I'm all skylined out o the moment so i feel a trip to the toyshop is in order. This brings me back to thinking about manifolds, valves, springs, cams etc, so my research so far...
Early (non VVT) RB25DE cams are 248 duration. RB25DET cams are 240 duration, GTR cams are 240 inlet, 236 exhaust duration.
All the stock VVT and non VVT cams fit straight into the cylinder head without any problems. Some radical aftermarket cams that have high lift require different valve springs, and sometimes head machining to clear the taller lobes. But standard RB Nissan cams all interchange.
The RB25 and RB26 cylinder heads are the same casting, valves, ports, and combustion chambers are identical. There are many minor diferences though. The GTR has mechanical lifters, and different valve springs.
Because the inlet and exhaust manifolds are totally different, some of the studs have been moved so that the nuts are more easily accessible for manufacture/service. Also RB25 uses 10mm head bolts, RB26 uses 12mm head bolts, so the holes in the head are differnt sizes.
So if you are prepared to remove the head, and tap some new holes to shift some studs, the six throttle body setup will fit onto the RB25 head. (not a mod for the faint hearted id have thought)
Anyone know where i can find out information about aftermarket cams profiles in English?
Paul