Welcome to the North American Subaru Impreza Owners Club Saturday April 10, 2021
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Archives > NASIOC Archives > Technical Forum Archive

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.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
 
 
Thread Tools Display Modes
Old 08-08-2000, 06:45 PM   #1
Trey
Scooby Newbie
 
Member#: 670
Join Date: Dec 1999
Chapter/Region: TXIC
Location: Austin, the Republic of Texas
Post Air flow data - Cylinder Heads

Here's some data I know a few of you have been waiting for. This data is not to be reproduced without my authorization.

I've posted air flow graphs comparing the intake and exhaust port flow of the following cylinder heads:

Stock 2.5L SOHC
Ported 2.5L SOHC
Stock 2.5L DOHC
Stock 2.0L Turbo DOHC (WRX)
Stock 2.2L Turbo SOHC (Legacy Turbo)

They can be found at the following url: http://www.cobbtuning.com/impreza/en...nderheads.html
Just click on the graphs to enlarge them.

Since this is a technical board, I'd like to note that this web page is commercial in nature but the data included is unbiased and scientific. Flow tested was carried out on a calibrated Superflow flow bench at 28".

I will have a seperate page documenting the differences in the heads, in detail, in the near future.

Questions, comments, anything...let me know.

Trey
CobbTuning.com
* Registered users of the site do not see these ads.
Trey is offline  
Sponsored Links
* Registered users of the site do not see these ads.
Old 08-08-2000, 08:46 PM   #2
ColinL
Scooby Guru
 
Member#: 114
Join Date: Jul 1999
Chapter/Region: MWSOC
Location: Wichita, KS and Whoring, OT
Vehicle:
'03 Evo, Rice White
'01 Erion CBR 929

Thumbs up

I would like to say...

I'll be damned. The WRX heads you tested (from what version?) outflowed the 2.5L heads at low lift on the intake side but ended up being no better at .400". On the exhaust side they were equal at low lift and were inferior at high lift.

And the Legacy turbo heads stink.

Were you surprised that the DOHC 2.5 heads flowed very similarly to the SOHC ones considering the differences in valve angles? Was this similarity likely caused by similar runner volume and port shape?

Oh, and will we see dyno results of the porting? Any forthcoming packages with your cams installed in the ported heads?
ColinL is offline  
Old 08-08-2000, 10:32 PM   #3
CNC84
Scooby Newbie
 
Member#: 642
Join Date: Dec 1999
Location: AUSTIN, TX
Thumbs up

Pretty interesting stuff kinda throws the idea of putting the wrx heads on the 2.5 out the window not exactly a whole lot to gain from that move. I wonder why the legacy turbo heads were so crappy in comparison to all of the others was there anything that stuck out about the 2.2 heads as opposed to the 2.0 and 2.5 that was so much different that would restrict things that much?
Chris
CNC84 is offline  
Old 08-08-2000, 10:42 PM   #4
MPREZYA
SCIC
Moderator
 
Member#: 85
Join Date: Jul 1999
Chapter/Region: SCIC
Location: www.themonkeystrunk.com
Post

I can just see Jay UK clamoring for a set of 2.5 heads to swap in . I just wonder about the 2.2L N/A heads.
Rich
MPREZYA is offline  
Old 08-08-2000, 10:51 PM   #5
Jon Bogert
Scooby Specialist
 
Member#: 1133
Join Date: Mar 2000
Location: SE PA
Vehicle:
09 GTR, 02 996 C4S
95 993 C4, 71 911, 04 STI

Question

Um, did you just post the camshaft page, too? How about some more details on the camshafts, for example: How much power do they make? What do they do to the low end? Can you match them with a piggyback ECU and raise the redline a bit? Are you going to incorporate them into your power packages?

I'm real close to buying a turbo kit. Talk me out of it with stories of free revving NA power!
Jon Bogert is offline  
Old 08-09-2000, 12:03 AM   #6
Turk
Scooby Specialist
 
Member#: 1888
Join Date: Jul 2000
Chapter/Region: South East
Location: Charlotte, NC
Post

Great Job!!!!!!
Turk is offline  
Old 08-09-2000, 02:10 AM   #7
Jay_UK
Scooby Specialist
 
Member#: 296
Join Date: Sep 1999
Location: Derby, Derbyshire, England
Post

LOL

I will stick to my nicely flowing modified STI IV heads...

Trey nice work...

But what model do you mean by WRX ? the Euro/Oz wrx ? or the Jap WRX ? and what year ?

J.
Jay_UK is offline  
Old 08-09-2000, 07:04 AM   #8
SteveS
Scooby Specialist
 
Member#: 6
Join Date: Jun 1999
Location: South Jersey
Vehicle:
2007 BMW Z4 M Coupe
Interlagos Blue

Post

Trey ~~ Please keep up the excellent work and articles! This is the type of thing that really benefits the aftermarket community.

SteveS (* 20K turbo'd miles *)
SteveS is offline  
Old 08-09-2000, 07:21 AM   #9
Matt
Guest
 
Member#:
Post

Ok, step one : read Trey's mods and dream
Step two : Rob bank

Why oh Why am I so #&^% poor ?!

Oh well. Got to dream about something I guess.
 
Old 08-09-2000, 07:35 AM   #10
Trey
Scooby Newbie
 
Member#: 670
Join Date: Dec 1999
Chapter/Region: TXIC
Location: Austin, the Republic of Texas
Post

Regarding the WRX heads, to be fair, these were an older, hydraulic lifter version. They're off a closed deck EJ20 but not a STi version. The newer WRX heads are likely better in flow (we would hope).

