SOHC heads on a phase 1 block q's

Chuck · 04-16-2002, 04:35 PM

OK... So I'm about to get my greasy paws on a phase II complete engine for my turbo project. I currently have a DOHC phase I engine in my RS. My project specs call for a phase II block and my DOHC heads that are currently on my car, so I want to swap the heads so my DOHC heads are free to work with. Will I have any issues running the SOHC heads on a completely otherwise phase 1 setup? Any computer problems? And do the SOHC heads have 1 or 2 exhaust ports? Will I have to source a '99 or greater exhaust header?

Thanks!

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8Complex · 04-16-2002, 05:47 PM

I think the exhaust manifolds are different and I know that the intake manifold is different and won't clear if swapping to SOHC from DOHC.

2.5GT · 04-17-2002, 09:27 AM

I had NO problems using my 97GT headers on my new SOHC engine . . . You will be fine. As for the heads, 8Complex is right. You cannot use the DOHC intake manifold/throttle body with the SOHC heads and vice versa. Everything else, however (block to ANY set of heads), lines up fine.

Quote:

Will I have any issues running the SOHC heads on a completely otherwise phase 1 setup?

In a word, yes. If you're gonna use the DOHC ecu with the newer SOHC heads . . . you will NEED TO SOURCE other parts!!!

Search for a thread under my username for Project Frankensubie and you'll see what I mean.

Jason

Chuck · 04-17-2002, 01:33 PM

Cool... I took a look at your Frankensubie thread and have some questions...

The TPS... how do they differ? Is there a possibility of a little rewiring to get the SOHC TPS to work with my DOHC ECU? This would relieve any other issues regarding the TB.

The Cam Angle Sensor... perhaps seeing this one makes it easier to understand. Which part are the teeth that the CAS reads on? Are they part of the cam sprocket, or on another random pulley that the belt rides along?

Thanks!

I see that you're from College Park.... I'm down there every other weekend visiting my gf at school.

bobjr94 · 04-17-2002, 10:37 PM

the cam and crank sensors are the same on all subaru motors, sohc or dohc, that will be no problem...you can swap the throttle body between the 2 intakes, giving your same tps as before...the idle air valve is different though, on the dohc its in the manifold, on the new sohc int in the throttle body...

2.5GT · 04-18-2002, 02:14 PM

I was under the assumption that the crank/cam sensors were in fact different between the model years. Something like 2-tooth vs. 7-tooth designs. I swapped them out, just to be sure. As for the thottle bodies . . . I know FOR A FACT that my DOHC throttle body DOES NOT bolt onto the SOHC intake manifold.

Jason

Chuck · 04-18-2002, 02:57 PM

Ack... I think it'll just be easier to find someone who wants to trade a set of brand new SOHC heads for a new or slightly used set of DOHC heads.

I'll have to set that up when I get my engine into my greasy hands.

Thanks all!

04-16-2002, 04:35 PM	#1
Chuck Scooby Specialist Member#: 791 Join Date: Jan 2000 Location: Danbury, CT 06810 Vehicle: 1998 Impreza RS Brilliant Red	SOHC heads on a phase 1 block q's OK... So I'm about to get my greasy paws on a phase II complete engine for my turbo project. I currently have a DOHC phase I engine in my RS. My project specs call for a phase II block and my DOHC heads that are currently on my car, so I want to swap the heads so my DOHC heads are free to work with. Will I have any issues running the SOHC heads on a completely otherwise phase 1 setup? Any computer problems? And do the SOHC heads have 1 or 2 exhaust ports? Will I have to source a '99 or greater exhaust header? Thanks! * Registered users of the site do not see these ads.

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04-16-2002, 05:47 PM	#2
8Complex Moderator Member#: 922 Join Date: Feb 2000 Chapter/Region: MWSOC Location: Schaumburg, IL Vehicle: 04 FXT Red	I think the exhaust manifolds are different and I know that the intake manifold is different and won't clear if swapping to SOHC from DOHC.

04-17-2002, 01:33 PM	#4
Chuck Scooby Specialist Member#: 791 Join Date: Jan 2000 Location: Danbury, CT 06810 Vehicle: 1998 Impreza RS Brilliant Red	Cool... I took a look at your Frankensubie thread and have some questions... The TPS... how do they differ? Is there a possibility of a little rewiring to get the SOHC TPS to work with my DOHC ECU? This would relieve any other issues regarding the TB. The Cam Angle Sensor... perhaps seeing this one makes it easier to understand. Which part are the teeth that the CAS reads on? Are they part of the cam sprocket, or on another random pulley that the belt rides along? Thanks! I see that you're from College Park.... I'm down there every other weekend visiting my gf at school.

04-17-2002, 10:37 PM	#5
bobjr94 Scooby Newbie Member#: 6176 Join Date: Apr 2001 Chapter/Region: NWIC Location: Roy,WA Vehicle: 85 Brat,95 Impreza 05 Baja- Blue,Red& Purple	the cam and crank sensors are the same on all subaru motors, sohc or dohc, that will be no problem...you can swap the throttle body between the 2 intakes, giving your same tps as before...the idle air valve is different though, on the dohc its in the manifold, on the new sohc int in the throttle body...

04-18-2002, 02:14 PM	#6
2.5GT Scooby Specialist Member#: 2697 Join Date: Oct 2000 Location: Olney, MD. Work in McLean, VA Vehicle: 2000 Celica GT-S Spectra Blue	I was under the assumption that the crank/cam sensors were in fact different between the model years. Something like 2-tooth vs. 7-tooth designs. I swapped them out, just to be sure. As for the thottle bodies . . . I know FOR A FACT that my DOHC throttle body DOES NOT bolt onto the SOHC intake manifold. Jason

04-18-2002, 02:57 PM	#7
Chuck Scooby Specialist Member#: 791 Join Date: Jan 2000 Location: Danbury, CT 06810 Vehicle: 1998 Impreza RS Brilliant Red	Ack... I think it'll just be easier to find someone who wants to trade a set of brand new SOHC heads for a new or slightly used set of DOHC heads. I'll have to set that up when I get my engine into my greasy hands. Thanks all!