2.5 or 3" exhaust? 68 dart 360
#1398702
03/07/13 05:58 PM
03/07/13 05:58 PM
|
Joined: Feb 2003
Posts: 1,306 Laveen, Arizona
GTSDart340
OP
pro stock
|
OP
pro stock
Joined: Feb 2003
Posts: 1,306
Laveen, Arizona
|
Im putting exhaust on my dart, mostly stock 360. In a few years I'm planning on a 408 stroker. Should I go with 2.5 or 3" exhaust?
1949 International KB-2 "Mater" - 302/T5
1968 Dodge Dart GTS "The Drat" - 340/727
2006 Dodge Magnum R/T - Hemi
2016 Dodge Durango Limited - 3.6
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: rapom]
#1398705
03/07/13 06:56 PM
03/07/13 06:56 PM
|
Joined: Jan 2003
Posts: 75,062 U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,062
U.S.S.A.
|
Quote:
2.5" is plenty as the guys in the fast series are running 2.5" and running in the 9's
fixed
I think 3" would be too much on a 360 ... then again they put 5" on a 5.9 cummins
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: rapom]
#1398706
03/07/13 06:58 PM
03/07/13 06:58 PM
|
Joined: Dec 2007
Posts: 646 VA.
mosweethemi
mopar
|
mopar
Joined: Dec 2007
Posts: 646
VA.
|
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: GTSDart340]
#1398707
03/07/13 07:23 PM
03/07/13 07:23 PM
|
Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
3". I believe any neckdown aft of the header collector restricts flow & therefore hurts power & you want no restriction & the least amount of backpressure from there rearward in a 4 stroke eng. Gas speed/scavenging is a seperate pri tube dia/length issue. But a 3" setup is going to be VERY loud & you'll need every ex trick in the book to make the noise liveable, X pipes, addit'l glasspack muffs alongside the leaf springs & maybe add some sideways capped 1.5 ft long pipes welded to the 2 bends over the axle (helmholtz resonators iirc). Ain't tried it but reportedly it is an accoustical godsend for noise reduction. Best might be those trick muffs that open up when you get on it I forget what they are called or some cable or electric operated cutouts along with restricted muffs (keep em quiet till the money is in the hands of a neutral 3rd party ). 2.5" would be troublefree. 3" would be a certain amount of gain but would be alot more work/planning. Mandrel bends everywhere.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: GTSDart340]
#1398708
03/07/13 07:43 PM
03/07/13 07:43 PM
|
Joined: Apr 2005
Posts: 15,134 Kelowna, B.C. Canada
DPelletier
I Live Here
|
I Live Here
Joined: Apr 2005
Posts: 15,134
Kelowna, B.C. Canada
|
Don't bother with 3" unless you plan on over 500hp. Also, don't negect the muffler selection. Dave
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: DPelletier]
#1398709
03/07/13 08:01 PM
03/07/13 08:01 PM
|
Joined: Feb 2007
Posts: 2,578 sweden
1Fast340
master
|
master
Joined: Feb 2007
Posts: 2,578
sweden
|
Quote:
Don't bother with 3" unless you plan on over 500hp. Also, don't negect the muffler selection.
Dave
whats the point in building a 408 if you are not shooting for that kind of power?
i say go for it and like said before chose the right mufflers for it! 3" usualy gives a nice deep sound
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: DPelletier]
#1398710
03/07/13 09:05 PM
03/07/13 09:05 PM
|
Joined: Sep 2003
Posts: 1,168 Vancouver, WA
MoparMarq
super stock
|
super stock
Joined: Sep 2003
Posts: 1,168
Vancouver, WA
|
Quote:
Don't bother with 3" unless you plan on over 500hp. Also, don't negect the muffler selection.
Dave
x2
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: pinkduster]
#1398712
03/07/13 10:01 PM
03/07/13 10:01 PM
|
Joined: Jan 2003
Posts: 7,798 Lyons, CO
MileHighDart
master
|
master
Joined: Jan 2003
Posts: 7,798
Lyons, CO
|
As usual the original poster didn't really indicate what his intended use for the car will be. Is it a race only drag car, or a weekend cruiser, or a daily driver.
As others have stated, 3" will be very loud inside the car. And in my opinion is overkill. But if your just racing who cares how loud it is. If its a driver or a cruiser, the loud pipes can get old very quickly.
I read an article a couple years ago and i'll try to relay what it said even though I may be using the wrong scientific terms. But basically what its said was the by the time the exhaust gets through the mufflers, a large portion of the heat energy has been disapated, or maybe it was back pressure, anyway, it stated that you could do like 3" pipes from the headers to the mufflers, and then go 2.5" from the muffers out the back tailpipes and you wouldn't really be creating any extra back pressure by having the smaller tailpipes. But the car would be quieter with the smaller tailpipes. Wish I could find the article, I'm sure its explains it better than I did.
