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Rb25 Na Vs Rb25 Turbo Heads

tones

By tones,
in Engines & Forced Induction

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Cubes Grand Master

Cubes

Posted
Posted

The R33 RB25 non turbo and turbo heads are essentially identical. I'm unsure if the n/a heads run slightly softer valve springs or not but the cams, valve size, port size etc are identical.

The R32 heads are based on the RB20DET head with regards to their inlet port design. The inlet ports are larger than the RB20DET ports (~5mm all round), valves etc are all basically the same size as the R33 RB25 heads.

The R32 inlet manifold and plenum is not interchangable with the R33 rb25 heads.

You can use an R32 Rb20DET plenum on the R32 Rb25DE inlet manifold as they too are identical.

The R32 Rb25de inlet manifold vs rb20det inlet manifold simply has larger runners to match that of the r32 rb25de larger ports.

So to answer your question..

Just wondering if they need different plenums or if the same plenum should fit both heads.

Thanks

No, it can't be done, they are different.

Cubes Grand Master

Cubes

Posted
Posted

The R33 RB25 turbo and non turbo heads run the same plenum and inlet manifold.

The R32 RB25 (which is ONLY non turbo) people also make plenums for. RIPZ is the only one that I know of that does the R32 Rb25 non turbo short runner plenum. If you wish to keep your runners that aid low end torque you can simply drop on a rb20det aftermarket plenum. There's a bloke on calaisturbo.com that does them for around $700, JDcustom I think his name is. You can also use the more expensive plazman plenum.

So you have a few options,

  • 2 years later...
Cjmartz2k Proficient

Cjmartz2k

Posted
Posted

Sorry to bring up a REALLY old thread, but can somebody confirms whether or not the turbo vs. n/a R33 heads are the same casting or not? I don't car about springs, lifters, cams, etc. Just the casting (same number?). The n/a heads are plentiful here in junkyards and go for around $180, so I wouldn't mind taking a spare or two back with me to the states.

phantom r33 Rookie

phantom r33

Posted
Posted
Thanks for the help Cubes. I thought it might be the case. Do you know if anyone is making plenums to suit the non turbo heads?

PS Does anyone want to buy a plenum to suit rb25 turbo heads!!!! Good price!!

how much and what brand?

i am looking at getting one in the near future, and could buyit now and install later.

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