Originally Posted by
raiden571
.....the cams, the cams are why. gsr cams have more lift and duration then b16/b17 cams do. but then, ctr and itr cams are more agressive then that even. and im pretty sure that the valves and springs are stronger too. but, a gsr head does not flow as well as a b16 head does NA, but, under boost, a gsr head is more ideal because of the shape of the combustion chamber and i think the ports are different too, but, they also yield a higher compression. so, in my opinoin a true poor mans itr should atleast have the same valvetrain, other wise its nothing like an itr/ctr head
oye
stock flow:
PR3(B18)>P72(GS-R)>PR3(B16)
modified flow:
P72(GSR)>PR3(all)
compression:
P72>PR3(all)
as you can see modified the p72 will beat it out in both sections. unmodified the pr3 from the ITR has bettter flow, but the compression loss is greater than what is gained from the flow, so it's a mute point.
the gsr head is hands down the best b-series head that was produced, the only reason the ITR got the pr3 head is because there were too many stockpiled from the old b16's.
cam profiles are a whole other story, but it's not like it matters, without the compression to back up the more agressive profiles there isn't much to gain. the type-r merely overcame this by using pistons with an increased dome volume to increase compression.