Just a quick 1 people. Looking at converting my 2005 sti to twinscroll, so I'm on the lookout for some jdm avcs heads. Is there any difference between say 2002 jdm heads and 2005 or spec c heads? Thanks

 

i think the spec c heads are known as 'big port' heads

the jdm wrx sti avcs heads im unsure of to be honest

 

for the hassel it is i wouldnt bother

 

urban myth the heads have the same part no. its the cams that are different

 

are the jdm wrx cams different to the uk avcs heads?

 

I changed my OEM heads for JDM heads and from a side by side comparison the ports are larger.

 

Remember there are two types of AVCS heads
Early ones just have variabe timing on the inlet cams
From 2005 ish I think, dont quote me on that, and the JDM stuff AVCS is on both cams

 

Got a set of v7 sti jdm avcs big port heads here bro, can confirm the ports are most definitely bigger too, drop me a pm if you want some pics

 

Won't quote you lol, but dual AVCS is MY07 STi onwards only...i.e. hatch.

There are definitely cam differences between JDM and UK, and don't forget that 2006-onwards UK cars are 2.5l whereas JDM stayed with 2.0l.

2005 JDM STi has same cams and heads as a Spec C of the same year.

Have to be honest and say I'm not 100% sure when "big port" heads came in, but I think it was 2005.

It's a minefield!! And I've not helped much lol.

 

You have helped more than me mate
It is a minefield - so check you specfic car guys.
I also think the big port heads came in 2005...but not 100% on this

(BTW Tim the wheels you got off Matty for your wifes car. Were off my car)

 

All JDM New age sti's have large port heads, all 2.0 STI's have single avcs, only Hatch STI's have dual AVCS.

 

Thank you. Just what I wanted to know. Sorry for my uneducated questions lol but would a bugeye be classed as a newage? Thanks

 

Early bugeye uk sti heads are also big port, then they changed to smaller port...
There also has been debates about spec c and jdm cams.. They are actually the same cam..

I wouldn't worry about small port vs big port... There is arguments in favour of both... I would concentrate on trying to get ones with no cracks... This you are going to find very difficult in itself.....