Rb20 Manifolds On Rb25 Head?

[grunter01]

hey guys want to know if rb20 manifolds fit on rb25 heads?

[Nic_A31]

Intake no, port size is different, I believe RB25 ports are more oval shaped.

Exhaust manifold, not sure, as far as I know they're the same.

[grunter01]

ok thanks for that, can anybody else confirm that the exhaust manifold fits? and that the intake doesnt

Edited May 30, 2010 by grunter01

[Sarumatix]

That is my understanding too. Visually the exhausts look the same (have a 34 and 32 one here). The intake has different port sizes between 25 and 20 (but not between different 25s). However the top half of the plenum to the crossover is the same between 20 and 25.

[bubba]

Intake studs locations are different, 25 ports are bigger (same shape but bigger, I think 25DET ports are also slightly bigger than 25DE IIRC).

Top half of the plenums are not the same between 20 and 25.. the RB20 has the rear two runners staggered closer to the engine whereas the RB25 has all runners in line.

Exhaust side is the same across all RB20/25's.

Edited May 31, 2010 by bubba