Compatible DOHC Heads
Three heads can be used for the twin cam conversion.
RB25DE (R32) Head
RB25DE/T (R33) VCT Head
All three heads cc up around the 62-64cc mark.
However, please be sure to double check, there have been cases where people have bought heads that for some reason are way off. Possibly aftermarket.
As a reference point the RB30’s SOHC head cc’s up around the 55 to 58cc mark.
The RB26DETT head from the R32/33 GTR bolts only requires a modification to the head stud holes.
The RB26DETT runs larger studs. All water/oil galleys line up.
The R32 RB25DE head bolts straight up to the RB30E bottom end. All water/oil galleys line up.
N/A valve springs have less tension which may cause issues when running big boost.
Cams and springs are interchangeable with RB20DET items.
The R33 RB25DE/T has variable cam timing (VCT/NVCS); this requires welding of the heads VCT oil feed.
The head still requires oil to its VCT, you will have to tap in to the oil galley and run an oil feed to it. The most common used feed is T’ing into the oil pressure sender feed.
Compare the pictures below to gain an understanding of how the head needs to be modified.