Welcome to the North American Subaru Impreza Owners Club Tuesday July 22, 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 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 07-18-2003, 06:42 PM   #1
WRXMaster
Scooby Specialist
 
Member#: 19131
Join Date: May 2002
Chapter/Region: SWIC
Location: Las Vegas
Vehicle:
03/0 wrx/2.5rs
Black/blue

Default I need to find alot of power out of exhaust

I have a 2.5rs...............I need as much power as possible out of my exhaust system...............I dont care how loud my car is ...anyone have any ideas?
* Registered users of the site do not see these ads.
WRXMaster is offline   Reply With Quote
Old 07-18-2003, 06:59 PM   #2
ychan
Scooby Newbie
 
Member#: 9418
Join Date: Aug 2001
Location: nyc
Vehicle:
2002 2.5rs
aspen white

Default

can you please be a little more specific?
-y
ychan is offline   Reply With Quote
Old 07-18-2003, 08:32 PM   #3
WRXMaster
Scooby Specialist
 
Member#: 19131
Join Date: May 2002
Chapter/Region: SWIC
Location: Las Vegas
Vehicle:
03/0 wrx/2.5rs
Black/blue

Default

I am running production gt in rally...............Right now I have only a cut off muffler.......................What kind of exhaust gets the most power out of an rs?
WRXMaster is offline   Reply With Quote
Old 07-18-2003, 08:48 PM   #4
nomorefocus
Scooby Newbie
 
Member#: 9677
Join Date: Aug 2001
Location: Peoria, IL
Vehicle:
2002 2.5 RS
Aspen White

Default

Couldn't you just get like a equal length header, no cat, and just a straight pipe back?
nomorefocus is offline   Reply With Quote
Old 07-18-2003, 08:48 PM   #5
joubtt
Scooby Specialist
 
Member#: 33901
Join Date: Mar 2003
Location: San Diego
Vehicle:
04 04 STI
No AWD, Not interested

Default

I recently asked and was told Stromung exhaust/intermediate pipe but there was also a mention of http://www.techworkseng.com/products...stsystems.html
joubtt is offline   Reply With Quote
Old 07-18-2003, 11:26 PM   #6
xfrickx
Scooby Specialist
 
Member#: 7267
Join Date: Jun 2001
Chapter/Region: BAIC
Location: SF CA
Vehicle:
1994 Honda VFR RC-36
2002 Subaru 2.5RS

Default

MRT Header, straight pipe back. Do you have to have a Cat? That or just have equal length headers custom made. Some one has some (BOY I think). I'm no expert though!
xfrickx is offline   Reply With Quote
Old 07-19-2003, 07:44 PM   #7
Dr Ken
Scooby Specialist
 
Member#: 5885
Join Date: Apr 2001
Chapter/Region: NWIC
Location: Portland Oregon
Vehicle:
2000 RS (GME)
SilvAr

Default

Everything that I know about subie intakes and exhausts, I have read here over the years. This is, more or less, one of the most common question raised: How to maximize HP from the available N/A bolt-ons. Data has been accrued, some of questionable validity but is of sufficient quantity (a quality unto itself!) for me to summarize to the best that I recall. Others feel free to correct me. You ask about exhaust, not intake or any other system, so I'll try to regurgitate just that stuff.

Overall the possible HP gains (without concern for street legality) are 5-20 HP tops, roughly as follows:
N/A is optimized with 2.25 to 2.5" inner diameter, fatter than this means low end loss, below this too great restriction.
Headers have best gains with equal length (tuned length):
MRT (header back)- best dyno gains per dollar value.
Brullen (header back)- equal gains, slightly more captial investment.
TWE (headers +/- back)- looks intelligent and like it should be equal gains, but not proven. Advantage having stock locations.
Syms and Scoobysport (headers +/- back)- definitely the most sexy. But gains for N/A not proven (maybe Syms has?) but very likely equal to MRT.

Header wrapping or ceramic coating is of theoretical HP value, but I have yet to see substatiated evidence in our cars, so call that a 1-2HP, tops.

Cat- removed, gutted or low resistance (Random tech, universal)will gain a 2-5HP.

Midpipe Cannister, (resinators are insignificant) - as you're talking about racing, I'd guess simple and lightweight is your interest, the variation of gains within this category is likely minimal (<2HP)and add perhaps 2-5HP over street legals.

