Hey guys,

We are finishing up work on a few heads that we have here. First up:

JDM STI V8 BIG PORT HEADS
-Genuine JDM STI V8 Big Ports (includes heads, no core charge)
-Genuine JDM STI V8 cams / valvetrain
-Repolished, line honed for high rpm operation
-valve guides replaced
-New nitrided shimless buckets
-Pressure tested
$1899 Shipped!!
http://www.gruppe-s.com/stuff/V8Headsb.jpg

GRUPPE-S STAGE 2 HEADS
-Includes heads (no core charge)
-Cosworth 278 Camshafts
-Helix Ti Valvetrain
-Gruppe-S Port & Polish
$2799 Shipped!!NO CORE CHARGE!
http://www.gruppe-s.com/Subaru/subeng/JDMhead.jpg

*5 angle valve job is available
*Valve upgrade available

Thanks,

Gary
gary@gruppe-s.com
510-783-5300
510-783-4300 fax

Quick question... what does it take to get the JDM heads to work on an USDM STi and keep the AVCS functional.

Are the cam gears included? Do they use the same gears as the USDM STi?

Whats the compression ratio (approximately) with thise heads on a standard USDM 2.5L motor?

Just wondering... I get mixed information about the heads...

PM or a post here is fine... whichever you prefer. Thanks.

Quick question... what does it take to get the JDM heads to work on an USDM STi and keep the AVCS functional.

Are the cam gears included? Do they use the same gears as the USDM STi?

Whats the compression ratio (approximately) with thise heads on a standard USDM 2.5L motor?

Just wondering... I get mixed information about the heads...

PM or a post here is fine... whichever you prefer. Thanks.

To drop the JDM heads on the USDM STI, you'll need to reline bore the heads and run USDM STI cams. The reason for this is the STI is a reverse pickup cam position whereas the JDM STI uses a straight hall-effect sensor. If you want to run the complete JDM valvetrain you'll need some form of stand-alone EM, for example Motec. I'm not sure if the Hydra can accomodate DBW & standard hall effect, you'd have to give them a call.

As for compression you're looking at (as I recall) 9.2:1 with the JDM V8 heads. To be totally honest a fully ported / built STI 2.5 head will flow as well as if not better than the JDM V8 heads.

Cheers,

Gary
gary@gruppe-s.com

Hi Gary,

I will soon start the build of a new engine for my old '02

I've bought these JDM STI V8 BIG PORT HEADS
I plan buying an OEM STI 2.5 engine localy
I know I will not be able to have AVCS running with my poor ECU
But I don't need to change the cams as stated above ?

If I want to reach a decent CR, what's the better way ?
1 - throwing new forged pistons to decrease CR or
2 - reline bore the heads ?

I'd rather go #1 to have forged pistons instead of machinist cost.

Thanks to Gruppe-S for all the parts on my car ! :cool:

Hi Gary,

I will soon start the build of a new engine for my old '02

I've bought these JDM STI V8 BIG PORT HEADS
I plan buying an OEM STI 2.5 engine localy
I know I will not be able to have AVCS running with my poor ECU
But I don't need to change the cams as stated above ?

If I want to reach a decent CR, what's the better way ?
1 - throwing new forged pistons to decrease CR or
2 - reline bore the heads ?

I'd rather go #1 to have forged pistons instead of machinist cost.

Thanks to Gruppe-S for all the parts on my car ! :cool:

Hi, do you mean new 2.5 shortblock or complete new engine? I would reline hone the heads if you want to run the USDM STI 2.5 cams - they have a bit higher lift and duration - since you won't be running AVCS the pickup will be a non issue, just run the WRX pickup sensor and the WRX intake cam gear. I would also do the pistons to keep the compression in line rather than going with a thicker head gasket. Also keep in mind that this motor would be much better suited for high octane gas as the head space is much smaller (in diameter) than the STI 2.5 heads. If you are running pump gas, you may be better served to port the STI 2.5 heads and just keep the block as a whole. But as always, there's many ways to build a high performance engine. :)

Cheers,

Gary
Gruppe-S

Hello GARY,

Now I've choosen you 2.0 shortblock, I'm wondering if I must put the AVCS solenoid or if I can just put a cap ?
I know that I must feed the oil line.
I also know I will have to hook my stock cam sensor on the driver side.
I will be running with my 02 ECU with no AVCS capabilities.

Do you have some other trick in mind that I should know ?
What thickness of head gasket to use ?

Best regards.

Chris.