How Much Bigger Is A Rb25 Turbo Over An Rb20 One?

[Rolls]

I realise the rb25 turbo is bigger but by how much? The reason I ask is I have a gcg highflowed rb20 turbo which I was told was an rb25 one, it was originally on and is being put on an rb25.

I realise the rear housing will be more restrictive making it boost earlier and run out of puff at higher rpm but how much difference is there in the a/r and housing sizes? Especially after they machine the housings out I imagine the difference would only be the a/r.

5% 10% 50% ? If anyone has compressor maps or actual specifications that would be fantastic.

Edited November 18, 2009 by Rolls

[hypergear]

Might be very slight difference, But appears to me they are pretty identical. We make custom bolton .63 rear housings with 3071R 52T sleeve bearing CHRAs using stock RB20det turbo's comp housing. It worked lot better.

[Rolls]

Thats good news, thanks.