Welcome to the North American Subaru Impreza Owners Club Thursday April 17, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 05-03-2004, 04:07 PM   #1
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default SOHC RS Head Work

I've finally bought a separate set of heads to get sent off for some work. I'm debating the cost/benefit and reliability of doing a couple of things. I'm looking for about 325-350 WHP as the cap for power.

1. Spring and retainers - These are a must, but should I go with Axis or TWE?
2. Port and polish - I was think of a mild clean up, but since my compression is low I don't want to loose any more low end.
3. Cams - They more than likely would be welded, but the SOHC have a slightly different design the DOHC which can cause shorter cam life. Is the change to the SOHC enough not to worry about this?
4. Upgraded valves - I dunno seems a little bit much

I was leaning towards just the spring and retainers, but I'd like to get some opinions on this.
* Registered users of the site do not see these ads.
seven881 is offline   Reply With Quote
Old 05-03-2004, 04:10 PM   #2
benjaminetanyahoo
*** Banned ***
 
Member#: 41300
Join Date: Aug 2003
Chapter/Region: Tri-State
Location: Midtown West (Lincoln Center)
Vehicle:
2000 New York
MTA

Default

keep everybody here informed because I am thinking about buying a separate set of heads and doing the same.
benjaminetanyahoo is offline   Reply With Quote
Old 05-03-2004, 04:41 PM   #3
White 2.5rs
Scooby Guru
 
Member#: 39936
Join Date: Jul 2003
Vehicle:
99RS TWE&SCAT EJ257
Hydra+HMist+PPG+35R=DEATH

Default

Axis or TWE- its possible both have the same company making their springs

valves...how many psi r u plannin on running?
alex
White 2.5rs is offline   Reply With Quote
Old 05-03-2004, 04:47 PM   #4
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

For now 18-22 on a VF22. I'll more than likely upgrade the turbo if the boost junkie in me wants more. I'd have to upgrade the rods to handle more PSI , which isn't out of the question.

Quote:
Originally posted by White 2.5rs
Axis or TWE- its possible both have the same company making their springs

valves...how many psi r u plannin on running?
alex
seven881 is offline   Reply With Quote
Old 05-03-2004, 06:42 PM   #5
Boostup!
Scooby Specialist
 
Member#: 552
Join Date: Nov 1999
Chapter/Region: MWSOC
Location: Michigan
Vehicle:
SOHC RS-Turbo EJ257
Tec-2 Aquamist 2D

Default Re: SOHC RS Head Work

Quote:
Originally posted by seven881

3. Cams - They more than likely would be welded, but the SOHC have a slightly different design the DOHC which can cause shorter cam life. Is the change to the SOHC enough not to worry about this?
What exactly do you mean when saying "different design can cause shorter cam life" when reffering to SOHC vs DOHC?

Btw if I were you, I would buy all my SOHC components from TWE over any other company because they are the only ones that still truely support and do R&D for the EJ251 SOHC engine. Others have all jumped on the band wagon of the STi and WRX.

Toon
Boostup! is offline   Reply With Quote
Old 05-03-2004, 07:08 PM   #6
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

The SOHC heads have roller rockers. I think this design change reduces friction. Im not 100% on this. That's kinda why I'm posting this too.
seven881 is offline   Reply With Quote
Old 05-03-2004, 07:18 PM   #7
Boostup!
Scooby Specialist
 
Member#: 552
Join Date: Nov 1999
Chapter/Region: MWSOC
Location: Michigan
Vehicle:
SOHC RS-Turbo EJ257
Tec-2 Aquamist 2D

Default

ah...I see what you mean now, I thought you were saying the SOHC camshaft is inferior to the DOHC camshaft design. The SOHC roller rockers DOES help improve cam life and allow for more aggressive opening ramps. hehe....can you tell I like this SOHC head?

How aggressive of a cam profile do you think you want? I am doing some R&D on some pretty aggressive cams designed for turbo application.....but it'll be another month before my car will be running again.