I'm hot and feel funny, gotta lay down. Caio.
Dr Ken is offline   Reply With Quote
Old 07-21-2003, 02:18 PM   #8
zzyzx
Scooby Specialist
 
Member#: 815
Join Date: Jan 2000
Location: Florida
Vehicle:
2013 Boss 302 White
2000 2.5 RS Coupe Silver

Default

Quote:
TWE (headers +/- back)- looks intelligent and like it should be equal gains, but not proven.
Well... I don't recall a dyno sheet, but TWE builds Irish Mikes engines for his 2.5 RS for World Challenge. In fact, TWE is the only engine builder for NA EJ25 motors in race applications.

If that's "unproven" than I wonder how a simple dyno sheet from the other header makers constitutes "proven".

Get the TWE header, it's simply superior to the others. That said, you can purchase an entire header back system from them at a reasonable cost.

- Steve
zzyzx is offline   Reply With Quote
Old 07-21-2003, 02:49 PM   #9
BOY
NASIOC Supporter
 
Member#: 232
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: Ft Wayne, IN
Vehicle:
99 RS-T RIP
02 Forster-S

Default

WRXMaster, shouldn't this be better asked in the motorsports forum, as 90% of the folks in here have no clue what the PGT rules are. Secondly, you'll see the most performance out of an equal length header with a high flow cat (PGT is required to have a cat) and a 2.25" catback. Going up to 2.5" piping will likely give you more hp up top but that's not where you'll want it in rally. Ask on specialstage.com or the motorsports forum to get qualified answers from folks who race in the class.
BOY is offline   Reply With Quote
Old 07-21-2003, 02:56 PM   #10
xfrickx
Scooby Specialist
 
Member#: 7267
Join Date: Jun 2001
Chapter/Region: BAIC
Location: SF CA
Vehicle:
1994 Honda VFR RC-36
2002 Subaru 2.5RS

Default

^^^^^^^^^
What he said!
xfrickx is offline   Reply With Quote
Old 07-21-2003, 04:16 PM   #11
Dr Ken
Scooby Specialist
 
Member#: 5885
Join Date: Apr 2001
Chapter/Region: NWIC
Location: Portland Oregon
Vehicle:
2000 RS (GME)
SilvAr

Default

Quote:
Originally posted by zzyzx


If that's "unproven" than I wonder how a simple dyno sheet from the other header makers constitutes "proven".

- Steve
I agree with you zzyzx, and stand corrected, and FWIW, I have TWE and am happy
Dr Ken is offline   Reply With Quote
Old 07-21-2003, 04:18 PM   #12
Compressed
Scooby Newbie
 
Member#: 12271
Join Date: Nov 2001
Location: Colorado
Vehicle:
2012 4Runner TE
KDSS!

Default

Quote:
Originally posted by zzyzx
Well... I don't recall a dyno sheet, but TWE builds Irish Mikes engines for his 2.5 RS for World Challenge. In fact, TWE is the only engine builder for NA EJ25 motors in race applications.

If that's "unproven" than I wonder how a simple dyno sheet from the other header makers constitutes "proven".
- Steve

Thats just anecdotal evidence, it really does not mean anything. All the gains from the built motor could easily just come from headwork and hot cams on these built motors and not the headers. Until a dyno is produced, with before and after results comparing the TWE headers to stock, with all confounding factors controlled, then the TWE header is unproven. Simple as that.
Compressed is offline   Reply With Quote
Old 07-21-2003, 05:05 PM   #13
BOY
NASIOC Supporter
 
Member#: 232
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: Ft Wayne, IN
Vehicle:
99 RS-T RIP
02 Forster-S

Default

Not only that but TWE is far from the only race motor builder . Between Cobb, Axis, Prodrive, Paeco, Jun, Zerosports, MRT, shall I go on?
BOY is offline   Reply With Quote
Old 07-21-2003, 05:38 PM   #14
zzyzx
Scooby Specialist
 
Member#: 815
Join Date: Jan 2000
Location: Florida
Vehicle:
2013 Boss 302 White
2000 2.5 RS Coupe Silver

Default

Quote:
Originally posted by Compressed
[b]Thats just anecdotal evidence ... [snip]


Quote:
Originally posted by BOY
Not only that but TWE is far from the only race motor builder . Between Cobb, Axis, Prodrive, Paeco, Jun, Zerosports, MRT, shall I go on?
Really? Did you miss the "NA" I put in my post? Name just a single example of a Normally Aspirated engine build by any of the organizations that you named in a professional race series today. That should be simple for you, considering your claim, don't ya think?

