Flow test results of my Front Facing Plenum

[Sydneykid]

Sorry Steve, maybe I didn't explain that very well...

I sold a COMPLETE RB25DET for $1.5K. Not just the top end.

[Steve]

Sorry, having a bit of a barry tonight:(

[B-Man]

Big prob with going to RB26 inlet setup is that you may have already spent money on a turbo setup which included an expensive exhaust manifold.

The other problem is finding someone in Sydney that knows what they are doing and can do this upgrade.

Then there is: being in the right place at the right time to pick up the RB26 (whole or parts) for the right price. OR Having the time to do the rounds of all the places that would sell this stuff, OR pay someone to do it for you .....

etcetera, etcetera.

It's OK if you have another ride and/or you want to get the best bang for your buck, but sometimes people either pay for, or for-go some mods for conveinience/timeliness sake.

[Sydneykid]

Hi B-Man I buy lots of stuff on the forums, both SA and SDU. You just have to keep looking, have your money ready and move swiftly. The good stuff goes fast.

[Warpspeed]

Sydneykid is spot on, I have been buying individual RB26 bits, and will probably have spent around four grand by the time I have everything. At least it has the advantage that you can see the condition of each part as you buy it. If I ever do it again I would just get a whole complete RB26DETT, they go for about Three grand, but you need to be quick. I will put it all into an RB25 block to keep the same engine number, and stock sump. Saves a lot of trouble.

You will have no difficulty selling your complete RB25DET either, especially while it is still in the car and running.

As far as flow testing goes, I will be able to test at 56 inches (2psi) , as my blower goes to just over sixty, but my latest (largest so far) flowbench is not yet completed. I have done extensive tests on the bare blower though. It has a 7.5 Hp three phase motor, and needs every bit of it. But I would not expect the results to be any different to testing at 28 inches.

A DIY flowbench need not be expensive or complicated, but it requires a fair bit of work and research to get the best results. It is an ideal home project, this one will be my third, and will allow me to reach 600CFM, and be easier to operate.

[BOOSTMEISTER]

As mentioned, it is great to see some actuall testing being done, good work B-Man.

Here is a thought for anyone thinking of doing something different with a plenum. A while ago I saw a pic of a tuner in Japan that had cut the Rb20det runners off a couple of inches from the head and then had welded an RB26dett plenum on...I decided to do this so I took heaps of measurements and they virtually match up.....I bought some more runners and was about to buy the plenum but decided to sell the car.

So, these guys in Japan say that their plenum works very well and flows well also....this may be a good option for those wanting something a bit different, my only issue is that the runner length will be shortened dramatically so I dont' know what this will do to either the top or bottom end of the power ??

[Steve]

Shorter runners I would have thought it would affect mid range everything else being equal. Harder to say when you change the design of the plenum and also the configuration of the throttle body.

Short runners are better for top end - from what I have read anyhow.

Nice idea though, using the rb26 plenum - I think by the time you figure in cost though (probably a dime a dozen in Jap), it may be cheaper to just go trust plenum as everything bolts on and it comes with all the boltage, pipes etc and a nice big red greddy sticker for the top (gotta love the rice:))

[BOOSTMEISTER]

Actually I found heaps of wreckers here in Aust that were wrecking RB26's. Most wanted about $250 for the plenum ?? Not that expensive I thought.

[Steve]

No, that sounds bloody excellent. What cost to modify the plenum for TB and cut and shut to runners?

[BOOSTMEISTER]

Well I was going to cut it my self and prep it then take it to A.R.E to have it welded, I think the welding was going to be the most expensive part but dam they do a good job. From memory the plenum, runners and welding were about $600-$700. They don't line up perfectly so some porting needs to be done on the inside but most people can do that anyway with the right tools. Naturally there are lots of other things to do like relocate throttle cable and fuel filter etc but they are neither here nor there really.

[T0nyGTSt]

$250 + $700 welding etc.

Doesn't make much economic sense IMO.

T.

[Steve]

Ditto Tony,

Buy a trust plenum for around 1200 with an adaptor for stock TB and all the bits you need, everything fits and it comes with all boltage, pipes etc

Yeah its a bit more expensive, but everything works and no guesswork.

Mind you if you had the know how and facility to do it yourself - then it would be a different proposition

[rbs13]

do trust make plenums for the rb20.. ?

[Clint32]

Originally posted by rbs13

do trust make plenums for the rb20.. ?

bingo, the people with rb20s need to have something custom made or stick with stock.

Also I had a look at a Trust plenum the other day and was not very impressed with it, mainly in the casting quality. It would require some cleaning up in the main ports to be of the std runners quality.

[rbs13]

i was so sure they didnt.. sux really! seeing as the rb20's are the better of the rb motors.. haha.. oh no... iv done it

[B-Man]

He he - Funny guy !!!!

[RB20LagWagon]

Coming from the rb30 conversion thread doesnt the rb20 manifold bolt up to rb25. following that, wouldnt greddy rb25 plenum work for rb20 as well.

[Frosty]

nah the rb25 wont fit for some un known reason!

if you want to have a front facing plenum for the RB20 it has to be custom made......i am still waiting on mine because of the problems getting it made with flow etc!

its been about 8months for the plenum and still waiting

but once its done should be good and ill let you guys know prob in a few years when it gets done ahahaha