RB25 stock head flow figures

[t_revz]

Unfortunately i cant find any good port pictures. only ones before it was sent away for porting. Ill have to get some when i pull the head off later in the year

[t_revz]

Question: "Race Seats" on the scanned paperwork. Implies they were set up properly, multi-angle or radiused or similar? The seats can have a huge impact on the flow - more than the port itself, especially at low lifts.

So I called today to find out if the before/after was just from porting, they said the after will include setting up the valve seats and is the finished product.

Who knows if the porting or valve seats makes more of a difference on it...I guess a bit of both.

[GTSBoy]

The fact that the low lift flow increase is quite good (better than the high lift for the exhausts really) tends to suggest that the seats are contributing to the improvement. Of course, bowl shaping and a few other adjustments to guides and stuff also work on the low lift flow. It's impossible to separate unless someone puts a lot of time and money into it.