sti heads vs wrx heads

redwrxhead · 01-04-2009, 06:43 PM

ok so i have a 2.5 block and im trying to decide which heads to go with. what are the differences between the wrx heads, STI heads, and JDM V7 sti heads. i know the AVCS difference but what else? and could i use the stock wrx ecu with either of them besides the wrx heads?

thanks in advance for the info

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Fongers · 01-04-2009, 07:56 PM

Better breathing and sensors. You can make anything work with the wrx ecu but will need some adapters for the cam sensors at the very least...

305mouse · 01-04-2009, 11:02 PM

Here's a fun little chart to use. I copied it from another thread, very usefull. Look at the head volume.

FuJi K · 01-05-2009, 12:53 AM

In factory form the USDM STi heads will flow a tiny bit better at lower lifts because of the bigger combustion chamber around the valves. The AVCS also allows the cams to open earlier and the cams themselves have HIGHER lift than the WRX, but are the same duration.

Overall FLOW of the USDM heads, not so much difference at all. The Ver.7 would have to be the Spec C / Type RA head to have a bigger INTAKE port. All Ver.8 heads will have large ports being GD specific.

For me I just like to keep it simple with ported WRX heads and big cams.

Maxwell Power · 01-05-2009, 01:45 AM

my advice is to match the heads to the bore/block.

ej2007 · 08-20-2016, 07:16 PM

Just wondering if one of these choices is better. The big difference, from what I can tell, is the single and dual avcs. Not sure but don't think I can get the dual avcs feature to work on my car without a wiring harness from an 08, which I am not going to do. other than that the 08 will be the same as the 07, right?

The reason I am asking is because my cam journals are scored from loosing a rod bearing and I need new heads. Both these head are available for the same price.

slowgenius · 08-22-2016, 09:52 AM

Quote:

Originally Posted by ej2007

Just wondering if one of these choices is better. The big difference, from what I can tell, is the single and dual avcs. Not sure but don't think I can get the dual avcs feature to work on my car without a wiring harness from an 08, which I am not going to do. other than that the 08 will be the same as the 07, right?

The reason I am asking is because my cam journals are scored from loosing a rod bearing and I need new heads. Both these head are available for the same price.

Do the least amount of work, it is more likely you will get the car running and enjoy it.

VMOMMO · 08-29-2016, 01:00 AM

V7 JDM has the big ports too, Spec C had a little bit of porting done. V8 and V9 they didn't do any porting work on.

01-04-2009, 06:43 PM	#1
redwrxhead Scooby Newbie Member#: 156834 Join Date: Aug 2007	sti heads vs wrx heads ok so i have a 2.5 block and im trying to decide which heads to go with. what are the differences between the wrx heads, STI heads, and JDM V7 sti heads. i know the AVCS difference but what else? and could i use the stock wrx ecu with either of them besides the wrx heads? thanks in advance for the info * Registered users of the site do not see these ads.

08-20-2016, 07:16 PM	#6
ej2007 Scooby Newbie Member#: 437259 Join Date: Jan 2016 Chapter/Region: NWIC Location: Seattle WA Vehicle: 2007 wrx	07 wrx needs heads. Options 07 sti or 08 sti Just wondering if one of these choices is better. The big difference, from what I can tell, is the single and dual avcs. Not sure but don't think I can get the dual avcs feature to work on my car without a wiring harness from an 08, which I am not going to do. other than that the 08 will be the same as the 07, right? The reason I am asking is because my cam journals are scored from loosing a rod bearing and I need new heads. Both these head are available for the same price.

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01-04-2009, 07:56 PM	#2
Fongers Scooby Specialist Member#: 118239 Join Date: Jun 2006 Chapter/Region: SCIC Location: Beijing and Venice Beach Vehicle: 2002 Built Wagon Wife- 2004 Outback SE	Better breathing and sensors. You can make anything work with the wrx ecu but will need some adapters for the cam sensors at the very least...

01-04-2009, 11:02 PM	#3
305mouse Scooby Newbie Member#: 106792 Join Date: Feb 2006 Chapter/Region: Tri-State Location: Rochester, NY Vehicle: 2005 Saab 92X Stage Pi w/ VF35	Here's a fun little chart to use. I copied it from another thread, very usefull. Look at the head volume.

01-05-2009, 12:53 AM	#4
FuJi K Scooby Guru Member#: 3687 Join Date: Jan 2001 Chapter/Region: MWSOC Location: St. Paul, MN Vehicle: MY99 GF4 JDM 6spd NF Performance	In factory form the USDM STi heads will flow a tiny bit better at lower lifts because of the bigger combustion chamber around the valves. The AVCS also allows the cams to open earlier and the cams themselves have HIGHER lift than the WRX, but are the same duration. Overall FLOW of the USDM heads, not so much difference at all. The Ver.7 would have to be the Spec C / Type RA head to have a bigger INTAKE port. All Ver.8 heads will have large ports being GD specific. For me I just like to keep it simple with ported WRX heads and big cams.

01-05-2009, 01:45 AM	#5
Maxwell Power Former Vendor Member#: 190729 Join Date: Oct 2008 Chapter/Region: NWIC Location: Marysville, WA	my advice is to match the heads to the bore/block.

08-29-2016, 01:00 AM	#8
VMOMMO Scooby Newbie Member#: 408486 Join Date: Dec 2014 Chapter/Region: International Location: Hong Kong Vehicle: 2001 STi Wagon WRB	V7 JDM has the big ports too, Spec C had a little bit of porting done. V8 and V9 they didn't do any porting work on.