2.5 Sti Heads - Perth-WRX.com

Fewtyle · #1 22-08-2007, 08:53 PM

Hey guys.

I have a '98 wrx and i'm looking at going 2.5 for my next engine very soon as I scored a brand new 2.5 forester block for cheap cheap.
A mate of mine has a pair of '06 sti heads for me if I want them, but I was just wondering, as they have avcs, would this work?
What would I need to get this thing going (loom, ecu etc)?
I currently have the autronic smc, would this be compatible with the motor/heads etc?

If its to much of a mission, i'm not really phased just the sti heads are there, so if I can use them, I might as well slap'em on, if not i'll just use my wrx heads (if thats even possible)?

Any info would be great guys, cheers.

Mat

Mister Two · #2 22-08-2007, 09:16 PM

it is possible, but yeah, you may need a new ECU for the AVCS and some rewiring and you wont be able to use your current my98 intake manifold with it as it wont bolt onto the new heads.

Possible, but lots of messing around

REXESS · #3 22-08-2007, 09:22 PM

Buy the heads throw in some big cams w/o avcs wam bam... K Thx Bia

foxey · #4 22-08-2007, 09:45 PM

You can use the heads and just leave the AVCS solenoids disconnected, they will just act like normal cams.

As mentioned you can't use a MY98 manifold with the sti heads, but you can put MY98 wrx heads onto the 2.5 short block. If you have a MY98, this will be the easiest option.

To use AVCS your going to have to change to a motec, autronic SM4 or linkPlus G3. All would have to be wire in for a MY98. The SMC does not do variable valve control.

You could possibly change to a newer subaru ecu, but this is ALOT of work, requiring the newer dash and vehicle loom.

Fewtyle · #5 22-08-2007, 11:25 PM

Thanks heaps guys, and girl lol.

Thats all I needed too know.

Great help as always!

WRXTASY · #6 23-08-2007, 04:16 AM

I would do a LOT or research before getting an Autronic SM4 or Link G3 to make doubly sure that it does AVCS if your keeping the AVCS Cams....

Motec M800 Plug in on 99 WRX's works with AVCS with 6-8 wires to wire in. You would need the Gold Box in a MY98.

J

tuna · #7 23-08-2007, 06:45 AM

or pnp with adaptor loom

maddog · #8 23-08-2007, 06:54 AM

Quote:

Originally Posted by REXESS

Buy the heads throw in some big cams w/o avcs wam bam... K Thx Bia

I believe the AVCS wheels are heavy as well, change them out as Rexess suggested and wulla.

BALISTC · #9 23-08-2007, 08:23 AM

AVCS heads can be run as normal heads...just make sure there is no power going to the solenoids.

You will still have to run the oil lines to the solenoids though, or your cams will seize up nicely.

Probably worth removing the AVCS cams and fitting a nice set of Cosworth billets, or something similar.

foxey · #10 23-08-2007, 08:31 AM

Jamie

After having done alot of research myself I can say with some certainty that the SM4 and LinkPlus G3 will do AVCS, you just need to use a wire in.

And I'm sure as you and stace (and hopefully me) are about to find out, the Motec pnp will do it too, though I suspect you will need to use the later model manifold to get rid of the stepper idle control.