Version 4 STi Head rebuild
 

Hi guys,

I've just got myself a set of Version 4 STi heads to use in a 2.5 conversation for my 95 WRX Impreza. As I've been told their are the best to use in this sort of conversation.

The heads came out of a version 4 JDM STi that had covered 50k.

While their out, I was thinking of getting them ported and polished and a general degrease and clean.

The conversation i'm going for will hopefully achieve 400-420bhp.

What other mods to the heads should I consider to get a good strong reliable engine?:thumb: :thumb:

BTTT

Paul @ Zen can sort head porting..

however assuming rest of spec is upto it you don't have to port them for 400~420.. might be something else in the setup better throwing money at??
whats the setup? :)

Simon

My profile is up to ate, all eninge mods that I have are lised in that.

Furture mods at the moment, are 6 speed gearbox, 2.5 bottome end, turbo and posible bigger injectors.

Is the nothing else that needs to be done to the heads, to make them more efficent/reliable/produce more power and so on? Other than port, polisha and flowing them? Stronger springs, lifters etc...??

Have the bore opened up on the heads to match the 2.5 block, would be good for engine reliability.

Banny

you can uprate the valves, springs and cams yes.. but you don't have too for that power level..

Other than opening the head chamber area to match the bore at this level I personally would forget about spending money on the heads. Check your cam clearances are correct and valves are seated and give everything a check over.

Consider the pistons in the 2.5 while its open, a set of after market drop in pistons will raise the power handling capability on the block and give more bottom end reliability..

I've just been quoted £599plus VAT to rebuild, gas flow port and polish my heads. Is that about right?

It will involve a regrind on the cams to make sure they are in good nick, and all round clean up and degrease and all new Subaru parts. Nothing uprated that I can recall.

Then of course it will be gas flowed and the exhaust ports ported to match the headers, and finally the bottom machined to match the 2.5 bottom end.

Never having had a pair of heads rebuilt before I didn't know if this was the going rate.