Toon
Boostup! is offline   Reply With Quote
Old 05-03-2004, 07:29 PM   #8
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

I'm not looking for anything to aggressive since this will be a street car. Since I may go for more power later I may address it then, but since my heads will be open I'd figure I do as much as I could. I know TWE has some stage II cams and that may be enough, but I really don't want to loose anymore low end torque.
seven881 is offline   Reply With Quote
Old 05-03-2004, 10:08 PM   #9
Graham
Scooby Specialist
 
Member#: 11931
Join Date: Nov 2001
Location: Winter Park, FL/ SMU @ Dallas,
Vehicle:
2001 2.5 RS Turbo
257/FMIC/T3-T04S

Default

I have the TWE spring and retainers in my car....SOHC RS w/EJ257. Anyway, running 14 psi, I have experienced ZERO valve float issues or anything else. Flawless, and they went in like cake too.

I would get the springs/retainers and nothing else. The stock SOHC cam has been working great for me so far (I'm at about 320 WHP estimated, give or take some). The car just pulls and pulls to redline. Albeit you could get more power with a cam, I didn't think that it was worth it and to be honest I still don't. The size of the turbo makes a much bigger difference in how much power you will make up top.

As well, with a new cam, your going to be sacrificing low-end torque which is nice around town.

Graham
Graham is offline   Reply With Quote
Old 05-04-2004, 12:33 AM   #10
Matt Monson
Scooby Guru
 
Member#: 832
Join Date: Jan 2000
Chapter/Region: RMIC
Location: Teh Ghetto Garage, CO
Vehicle:
99 2.5RS, '85 911
'73 914 and 2012 BRZ

Default

^^^^^Exactly what he said. Do a search for Graham's thread on this when he decided to go that route. It is a good read...
Matt Monson is offline   Reply With Quote
Old 05-04-2004, 01:29 AM   #11
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

Graham,

I agree with this route of doing things as well. The only thing that makes me think is how much the WRX guys love the big port STI heads. Although DOHC WRX heads are different and their CFM's are different I'm curious about the difference between the RS heads and the STI's. I mean from a mechical standpoint what are the differences besides being DOHC?

Quote:
Originally posted by Matt Monson
^^^^^Exactly what he said. Do a search for Graham's thread on this when he decided to go that route. It is a good read...
seven881 is offline   Reply With Quote
Old 05-04-2004, 07:47 AM   #12
PHATsuby
Scooby Guru
 
Member#: 13617
Join Date: Dec 2001
Chapter/Region: MWSOC
Location: MN
Vehicle:
2001 Legacy GT back
to stock is a project too

Default

i have actually heard that the "big port" STi heads have smaller ports than the SOHC heads still.

also where is that thread about someone doing a port and polish on the SOHC heads and it only helping a couple of HP because they already flow so well?

Ben
PHATsuby is offline   Reply With Quote
Old 05-04-2004, 11:13 AM   #13
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

Now that's crazy, but good for us. Seems like the RS heads only need a beffier valve train.

Quote:
Originally posted by PHATsuby
i have actually heard that the "big port" STi heads have smaller ports than the SOHC heads still.

also where is that thread about someone doing a port and polish on the SOHC heads and it only helping a couple of HP because they already flow so well?

Ben
seven881 is offline   Reply With Quote
Old 05-04-2004, 01:57 PM   #14
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

Here's one last question. What would be a good redline for an EJ22T and RS Heads with TWE springs and retainers. 8K?
seven881 is offline   Reply With Quote
Old 05-04-2004, 02:10 PM   #15
Boostup!
Scooby Specialist
 
Member#: 552
Join Date: Nov 1999
Chapter/Region: MWSOC
Location: Michigan
Vehicle:
SOHC RS-Turbo EJ257
Tec-2 Aquamist 2D

Default

IIRC, the TWE springs & retainers will be capable of reving up to 9000rpm w/o valve float but the rev limit of your EJ22T block will probably not, not for long anyway. You'll have to ask your engine builder to recommend a rev limit for the block and stick with that cause it'll most probably be less than 9000rpm. Then you can fine tune it by looking at your dyno plot and see where the power starts to roll off and give another 500 to 1000 or so rpm.
Boostup! is offline   Reply With Quote
Old 05-04-2004, 02:24 PM   #16
8Complex

Moderator
 
Member#: 922
Join Date: Feb 2000
Chapter/Region: MWSOC
Location: Schaumburg, IL
Vehicle:
04 FXT
Red

