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Old 03-25-2020, 10:19 AM   #56
Scooby Guru
Member#: 108051
Join Date: Feb 2006
Chapter/Region: Tri-State
Location: NY
2005 TickingTimeBomb
Jr tuned TT Sleeved


Originally Posted by gunt View Post
these questions could be answered somewhere [ i have spent a good time looking ] but as with the bore size , i have a question with regards to troth size , on std valves size are you increasing it if so how much [ some might not like to say by how much ] we usually get to open them by 1mm on std valves on other brand engines / and this is where i wonder does everyone increase troth size when using bigger valves or are new bigger seats or keeping std troth to increase venturi ,

i seen someone rote that the newer std heads are flowing near b16a head figures , this is a point where i see subaru lacking as these cfm figures obivouslly flow perfectlly adiquatlly for 16-1800cc and the increase in subaru cc only increase the restriction and therfore the hugh fall off in what we see the graphs , cam are really only an attempt to sort the issue
has anyone got a set of cams cut to suit the head they have flowed

I have the d25 heads ported Chambers all matched to (52cc) on a 100mm bore extensive bowl porting with 1mm added before the valve seats. Blended into the ports with extensive matching to the dog leg and straight port exhaust ports. Std aftermarket valves GSC super alloy valves, GSC s2 cams and they do great shimmed GSC beehive springs. On a 6466 turbo. I'm very happy with the combo. Great response great flow all throughout the rpm range.

If you look you'll see that GSC s2 cams are basically a equal grind to a jdm big port cam.
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