've got a 30 in there. you will never get a hand down in there again!!!

my thing is tight enough now with just 2530s with the same HKS piping you have and hks manifolds and a trust plenum and it's a standard block jun 2.7.... I had to move my PS res too but it's actually a good thing as it takes it further away from the turbo heat. mines now up near the passenger headlight and radiator support.

[dorifticon]

Actually I reckon the rb30 block sitting the head, and therefore the plenum, up slightly higher would improve access to the lower plenum bolts, and give more hand-space in the critical area which is between the transfer case and the underside of the plenum.

Or knowing my luck it makes it worse, more than likely its the latter.

[BoostdR]

ps your engine bay will be tight as all hell now. 6 boost taking up all the real-estage on the ex side and trust plenum is bloody huuuge on the inlet side, plus the fact you've got a 30 in there. you will never get a hand down in there again!!!

my thing is tight enough now with just 2530s with the same HKS piping you have and hks manifolds and a trust plenum and it's a standard block jun 2.7.... I had to move my PS res too but it's actually a good thing as it takes it further away from the turbo heat. mines now up near the passenger headlight and radiator support.

I have to move my PS tank aswell. What did you use for the lines?

[BoostdR]

Actually I reckon the rb30 block sitting the head, and therefore the plenum, up slightly higher would improve access to the lower plenum bolts, and give more hand-space in the critical area which is between the transfer case and the underside of the plenum.

Or knowing my luck it makes it worse, more than likely its the latter.

Yep ,oil filter is easier to get to aswell.

Matt

[Beer Baron]

as best I can remember it's still using the stock ones. just moved. it;s still about the same distance from the PS pump just different place (now near headlight). I'll have a look. there's only low pres line anyway from res to pump so it's quite easy to change.

[BoostdR]

got the Plenum today, Quality looks pretty good considering some of the cast alloy kits I have received from ebay..

Will get a pre and post dyno

[BoostdR]

ok, first issue...the rubber O'ring seal is to long. lol

[BoostdR]

Second, The alley bolts are to short.. very very easy to strip the thread. Will need to get some 5mm longer.

Edited April 7, 2011 by BoostdR

[XRATED]

hmmm.... dosn't look all that much different to my genuine greddy unit.

bugger!

It'll be interesting to see if there are any gains/losses.

I'm so happy your doing all the testing on alot of parts I'm planning to use shortly. I just won't be going 3lt... stroker for meee and a little (mm maybe alot) of giggle gas.

Cheers

Justin