GTR intake plenum on RB25

[sweetr33]

basically i bought a hole bunch of goodies, one of which is a gtr plenum, where putting a spacer plate between my head and the plenum to match the studs etc, was wondering if this would bring on results as good or better than the greddy plenum for the rb25? I heard the gtr plenum has fins that guide the air into each cylinder as the greddy one doesnt. can anyone confirm this? I also got gtr fuel rail, injectors,reg and pump too. amongst lots of others

[DoughBoy]

If you have already got the plenum, why don't you actually have a look at it to see if what you heard about it is true?

Also might want to search on this, there was a long thread on this topic a few months ago with pics of both plenums, and how they looked mounted up to the head.

[awurth]

they're not really fins just little ridges top and bottom about half a centimeter high that run from the out side of the plenum towards the inlet runners.

[sweetr33]

could u see both plenums working fairly closely in performance? Well regardless, I have invested in a package which has the gtr plenum so thats the one im stuck with. be it a good thing or a not so good thing.

[sweetr33]

can anyone elaborate? I have seen the ridges inside my gtr plenumnow, has anyone made the adaptor plate before to match rb25 head?

[N I B]

Run your car up on a dyno before and after so you can see how much power you loose.

[lukevl]

Theres positive feedback for you

[N I B]

I am positive it will go backwards.

[PHaT MR30]

short runners on a lower revving engine which makes its power more in the mid range...

not cool.. why u wanna get rid of the RB25 manifold? just get it port matched and flowed?

[lukevl]

i am getting rid of it. I have a GTR plenum and throttle bodies because the original plenum is one of the ugliest things around and I want multiple throttles really bad. It was either that or a Greddy plenum.

[N I B]

Go the Greddy, no contest.

[BBQ]

Greaddy being the big company they are, I’m sure with out a doubt they have invested lots of time and research to get the best performance out of a RB25 plenum they why they made one for an RB25 and one for an RB26 because each motor has slightly difference workings.

Your best bet would be to sell the GTR plenum and invest in a RB25 Greaddy one if you really are that keen to change.

[sweetr33]

I am positive it will go backwards.

Why do u say this steve?? Have u seen this happen before? I thought this would be an improvement over standard>?>?

[lukevl]

Yes Steve, but how do I get multiple throttles onto a Greddy plenum for my Rb25? Either way I'm going to have to do some fab. And I know the GTR plenum works well as a unit. Not sure about the capacity of the Greddy ones either. My car isn't being built for outright power but more so for low down torque/boost response.

[N I B]

If low down torque etc is your thing the stock RB25 intake can't be beaten.

[lukevl]

Thank you for your opinion Steve. However I want multiple throttles and a front facing plenum that is not too large in capacity. Going for the Rb25 plenum and single throttle will reduce my throttle response not to mention the extra intercooler piping.

Oh and it doesn't matter what you are doing - you have to look good doing it.

[aybee]

Oh and it doesn't matter what you are doing - you have to look good doing it.

all well and good but what about:

it doesn't matter what you are doing - you have to look into doing it good!

[lukevl]

Trust me - it will work and work fine. You can tune the car to suit so I am not worried. I have heard flow test results from both plenums and I'll take the GTR one thanks.

Have you ever heard of a GTR plenum flowing unevenly? No I don't think so.

Q for Steve - Yes Zoom magazine found that it lost power in most areas, but can you tell me how that RB20 test applies to my motor? 3lt with modified cylinder head and GT35 0.82 housing? I'll give you a hint - there is no comparison.

[sweetr33]

i dont think that an rb20 comparison would even be accurate to the rb25. Afew more cc's to play with on the 25 so hopefully it should work alittle better than the results of the rb20 one, however i still dont know anything about the results of the rb20 rb26 plenum thing.

[DETurbine]

I am with you lukevl, I am also planning on doing this to my RB25 in the next 6months and am not doubting that there will be an increase in the flow. I would almost put money on it and say that the GTR surge tank flows equaly if not more then the Greddy surge. The individual throttle bodies are also good for around a 1000hp, so you wont have to be worring about upgrading to a bigger single throttle body. Also I would rather spend $250 rather then $700+ on the greddy. When do you plan on doing this?.....I was going to make an adapter plate also, and wouldn't mind seeing how yours turns out.