The Legacy Turbo heads are so poor I think due to a horrid port design coupled with small valves (1.222" IN / 1.105" EX). The best thing for a Legacy Turbo would be to put heads off a later model car, or WRX. I wouldn't waste money on modifying them as it would take alot of work just to bring them up to par with the stock EJ25 or WRX heads.

The WRX heads I tested had a smaller intake valve compared to the EJ25 heads (1.310" vs 1.420"). Exhaust valves are marginally larger (1.250" vs 1.240"). There are definite differences in port designs between them. The EJ25 heads also have better quinch area design (which again, might have been addressed in later models).

I'll work on getting more data up in our technical section as I also have flow data on intake manifolds, throttle body, etc.

And yes, we will have dyno results for everything soon and build packages from those results.

Thanks,
Trey
CobbTuning.com

P.S. If anyone has any heads I haven't tested (ie: 2.2L NA, later model WRX, etc) I'll flow bench them for you at no charge so I can collect more data.
Trey is offline  
Old 08-09-2000, 01:14 PM   #11
Marco
Scooby Newbie
 
Member#: 118
Join Date: Jul 1999
Location: Issaquah, WA - USA
Thumbs up

Guys & Gals (SubieGal that is),

I have been following the progress of these upgrades, basically bugging Trey over the phone, emails and at his shop.
I'm impresed. He has invested a lot of effort and countless hours in getting the heads, cams and all the other goods he's working on to work right. I guess I don't need to tell you this, but I feel that he deserves a lot of credit for making parts and performance upgrades that actually work.
I think he is an example of how aftermaket tuners should work and present their products.

Keep up the wonderful job you're doing, Trey!!!

Cheers,
Marco

[This message has been edited by Marco (edited August 09, 2000).]
Marco is offline  
Old 08-09-2000, 02:05 PM   #12
SCOOBYSHAG
Scooby Specialist
 
Member#: 358
Join Date: Oct 1999
Location: Dallas, TX
Vehicle:
2005 Xterra
Grey

Wink

Trey Cobb yooooouuuuuur my heroooo...
(in my best Ferris Bueller voice)

just kidding! keep up the great work Trey!
SCOOBYSHAG is offline  
Old 08-09-2000, 05:13 PM   #13
CNC84
Scooby Newbie
 
Member#: 642
Join Date: Dec 1999
Location: AUSTIN, TX
Post

Marco I can't agree with you more I just wish some of our other tuners were a little more interested in doing thier own research than in simply repackaging things sold over-seas but hey what can you do there is a place for both types of "tuning" Trey's way is just so much more exciting. I mean he shows us what's going on every step of the way instead of just saying I have this product so come and buy it he gives charts and graphs and explanations as to why he has great products.

***Matt you find the bank and I am game gotta get those heads.**** (just kidding)

Chris
CNC84 is offline  
Old 08-09-2000, 06:40 PM   #14
S.Damery
Scooby Newbie
 
Member#: 1770
Join Date: Jun 2000
Location: Ayer, MA, USA
Thumbs up

Trey,
Interesting reading and nice work! You said that you designed your cams to work with the stock ECU, would they effect emissions? Would your cylinder heads work okay with the factory ECU as well (not that that would be smart, I think Shiv's Tech-II kit would complement this setup nicely). What kind of HP would your Headwork and Cams make? Just curious.
-Shawn
S.Damery is offline  
Old 08-10-2000, 07:12 AM   #15
Trey
Scooby Newbie
 
Member#: 670
Join Date: Dec 1999
Chapter/Region: TXIC
Location: Austin, the Republic of Texas
Post

Shawn,

Yes, the cams work with the stock ECU, though adding a piggyback or Super AFC to correct the A/F ratio is highly recommended. We hope to have the cams dyno tested next week when the dyno we use (RX7.COM) becomes available.

The heads might work with the stock ECU but to see full benefits, a TEC-II, Haltech, or something similiar would be HIGHLY recommended. I'm going to try and dyno the heads/cams with stock ECU but we're also installing a Haltech E6K on the car to show the full gains. We'll also have another cam profile available (later on) for those running a stand- alone computer which will take advantage of a higher rev limit.

Thanks for everyone's patience. We've got many things in the works but we'll try and get the results for these cams and our heads very, very soon.

Best Regards,
Trey
CobbTuning.com
Trey is offline  
Old 08-10-2000, 09:48 AM   #16
cOz
Scooby Newbie
 
Member#: 576
Join Date: Nov 1999
Location: Houston, TX, USA
Vehicle:
1995 Volvo 850 Turbo
Dark Green

Post

Trey is doing the really important work for our cars and is doing a great job with it. Hats off to him for going to the plate for something he enjoys doing.

He is making it really difficult to decide on forced induction or NA. Time will tell...

PS whats up Marco! Trey my cars running great although it is getting the power bug.

Robert cOz-art
cOz is offline  
Old 08-10-2000, 11:38 AM   #17
Turk
Scooby Specialist
 
Member#: 1888
Join Date: Jul 2000
Chapter/Region: South East
Location: Charlotte, NC
Post

Everything sounds great, thank you for your hard work. But I was wondering are you also going to make Cam Gears for the cams?
Turk is offline  
 

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
Analyze my head flow data bmxpunk Built Motor Discussion 19 07-31-2011 03:15 AM
Flow Data? .5mm vs 1mm oversized valves and/or porting? JackHammer Built Motor Discussion 39 12-29-2009 11:19 PM
Vari-Cool Controller Flow Data Logs and Video Coolingmist Water/Methanol Injection, Nitrous & Intercooler Cooling 0 04-09-2007 08:21 PM
Cylinder Head Flow Bench nkeehn Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 1 03-18-2003 05:34 AM
Air Intakes & Air Flow Sensor Norris Normally Aspirated Powertrain 6 10-17-2001 03:11 AM

All times are GMT -4. The time now is 05:59 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2021 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.