REVscene - Vancouver Automotive Forum


Welcome to the REVscene Automotive Forum forums.

Registration is Free!You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community 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 fast, simple and absolutely free so please, join our community today! The banners on the left side and below do not show for registered users!

If you have any problems with the registration process or your account login, please contact contact us.


Go Back   REVscene Automotive Forum > Technical Discussion > Advanced Forced Induction & N/A Engine Tuning

Advanced Forced Induction & N/A Engine Tuning This forum is brought to you by Racing Greed in Port Coquitlam.
Supercharger vs Turbocharger vs NA? Hondata vs Megasquirt? 94oct vs 87oct? Through technical discussion, let's find out what will the best option for you...

Reply
 
Thread Tools
Old 03-07-2010, 05:20 PM   #1
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
How bad is 3in exhaust on n/a engine ?

Stock 240sx with ka24de, i wanna get a catback, almost all the catbacks are 3in, How bad you think the torque loss with be ? I was thinking it woulnt be so bad considering that its stock headers and stock cat, there is probably enough back pressure from those.. Any thoughts or experience specifically with a 240..

Thanks
Advertisement
bikerman is offline   Reply With Quote
Old 03-07-2010, 05:53 PM   #2
It's like going crazy when you're already nuts
 
jing's Avatar
 
Join Date: Aug 2005
Posts: 5,700
Thanked 2,584 Times in 689 Posts
I went from a 3" to a 2.5" on my old car with a KA and didn't notice much of any difference other than a loss of torque in the upper range
__________________
my feedback
jing is online now   Reply With Quote
Old 03-07-2010, 07:46 PM   #3
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
allright im gunna go 3in. do you know if a 3in catback bolts up to the stock cat ?
bikerman is offline   Reply With Quote
Old 03-07-2010, 10:05 PM   #4
Head Moderator
 
Lomac's Avatar
 
Join Date: Dec 1982
Location: Great White Nor
Posts: 22,646
Thanked 6,409 Times in 2,069 Posts
Just curious... For what reason(s) are you using for going with a 3" cat-back?
Lomac is offline   Reply With Quote
Old 03-08-2010, 09:24 AM   #5
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
Its what is widely available. Most are 3in since lots of people run sr20 or ca18 engines
Posted via RS Mobile
bikerman is offline   Reply With Quote
Old 03-08-2010, 10:38 AM   #6
2x Variable Nockenwellen Steuerung
 
Join Date: Oct 2002
Location: N49.2 W122.1
Posts: 6,176
Thanked 1,174 Times in 704 Posts
Have you done any calculations or modeling? I think it will do more good for your application (not to mention more immediate) than asking.
godwin is offline   Reply With Quote
Old 03-08-2010, 02:09 PM   #7
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
Modeling ? Calculations ?? No. I dont know formulas for airflow based on pipe size. But thanks for that....
Posted via RS Mobile
bikerman is offline   Reply With Quote
Old 03-09-2010, 04:19 PM   #8
I contribute to threads in the offtopic forum
 
Join Date: Oct 2009
Location: richmond
Posts: 2,838
Thanked 1,490 Times in 570 Posts
you will get all the needed back pressure from the manifold down pipe and stock cat.
__________________
Rise Auto Salon

11938 95a Ave Delta
I can be reached VIA text @ 778-232-1465

Oil change special $70 5 liters synthetic oil including OEM filter Fender rolling from $45 per fender
Car Audio:
Focal, Morel, Genesis, Clarion, Scosche, Escort, Compustar, GReddy, Blitz, Tomei, Motul, Endless, Defi, Cusco, Nismo + More


We specialize in:
Custom Car Audio
Race/4x4 Fabrication
Forced Induction
Engine Swaps
General Maintenance
Phil@rise is offline   Reply With Quote
Old 03-09-2010, 06:11 PM   #9
I don't get it
 
azndvdiz's Avatar
 
Join Date: Nov 2006
Location: Burnaby, BC
Posts: 437
Thanked 95 Times in 21 Posts
2.5 is more than enough for an NA imo.
__________________
.
azndvdiz is offline   Reply With Quote
Old 03-09-2010, 08:09 PM   #10
RS.net Licensed Sponsor
 
Join Date: Jun 2006
Location: Vancouver
Posts: 2,808
Thanked 155 Times in 137 Posts
Quote:
Originally Posted by bikerman View Post
Stock 240sx with ka24de, i wanna get a catback, almost all the catbacks are 3in, How bad you think the torque loss with be ? I was thinking it woulnt be so bad considering that its stock headers and stock cat, there is probably enough back pressure from those.. Any thoughts or experience specifically with a 240..

