Rb30/26... Should I Go Aftermarket Plenum Or Stock 6 Throttles?

[BoostdR]

I am also building a Rb30/26. I have asked Nathan from HiOctane which Hyper tune Plenum would suit....here is the correspondence

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Hi Matt,

It depends what you are using the car for. If you are using it for street use then yes they are good(6throttle Hypertune). However if you are just going for outright power then you are better off with a single throttle plenum.

What size did you need those pistons in?

Regards,

Nathan Welland

Sales And Marketing

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I use the car for street and track days, The drag strip in Adelaide is closed

I am a firm believer in achieving maximum average power and torque.

What gains will the 6 throttle plenum achieve at my target power/Flow?

Matt

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Hey Matt,

The plenum itself does make more power than the standard one. Once you reach over 400kw atw it is no longer the plenum that becomes the restriction it is the throttle bodies. The 6 throttle is better for over all response not maximum power figures.

Regards,

Nathan Welland

Sales And Marketing

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Hmmmmn, That's hard to believe since the combined area of the 6 butterflies minus the shaft is still more than the single TB. I guess the extra turbulence caused at the inlet causes the issue.

So you would say.

6 TB Plenum for GT-SS, 2530, GT2860R-5

Single TB Plenum for Big Singles

I guess I'm right on the line.......I think the 3ltr will give pretty decent response so very hard to say which will make more average power....

hmmmn

Matt

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Oh sorry I didn't realise you are running a 3L ( now that I look back over the emails I see you did say 30/26 ) On a 3L the multi throttle is not worth it single all the way. We are using a single on our new R34 race car which is a 3L.

Regards,

Nathan Welland

Sales And Marketing

Edited April 10, 2008 by BoostdR

[600hp]

If you are all praising the Nismo plenum, have any of you seen results from them?

I've been lucky enough to have a couple of diffrent plenums on our car.

For an all round driver i would recomend a single 90mm unit, this is if you arn't going to make over 1000hp.

If so, i would then step up to a 100mm unit.

As for the ITB setups call Troy from XS-Engineering over in the states and ask him what he thinks of the Nismo itb plenum.If you don't want to call him, He told me that they back to back tested the Nismo to the stock plenum and it made no extra power anywhere and it felt the same on the street.

[R31Nismoid]

In what setup? (regarding the Nismo)

All good and well, if it was say a 350awkw setup, i wouldnt expect no difference really

[Swiper the Fox]

He told me that they back to back tested the Nismo to the stock plenum and it made no extra power anywhere and it felt the same on the street.

that statement does not surprise me at all....its really a very similar unit in shape, volume and construction to a stocker.

The best aftermarket plenums are made right here in Aust. why look anywhere else.

I use and recommend Hypertune plenums for both street (multi throttle) and track (single throttle)

And before all you people cry "but thats a drag car"....Mark Berry and Russell Neuman would back up my statement with real back to testing and results on their circuit GTR.

Edited April 10, 2008 by DiRTgarage

[BoostdR]

that statement does not surprise me at all....its really a very similar unit in shape, volume and construction to a stocker.

The best aftermarket plenums are made right here in Aust. why look anywhere else.

I use and recommend Hypertune plenums for both street (multi throttle) and track (single throttle)

And before all you people cry "but thats a drag car"....Mark Berry and Russell Neuman would back up my statement with real back to testing and results on their circuit GTR.

They use the 6 throttle body setup

[DCIEVE]

so has anyone actually measured exhaust temps (or even better individual cyl afr's)?? 6 doesnt seem to be the worst from what we've been able to see

Edited April 10, 2008 by DCIEVE

[Adriano]

I would be interested to see results such as above for afr and ex temp, as there are many things that can effect these independantly, not only inlet manifold distribution. My % that i use on the PFC came from looking at plugs after power runs.

[DCIEVE]

afr for individual cylinder is more $$ than i can justify, hopefully one of the bigger outfits/race teams have seen it worth looking into though

all the plots show 5&6 running hot on on cruise and light throttle, then when there is load (boost) it turns around...

[unique1]

that log posted by dcieve is my car and it shows 4 hottest on every run, ive added 3% fuel in cylinder 4 and it still needs a touch more i reckon, that run was 18psi boost and 560rwhp if that matters, im yet to push it any further, the afr's are very very rich too so plenty more in it.

[bubba]

^^ Brad, you using standard gtr plenum setup?

[DCIEVE]

he is yes, my results are also on std plenum and look almost identical

[bubba]

Do you have any tuning advise for a gtr plenum then? (I will be using a single throttle body if that makes any difference)

P.S. I've seen Brads' car in person and damn it's angry!

Edited April 11, 2008 by bubba

[700HP-GTR33]

I will be keeping my standard fuel rail and the 550cc injectors I've got in there but have no other option than to go forward facing plenum (space constraints). Will be using a GTR plenum chamber mated to my stock runners (via a flange welded to the cut runners) so I can retain the current injector setup.

Any idea what % increase your tuner used on cyl's 5 & 6?

Not 100% sure...depends on how badly the plugs have been burn't.

It would be trial and error until you got it spot on and saw no plug burn.

Anyway..........the answer to your question.......to make what power you need and can possibly use an after market plenum

is just going to waste money.......but as I alway say......you will at least have bragging rights.....

[bubba]

Unfortunately I don't have the option of using my factory plenum, pipework will just not fit with a high mounted GT35R on my RB30.

I will take everything on board here (and my tuner has problem got a fair idea of what he needs to do) and hopefully get a nice even tune across all cyl's.

[Sydneykid]

that log posted by dcieve is my car and it shows 4 hottest on every run, ive added 3% fuel in cylinder 4 and it still needs a touch more i reckon, that run was 18psi boost and 560rwhp if that matters, im yet to push it any further, the afr's are very very rich too so plenty more in it.

Did you flow check the injectors before you put them in?

Cheers

Gary

[DCIEVE]

both cars have cleaned and flow tested injectors, I asked they record the results when mine were done but the shop claimed there was no real measurable difference so didnt bother. but i think its unlikely for us both to have a lower flowing injector in 4 (and in that case it should also stay the hottest... off load and on?)

edit- both have twin feed rails with centre return if that has an effect

Edited April 11, 2008 by DCIEVE

[unique1]

yes Gary i had my 1000cc injectors flow tested and they were spot on apparently, i got them done by 2 different shops and they both said they were all the same, as i thought that was the issue with the last motor melting pistons

my plenum is stock still, and on my first stock rb26 with 700cc injectors i remember no 4 piston was the one that cracked a ringland and that was on a totally different setup (different turbos, inj, intercooler, valves, etc).

i think DCIEVE is on the money saying 6 is the hottest on cruise, light throttle and soon as boost is on its changing which are the hottest.

How do all u guys know number 6 is the leanest? have u done seperate 02 sensors readings on each runner? or it only numbers from a flow bench?

anyone else happen to have logged egt's on each runner before?

[Bumblebee]

its funny to read how it seems most workshops are saying to use a large single throttle body when most of the countries 9 sec cars run stock manifolds???

its easy to see that theres more than enough there if it can do 9's