Just a note to on the oil restrictors between the block and head. I regret using them since I used the stadard RB25 oil pump on my RB30DE and the engine is not a high RPM application. I am not getting oil flooding in the head in the R33 track car that has factory restrictors so I do not intend to use special restrictors for the RB30DE engine when I build it for the R33. I will rather add the additional head oil drain back to the sump.
Nigel
My research and experience with the RB 30 with a high output pump (N1 in my case) tells me that the the head drain doesn't work. Some people think it acts as a sump vent but that is not good either as I think it just blows more oil out the top breathers. If you have a high output pump and run at WOT for extended periods (generally this will happen only on the track) you will need restrictors. I have hydraulic lifters and have two x 1.0mm restrictors.
If you are doing a new engine it is a good idea to drill out the oil return holes to 9.5 or 10mm and relieve the area around the other drains. What solved my excessive oil in the head problems as well as the restrictors was 2 x 20mm breathers from the sump going not to the head but to a catch can. The 30 crank whips up a storm and there is a fair amount comes out of those breathers (and its not blowby as I have done a leak-down test and it was fine).
I have one hose going to the top of the catch can and one to the bottom. As I do not have an extended sump (as really one should have for track work) I fully or slightly over fill the sump and under some conditions oil gets pushed out the breathers so the bottom hose allows it to drain back.
With this arrangement I have been able to complete a full track day without exiting in a cloud of smoke with oil coming out everywhere on top of my engine for the first time in ages.