Thanks
I would suggest that you have an exhaust built for you. Use our muffler and tip and have our suggested exhaust shop make a 2.5" exhaust for you. It will make you very happy.
__________________
Overseas Auto

210 E 4th at Main
Vancouver BC V5T 1G5
Telephone - 604 879 6288
Email jim@overseas-auto.com
Toll Free - 1 800 665 5031


Text 604-836-7278

http://www.overseas-auto.com
http://www.piaalights.com
http://www.weberjets.com
http://www.brightsourcehid.com

MSN Messenger z5551212@hotmail.com

We take Interac, Cash, Visa, MC, Amex,

Open 8-5 Monday to Friday, 11-1 Saturday


We have been supplying quality accessories, parts, tires, wheels for 51 years.
Overseas Auto1 is offline   Reply With Quote
Old 03-09-2010, 08:38 PM   #11
Head Moderator
 
Lomac's Avatar
 
Join Date: Dec 1982
Location: Great White Nor
Posts: 22,646
Thanked 6,409 Times in 2,069 Posts
Quote:
Originally Posted by bikerman View Post
Its what is widely available. Most are 3in since lots of people run sr20 or ca18 engines
Posted via RS Mobile
Just because a size is widely available or popular, it doesn't mean it's ideal. I had full 2.75" piping on my old CA18DETT (yes twin turbo). My suggestion would be a 2.25 or 2.5, max.
Lomac is offline   Reply With Quote
Old 03-10-2010, 02:00 PM   #12
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Lomac View Post
Just because a size is widely available or popular, it doesn't mean it's ideal. I had full 2.75" piping on my old CA18DETT (yes twin turbo). My suggestion would be a 2.25 or 2.5, max.
I Know its not ideal but i can pick one up cheap.. I might just fork out the money and get a 2.5..

Thanks for the input.
bikerman is offline   Reply With Quote
Old 03-11-2010, 11:42 AM   #13
Banned (BBM)
 
Join Date: Jul 2004
Location: Vancouver
Posts: 16,142
Thanked 627 Times in 368 Posts
2.25 to 2.5 for N/A
Mugen EvOlutioN is offline   Reply With Quote
Old 03-11-2010, 03:20 PM   #14
RS.net Licensed Vendor
 
RacingGreed's Avatar
 
Join Date: Nov 2007
Location: vancouver BC
Posts: 230
Thanked 107 Times in 25 Posts
The 3" catback won't really make a difference because the stock manifold and cat will be the restriction anyway. The one thing that might cause problems (depending on the catback you use) is where the 3" catback meets the stock cat. Sometimes they don't seal up nicely and you can get an exhaust leak.
__________________
Your ECU Tuning and Fabrication Specialists. AWD Mustang Chassis Load Dyno Onsite

www.racinggreed.com

RG RACING

Tel: 604.554.0170
Unit 110 - 1650 Broadway St
Port Coquitlam, BC
V3C 6P8

Like us on facebook & follow the shops developments and customer cars:
http://www.facebook.com/pages/Racing...40448429329074
RacingGreed is offline   Reply With Quote
Old 03-11-2010, 03:49 PM   #15
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by RacingGreed View Post
The 3" catback won't really make a difference because the stock manifold and cat will be the restriction anyway. The one thing that might cause problems (depending on the catback you use) is where the 3" catback meets the stock cat. Sometimes they don't seal up nicely and you can get an exhaust leak.
Yeah, that's my main concern is getting one that will mate with my stock cat with out problems. Although, the flange is huge on the stock exhaust.
bikerman is offline   Reply With Quote
Old 03-12-2010, 09:23 AM   #16
I contribute to threads in the offtopic forum
 
TheSalesman's Avatar
 
Join Date: Dec 2002
Location: vancouver
Posts: 2,637
Thanked 154 Times in 91 Posts
LOTS of misinformation here about max 2.5" or whatever.
There have been many dynos on a 4cyl engine making more power with a 3" exhaust. Bigger 4cyl like 2.2L and up, not civics. I run a 3" exhaust myself on my prelude and I had a 2.25, 2.5 and then I finally ended up with a 3". You would probably not benefit as much because of your stock header and exhaust so you should change those too if you want more power. Tuning will be everything though.
TheSalesman is offline   Reply With Quote
Old 03-12-2010, 10:55 AM   #17
Head Moderator
 
Lomac's Avatar
 
Join Date: Dec 1982
Location: Great White Nor
Posts: 22,646
Thanked 6,409 Times in 2,069 Posts
Quote:
Originally Posted by TheSalesman View Post
LOTS of misinformation here about max 2.5" or whatever.
There have been many dynos on a 4cyl engine making more power with a 3" exhaust. Bigger 4cyl like 2.2L and up, not civics. I run a 3" exhaust myself on my prelude and I had a 2.25, 2.5 and then I finally ended up with a 3". You would probably not benefit as much because of your stock header and exhaust so you should change those too if you want more power. Tuning will be everything though.
I wouldn't say that it's misinformation. By my suggestion of 2.5" max, I'm trying to give him the best of both worlds. Smaller = better low end torque, Bigger = higher top end. By going for something in the middle, you sacrifice a little on each end, but retain most of the rest. Yes, the stock headers and cat will help with torque, but if he decides to upgrade them at some point, he'll be back at square one if he wants to go for more lower end torque.
Lomac is offline   Reply With Quote
Old 03-12-2010, 02:23 PM   #18
I contribute to threads in the offtopic forum
 
