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Old 06-25-2006, 12:22 PM   #17
FuJi K
Scooby Guru
 
Member#: 3687
Join Date: Jan 2001
Chapter/Region: MWSOC
Location: St. Paul, MN
Vehicle:
MY99 GF4 JDM 6spd
NF Performance

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here now the testing on the flow benches......the Spec C head was tested on 28" of water.......Cobb tested on 25" of water.......now that's 3" of difference, meaning that...with more water, it will have to push more water through the ports....

BUT I tell you what though, last night I got a local member to bring out his JDM STi Version 7 heads and WRX head (same or similar casting as the USDM STi heads; Liberty heads) for comparision. We look everything over. The intake ports ARE the same from the 2.5 DOHC NA heads and the JDM STi Ver 7, pressure sure the exhaust wouldn't be any different. The valve size are the SAME in intake AND exhaust; just that the Ver 7 are sodium filled. The splitters & valve guide all looked IDENTICAL. That cleared up A LOT of questions. We're planning on CC'ing the ports to see how much difference in port volume. But so far from what we can tell....it's just the same size, only slighty different where the injector boss is. So believe what you want to believe, we bought looked over everything.

And how are the Spec C heads different from STi heads?
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