As the heads will be off the car for another rebuild, I am thinking of AVCS heads.

Is it worth all the extra cost if I have V4 heads on my 2.5 converted WRX?

I would like to max out my AF20G turbo with the max drive-ability for the road so spool up is the priority.

 

Hi,

If your going for a forged build then i say go for AVCS heads. Im running AVCS in my v3 sti ra. You will need an ecu is capable of controlling AVCS.

 

The engine is forged, and I have a Simteck etc.

I would need the additional wiring and then sort an inlet manifold as I use the V1 type at the moment, I need spacers anyway to get a decent inlet sorted for the V1 inlet.

I wqas actually thinking of changing the ECU again, but keeping my options open at the moment. I was just woundering if the difference between the two set-up would be night/day or would I just get a small increase in drivability/power. I may be better off spending the £ on ported heads. I doubt if I will change the turbo in the future as 20g is enough.

 

Anyone ?

 

Avc,s heads everytime,no shims to jump out, most are crack free, its a no brainer.

 

I am looking into the costs now, but I think the V3-4 STI heads do not have the shim problem as its under bucket.

 

You will either need a newage inlet manifold or you will have to modify your current manifold to make it wider and then use adapters. If you go with the newage manifold you will then need to modify the wiring for the AVCS, TPS and ICV. Not a simple modification process.

 

Not worth the cost if all your going to be doin is maxing out a 20g IMO

 

I know I like making things unnecessarily complicated, but what about the way you converted my 2 sets V4 heads to shimless?

Having said that, trying to find v4 heads, without cracks, is a pain.

 

You might also want to get the combustion chambers opened out, to match the 2.5 bore.

 

Hi, the V4 heads are on the motor already and as I have a HG problem the heads and motor are comming out (Mod for 2.5 done already), so the question was should I upgrade ? Looking at all the data I can see the V4 heads are quite good, and I think there is not alot of difference in inlet manifold as far as performance. I need to get a good flow to the intake of the turbo, so will be playing about with the fuel lines and adding a spacer to give me the clearance I need to get a direct straight entry.

I was thinking the new head design and variable cam timing would give me better spool, and a little more advance in the higher RPM for more power , but its probly going to be a minimal increase, I am probly better off spending more £ elswhere. Next trip to Scotland for a new map me thinks when its all complete I hope for 400/400 and a good spread of power.

 

What about - Supertec valves, new springs/retainers and spring seats, bronze guides, shimless conversion, port and polish. What cr are you running?

 

CR is about 8.5 : 1 , I like the higher CR , helps spool, as its not a power mad motor, as its Open Deck.