Hiya guys, whats the actual difference between v3 and v4 heads and how can you identify the difference between them?

Cheers Guys

 

None AFAIK. Mick (merlin24) is the expert on these.

 

The head Castings/valvetrain/and cams are the same, although some of the late Version 4 engines came with the later single bolt cam belt tensioner(not head related though) - the difference is between the WRX and STi Version 3 and 4 heads.
It has been said that the Vers. 4 STi heads came with milder cams(lift & duration) but i have never seen any difference in the cams TBH.

WRX/UK Version 3 + 4
Composite Head Gaskets.
IDN/EDN Valves.
48mm Orange Coded Valve Springs.
Outer Shim Buckets 33mm OD.
LHB/RHB Head Codes.

STi Version 3 + 4
Thick MLS Head Gaskets.
IH/EH Valves.
56mm White Coded Valve Springs.
Inner Shim Buckets 33mm OD.
LHB/RHB Head Codes.

Hope this helps you scoobycraig.

Mick

 

absoltue spot on mate! Really appreciate it dude.

 

No worries

 

LOL I swear there is nothing Mick doesn't know about v3/4 engines. I've lost count of the amount of times I've had to ask him something. But having had a set of WRX4 and a set of STi3 and STi4 heads apart, the two STi versions looked the same to me.