- Steve
zzyzx is offline   Reply With Quote
Old 07-22-2003, 09:17 AM   #15
BOY
NASIOC Supporter
 
Member#: 232
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: Ft Wayne, IN
Vehicle:
99 RS-T RIP
02 Forster-S

Default

Ohhh, damn you got me. I guess the Cobb and the Paeco motors are just advertised for giggles and grins. Anyway, Steve, TWE may be building the engine but that's irrelevant to this guy looking for a street header... A race motor and a street motor are apples and oranges, same with headers. Seeing as they aren't building blocks (at least publicly) I'd be hesitant to throw one if their 12:1 piston kits in an EJ25 (unless they know something that NOBODY else does). Beyond that the design of their header has way too many bends to be optimal. Its great that it terminates at the stock B pipe but come on, each bend creates venturis which interfere's with flow and creates turbulence. Any fluid path should be as straight as possible, the TWE headers are anything but.
BOY is offline   Reply With Quote
Old 07-22-2003, 12:19 PM   #16
zzyzx
Scooby Specialist
 
Member#: 815
Join Date: Jan 2000
Location: Florida
Vehicle:
2013 Boss 302 White
2000 2.5 RS Coupe Silver

Default

Quote:
Originally posted by BOY
... but that's irrelevant to this guy looking for a street header... [snip]
When sombody states I am running production gt in rally............... I don't usually conclude that this individual is looking for a street motor.

- Steve
zzyzx is offline   Reply With Quote
Old 07-22-2003, 12:33 PM   #17
BOY
NASIOC Supporter
 
Member#: 232
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: Ft Wayne, IN
Vehicle:
99 RS-T RIP
02 Forster-S

Default

who wrote that... must've been my alter ego....

I guess what I was getting at is: is this a dual duty car or dedicated PGT? Also, a full race header will make most of its power up top, not sure if that's what he's looking for. Besides, this whole conversation is moot until we find out WHAT THE RULES SAY.
BOY is offline   Reply With Quote
Old 07-22-2003, 01:36 PM   #18
DanzBorin
Subaru Bounty Hunter
Moderator
 
Member#: 7131
Join Date: Jun 2001
Chapter/Region: TXIC
Location: Houston - Back in the Alief
Vehicle:
2008 STi DGM (3rd
STI) prev 05 STi (white)

Default

He needs a catback exhaust... he can't run full exhaust, especially since he has to retain factory cats...

I would get any 2.25" system that doesn't hang low... so you are looking at Stromung or Brullen basically... really you don't need a muffler, so just get a midpipe and have a local shop fab an axleback pipe for cheap...
DanzBorin is offline   Reply With Quote
Old 07-23-2003, 04:56 AM   #19
Kostamojen
Scooby Guru
 
Member#: 2272
Join Date: Sep 2000
Chapter/Region: BAIC
Location: haha XD
Vehicle:
2013 Subaru 599 :P
Galaxy Blue Sexy

Default

Quote:
Originally posted by BOY
Ohhh, damn you got me. I guess the Cobb and the Paeco motors are just advertised for giggles and grins. Anyway, Steve, TWE may be building the engine but that's irrelevant to this guy looking for a street header... A race motor and a street motor are apples and oranges, same with headers. Seeing as they aren't building blocks (at least publicly) I'd be hesitant to throw one if their 12:1 piston kits in an EJ25 (unless they know something that NOBODY else does). Beyond that the design of their header has way too many bends to be optimal. Its great that it terminates at the stock B pipe but come on, each bend creates venturis which interfere's with flow and creates turbulence. Any fluid path should be as straight as possible, the TWE headers are anything but.
Have you seen all those nutty WRX headers then???!!!

Anyhow, from what weve seen here, the TWE's flow almost too much. The larger diamater piping + the 4-in-one design would probably negate the curvature problems of the pipe.

