How do the JDM Ver 8 heads & cams compare to the US STI heads & cams. Do they flow more, lift higher, have longer duration, are generally more aggressive or what relative to each other. I am doing a 2.5 short block conversion and picked up the Ver 8 heads as well.

http://forums.nasioc.com/forums/showthread.php?s=&threadid=423564&highlight=cam+info


http://forums.nasioc.com/forums/showthread.php?s=&threadid=419230&perpage=50&highlight=cam%20info&pagenumber=2

Ver 8 heads will have the large ports and cams much like the ver 7 spec C I belive. The spec C cams are longer duration but lower lift vs wrx. The ver 7 sti cam has lower lift and duration vs the wrx cam. The wrx cam is the same duration but lower lift vs the 2.5 sti. The 2.5 block likes the lift of the bigger cams but will work great with the ver 8 cam. You can pick up a set of usdm sti cams for ~$150 a stick... and if you are not going to run the block to 7.5-8k RPM then you should think about doing that. The 2.5 STi has small port heads.

Removing V8 cams for US STI cams is a step backwards. Duration is far more important then Lift. Why do you think the 2.5 likes lift? How did you form that opinion? Just trying to understand your statement T.

The reason JDM STI cams have less lift is because with more duration and less lift you increase the RPM range of the heads. The valve is open longer but not as far which reduces the chance of float and or breakage.

CLark

Well I figured if you arent going to use the a 8k redline then why go with the cams made for that. Just use the 2.5s cams... Bad logic?

Maybe not bad logic but I would still rather have the JDM Cams. Those are 8300 rpm cams for a 2.0. Power peak around 7k. Actual testing has shown that the power peak will drop 800 rpm to 1000 rpm with the 2.5 ltr over the 2.0. The Duration here is more important then that bit of extra lift. Remember.. This is a turbo engine.

Cya

Clark

Sniff, sniff, i think i smell a 2.5 block in my future.

AZScoobie reports

The reason JDM STI cams have less lift is because with more duration and less lift you increase the RPM range of the heads.

Clark do you know if the JDM 2.5L Forrester engines recently imported use the same cams as the v8 STi JDM engines? Just a point of clarification. Thanks.

Mike McBride

That might make sense as to why Phil thinks his motor has got more kick vs the US sti. http://forums.nasioc.com/forums/showthread.php?s=&threadid=523486

Originally posted by MZM
AZScoobie reports


Clark do you know if the JDM 2.5L Forrester engines recently imported use the same cams as the v8 STi JDM engines? Just a point of clarification. Thanks.

Mike McBride


Mike.. I have no idea what cams are in the 2.5 forester. Its possible that the cams are different but my guess is that they are the same.

Clark

I am looking at doing the same thing.

I am looking at building a US 2.5 block and putting Ver 8 JDM Sti heads on it. Is it possible to wire in the AVCS?

I have a 2002 WRX.

Nick

Originally posted by Rizzo314
I am looking at doing the same thing.

I am looking at building a US 2.5 block and putting Ver 8 JDM Sti heads on it. Is it possible to wire in the AVCS?

I have a 2002 WRX.

Nick

avcs in a wrx? ya, no problem... search there are a few threads that show what you have to do.