Default

If you guys are really interested in building heads, I might have a friend that still has a new set of TWE springs/retainers, I have a stg1 Cobb cam, and I have 2 heads with most of the hardware that need porting/machining. I might be able to put them all together to a package to build... would need valves and maybe some misc. hardware.
8Complex is offline   Reply With Quote
Old 05-04-2004, 02:52 PM   #17
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

hmmm.... 8 I'm actually moving near Chi-Town in June and I have a spare set of RS heads. We may be able to work something out. I'm still nervous about the welded cams and EJ22T's are harder to come by these days apperently.
seven881 is offline   Reply With Quote
Old 05-04-2004, 03:42 PM   #18
Graham
Scooby Specialist
 
Member#: 11931
Join Date: Nov 2001
Location: Winter Park, FL/ SMU @ Dallas,
Vehicle:
2001 2.5 RS Turbo
257/FMIC/T3-T04S

Default

Quote:
I agree with this route of doing things as well. The only thing that makes me think is how much the WRX guys love the big port STI heads. Although DOHC WRX heads are different and their CFM's are different I'm curious about the difference between the RS heads and the STI's. I mean from a mechical standpoint what are the differences besides being DOHC?
Porting just isn't going to make THAT much of a difference when your talking about the kindo of power levels that we are shooting for (350-400 WHP). When you start getting into 450-500+ WHP, thats when issues with getting air in the cylinder are going to make a dramatic difference. Additionally, a simple cam will help LOTS more than a mild port job.

I don't know the mechanical differences between the SOHC/DOHC RS and Ver.7 STi heads. I do know that their cams are more aggressive, but something like that can be overcome with some boost.

The thing that leads me to believe that STi/JDM heads aren't that great, is the fact that I have never seen a dyno graph that continues to make power at redline. Jeff Sponaugle has Spec C heads on his EJ257 swap, and IIRC his power falls at redline too.


I'm am currently revving my new motor w/SOHC heads (TWE spring and retainers) to 6800-7000 RPM every day. No problems whatsoever. I know if could go higher, but 7K is enough for the 257 at this point. Any higher and rod issues might one day be a problem.


Quote:
also where is that thread about someone doing a port and polish on the SOHC heads and it only helping a couple of HP because they already flow so well?
I believe that was Xephyr. He had a P&P'd head, and said he would never do it again because the gains just were not enough.
This was also with an EJ22-T, not a 257. So, there is another reason to do just the springs. Make SURE you have a pretty big turbo (VF-22 isn't cutting it)...I'm running the Precision SC34. VERY nice, and full spool by 3500 RPM on the 2.5L. Low boost, lots of power.

Here is a link if you are thinking about a new turbo:

http://www.precisionturbo.net/produc...=Turbochargers


Graham
Graham is offline   Reply With Quote
Old 05-04-2004, 04:26 PM   #19
seven881
Scooby Specialist
 
Member#: 8828
Join Date: Jul 2001
Chapter/Region: MWSOC
Location: K-Town
Vehicle:
01 BRP 2.2T Hybrid
10 VW Grocery Getter

Default

Giddy-up that turbo looks nice (545 crank hp). I know the VF22 is just for phase 2 of the project, which is almost done and I got it super cheap. I may go with a green so I don't have to change my piping, but I dunno/

Quote:
Originally posted by Graham

Make SURE you have a pretty big turbo (VF-22 isn't cutting it)...I'm running the Precision SC34. VERY nice, and full spool by 3500 RPM on the 2.5L. Low boost, lots of power.

Graham
seven881 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: MA - EJ257 Shortblock/SOHC RS Heads/RS Intake Manifold/Alt & PS Aphex28 Engine/Power/Exhaust 21 07-30-2007 01:23 PM
FS: SOHC RS heads smahala1286 Private Vehicle 'For Sale' Classifieds 0 06-17-2006 08:27 PM
22T running PII SOHC RS heads on stock RS ECU idea “what do you think” amorton Built Motor Discussion 21 06-05-2006 05:56 PM
Will '99 SOHC head work with any N/A 2.5 block?? OffRoadWagon Subaru Conversions 17 08-16-2005 04:22 PM
2004 WRX Heads vs. Phase II SOHC RS heads... latinskllz Factory 2.0L Turbo Powertrain 6 06-28-2004 12:28 PM


All times are GMT -4. The time now is 12:18 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.