TheSalesman's Avatar
 
Join Date: Dec 2002
Location: vancouver
Posts: 2,637
Thanked 154 Times in 91 Posts
Quote:
Originally Posted by Lomac View Post
I wouldn't say that it's misinformation. By my suggestion of 2.5" max, I'm trying to give him the best of both worlds. Smaller = better low end torque, Bigger = higher top end. By going for something in the middle, you sacrifice a little on each end, but retain most of the rest. Yes, the stock headers and cat will help with torque, but if he decides to upgrade them at some point, he'll be back at square one if he wants to go for more lower end torque.
This theory of smaller exhaust = more torque has been thrown out the window for a few years now. Yeah I know it makes sense but its been dyno proven already that a 3" exhaust makes power through the entire power band. This was done on a bone stock h22. There are a lot of preludes out there running 3" exhausts now and I know this isnt an h22 but it is a 2.4L motor.
TheSalesman is offline   Reply With Quote
Old 03-12-2010, 04:52 PM   #19
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
yeah, the stock headers are pretty good too, comes stock with a decent size 4-2-1 header.. I think im gonna go 3", there is just way more of them on ebay
bikerman is offline   Reply With Quote
Old 03-12-2010, 08:25 PM   #20
Head Moderator
 
Lomac's Avatar
 
Join Date: Dec 1982
Location: Great White Nor
Posts: 22,646
Thanked 6,409 Times in 2,069 Posts
Quote:
Originally Posted by TheSalesman View Post
This theory of smaller exhaust = more torque has been thrown out the window for a few years now. Yeah I know it makes sense but its been dyno proven already that a 3" exhaust makes power through the entire power band. This was done on a bone stock h22. There are a lot of preludes out there running 3" exhausts now and I know this isnt an h22 but it is a 2.4L motor.
Lots of guys running N/A KA24's on Zilvia.net have gone from a 3" to a 2.5" because the added backpressure of the larger piping decreases their max WHP. Also dyno proven.
Lomac is offline   Reply With Quote
Old 03-12-2010, 09:32 PM   #21
I contribute to threads in the offtopic forum
 
TheSalesman's Avatar
 
Join Date: Dec 2002
Location: vancouver
Posts: 2,637
Thanked 154 Times in 91 Posts
well here are a few threads just for you to read up on. 3" exhaust makes power over a 2.5" even on an NA k20.
http://www.honda-tech.com/showthread.php?t=2341715
http://www.honda-tech.com/showthread.php?t=2197695
I know where you are coming from and a lot of people don't believe it. It is really up to you. I speak from experience and not just listen to what all the people say. My friend also runs a 3" exhaust on his pretty much bone stock ka24 and although its not very fast, its fast for what it is. Another reason the people that have shown dynos of just bolting on a 3" exhaust and losing power is 99% because thats what it was....bolt on. You need to tune it to the same AFR as it was doing with the 2.5" exhaust too.


I also run a 3" exhaust on my prelude....can't say it doesn't work. It ran 12's...NA
It also made more power on the dyno although I can't find the dyno right now.
TheSalesman is offline   Reply With Quote
Old 03-12-2010, 11:44 PM   #22
I contribute to threads in the offtopic forum
 
TheSalesman's Avatar
 
Join Date: Dec 2002
Location: vancouver
Posts: 2,637
Thanked 154 Times in 91 Posts
I also went as far as looking on a 240 site to read up about 3" exhaust on NA KA24.
http://www.240sxforums.com/forums/ka...ade-guide.html
Seems to me like....nothing but gains.
TheSalesman is offline   Reply With Quote
Old 03-13-2010, 09:07 PM   #23
It's like going crazy when you're already nuts
 
jing's Avatar
 
Join Date: Aug 2005
Posts: 5,700
Thanked 2,584 Times in 689 Posts
A lot of people just go straight to 3" despite any losses in the lower range because they're likely either going to go KA-T, SR, or RB.
__________________
my feedback
jing is online now   Reply With Quote
Old 03-18-2010, 03:33 PM   #24
OMGWTFBBQ is a common word I say everyday
 
Leopold Stotch's Avatar
 
Join Date: Nov 2005
Location: Vancouver
Posts: 6,044
Thanked 315 Times in 149 Posts
run a 3"

it'll be fine. and loud. but fine.
__________________
1996 Honda Accord
1995 Nissan 240sx
2004 Infiniti G35
2005 Honda Jazz

BuySell Feedback
Quote:
"It's called Sex Panther by Odeon. It's illegal in nine countries... Yep, it's made with bits of real panther, so you know it's good ... They've done studies, you know. 60% of the time it works, every time. "
Leopold Stotch is offline   Reply With Quote
Old 03-22-2010, 07:43 PM   #25
What hasn't Killed me, has made me more tolerant of RS!
 
bikerman's Avatar
 
Join Date: Feb 2007
Posts: 183
Thanked 0 Times in 0 Posts
i did go 3inch, picking it up tomorrow.
bikerman is offline   Reply With Quote
Reply

Thread Tools

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
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -8. The time now is 01:30 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
SEO by vBSEO ©2011, Crawlability, Inc.
Revscene.net cannot be held accountable for the actions of its members nor does the opinions of the members represent that of Revscene.net