That being said, I saw one of those older JDM Impreza magazines and it had a photo of this nutty N/A designed header that i'd never seen before that was like a combo of the MRT and TWE designs. It had the straight back design of the MRT, but at where the first stock cat is they combined 4-in-one style like the TWE and went into a high flow cat and straight back from there almost. I wish I could read Japanese
Kostamojen is offline   Reply With Quote
Old 07-23-2003, 09:59 AM   #20
BOY
NASIOC Supporter
 
Member#: 232
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: Ft Wayne, IN
Vehicle:
99 RS-T RIP
02 Forster-S

Default

I've seen the older Syms and Cusco designs and they are laughable from a fluid mechanics standpoint... they are surely an improvement over stock, they're definitely shiny, but the lengths (no pun intended) they went through to make them equal length are ridiculous.
BOY is offline   Reply With Quote
Old 07-24-2003, 04:51 AM   #21
Kostamojen
Scooby Guru
 
Member#: 2272
Join Date: Sep 2000
Chapter/Region: BAIC
Location: haha XD
Vehicle:
2013 Subaru 599 :P
Galaxy Blue Sexy

Default

Ive seen the Syms exhaust too, and this was totally different... i was very impressed by the design, ill try to find it again and scan it.
Kostamojen is offline   Reply With Quote
Old 07-24-2003, 07:21 AM   #22
Slack
Scooby Specialist
 
Member#: 17548
Join Date: Apr 2002
Location: Atlanta, Ga
Default

You mean this?




A friend (and fellow member) of mine had his car built up previously. He had Cobb spicy cams, SYMS legacy headers w/ custom header-back exhaust and a flowmaster muffler. The car was fast. I drove it and was impressed. I recall him running in the 14s and beating WRXs at the 1st Annual Midwest Subaru Shootout. 14s may not be all that impressive, but it was pretty fast for a non-turbo RS.


Mick
Slack is offline   Reply With Quote
Old 07-25-2003, 03:57 AM   #23
Kostamojen
Scooby Guru
 
Member#: 2272
Join Date: Sep 2000
Chapter/Region: BAIC
Location: haha XD
Vehicle:
2013 Subaru 599 :P
Galaxy Blue Sexy

Default

Ya, thats the syms. The one I saw was a tad different though, it didnt have all those funky bends up where the headers connect to the engine, it was more straight like the MRT's up to that 4-way connection and had an angled muffler (which I didnt like, but it kept it more straight in terms of flow)
Kostamojen is offline   Reply With Quote
Old 07-25-2003, 10:25 AM   #24
MY99 2.5GT
Scooby Specialist
 
Member#: 5030
Join Date: Mar 2001
Chapter/Region: MAIC
Location: Martinsburg, WV, USA
Vehicle:
1999 Legacy 2.5GT
05 Legacy GT 06 Armada

Default

OK. Heres what I gather.

It sounds like the stock cat section must be retained. If that is the case, TWE is the only Equel Lenght header set that claims to terminate at the stock cat mounting position. The langauge is a little fuzzy on TWE's sight but it sounds like you could use the stock cats with their header set. A phone call would end our curiousity.

Equel length is by far the best header design for flow and the elimination of backpressure. Both are very important on an NA engine that relies fully on its Suck and Blow strokes to pull in air and push out exhaust unlike a turbo motor that is beeing fed high volumes of compressed air. You don't want back pressure from an improperly designed exhaust that causes the engine to not be able to draw air in.

I like the 4-1 design of the TWE good for top end power but if you look the primaries are a good length which will help with low end power also.

MY99 2.5GT is offline   Reply With Quote
Old 07-25-2003, 10:31 AM   #25
MY99 2.5GT
Scooby Specialist
 
Member#: 5030
Join Date: Mar 2001
Chapter/Region: MAIC
Location: Martinsburg, WV, USA
Vehicle:
1999 Legacy 2.5GT
05 Legacy GT 06 Armada

Default

If you can run aftermarket cats I would definitely go with MRT Headers and cut the cat off to install a 2-1 higher flow one. For 4-2-1 equel length headers MRT has the best design.
MY99 2.5GT 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
Need to get a full tank out of my car in a day..... lavid2002 Newbies & FAQs 22 12-18-2009 04:41 AM
Need to find homes for several types of animals Robson TXIC Private Classifieds 56 10-12-2009 03:45 PM
i'm a corprate whore...and I need to find a new job because of it The Tree Off-Topic 0 12-15-2004 01:51 PM
You need to come get this stuff out of my house! del105 South East Region Forum 15 09-29-2004 10:08 PM
Need to find short or long clip of the new WRC 2001 Mike Moffa General Forum Archive 6 02-23-2001 01:05 PM


All times are GMT -4. The time now is 06:09 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.