Anyway, I would stick with 2.5" pipes if the car sees any amount of street use, just to keep the noise down.
Good luck
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: MileHighDart]
#1398713
03/07/13 11:02 PM
03/07/13 11:02 PM
|
Joined: Feb 2003
Posts: 1,306 Laveen, Arizona
GTSDart340
OP
pro stock
|
OP
pro stock
Joined: Feb 2003
Posts: 1,306
Laveen, Arizona
|
Its going to be a street car, but not a daily driver.
1949 International KB-2 "Mater" - 302/T5
1968 Dodge Dart GTS "The Drat" - 340/727
2006 Dodge Magnum R/T - Hemi
2016 Dodge Durango Limited - 3.6
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: GTSDart340]
#1398714
03/08/13 12:47 AM
03/08/13 12:47 AM
|
Joined: Aug 2003
Posts: 848 Avondale AZ
Prodart440
super stock
|
super stock
Joined: Aug 2003
Posts: 848
Avondale AZ
|
I see you came to ask the professionals. I think 2.5" would be plenty. You will be fast enough, and light enough, to beat all your brothers and their GM cars.
Aaron
68 Roadrunner 383/AT 69 Dart GT Conv. 383/AT 05 Dodge Ram 4x4 Cummins 06 GoManGo R/T Daytona #757 68 Coronet 440
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: GTSDart340]
#1398715
03/08/13 01:00 AM
03/08/13 01:00 AM
|
Joined: Jan 2003
Posts: 5,330 Land 'O Lakes
RoadRunnerLuva
master
|
master
Joined: Jan 2003
Posts: 5,330
Land 'O Lakes
|
I went through this same thing last summer with my Duster! I have a mild 360 currently as well. I debated and went back and forth for weeks... deciding on what to do. Since mine is just a weekend summer cruiser (car show/cruise nite/ice cream runner type Mopar)...I went with a header back Jegs(Pypes) full 2-1/2 inch kit which is a nice kit IMO. All aluminized mandrel pre-bent tubing with (optional H-pipe) which I got. I wanted to go the full exhaust route, with 2.5" stainless steel tips. I had a local muffler shop do the work,because I wanted everything welded properly. They had an easy time until they assembled the 2.5" tailpipes next to the factory gas tank. It took them quite awhile to get the fitment just right on the pass. side pipe...between the tank and leaf spring. IT'S TIGHT THERE! The system turned out great though,sounds awesome with Flowmaster 2 chambers. So....if you are thinking of going with a 3 inch system out the back...think twice about the gas tank issue! Good Luck!
Last edited by RoadRunnerLuva; 03/08/13 11:13 AM.
Plymouth Makes It!
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: RoadRunnerLuva]
#1398716
03/08/13 04:29 PM
03/08/13 04:29 PM
|
Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
top fuel
|
top fuel
Joined: Jul 2007
Posts: 1,682
Philadelphia
|
Quote:
I went through this same thing last summer with my Duster! I have a mild 360 currently as well. I debated and went back and forth for weeks... deciding on what to do. Since mine is just a weekend summer cruiser (car show/cruise nite/ice cream runner type Mopar)...I went with a header back Jegs(Pypes) full 2-1/2 inch kit which is a nice kit IMO.
All aluminized mandrel pre-bent tubing with (optional H-pipe) which I got.
I wanted to go the full exhaust route, with 2.5" stainless steel tips. I had a local muffler shop do the work,because I wanted everything welded properly. They had an easy time until they assembled the 2.5" tailpipes next to the factory gas tank. It took them quite awhile to get the fitment just right on the pass. side pipe...between the tank and leaf spring. IT'S TIGHT THERE! The system turned out great though,sounds awesome with Flowmaster 2 chambers.
So....if you are thinking of going with a 3 inch system out the back...think twice about the gas tank issue! Good Luck!
Yep I put that kit on my 73 swinger- the passenger side over-axle isn't quite right. I had to do some surgery to get it right. Still was cheaper and easier than going to the local shop with a non-mandril bender that's going to try and sell you flowmaster 40s!
|
|
|
Re: 2.5 or 3" exhaust? 68 dart 360
[Re: MileHighDart]
#1398717
03/08/13 04:47 PM
03/08/13 04:47 PM
|
Joined: Dec 2006
Posts: 3,533 Indiana
Fury Fan
master
|
master
Joined: Dec 2006
Posts: 3,533
Indiana
|
Quote:
I read an article a couple years ago and i'll try to relay what it said even though I may be using the wrong scientific terms. But basically what its said was the by the time the exhaust gets through the mufflers, a large portion of the heat energy has been disapated, or maybe it was back pressure, anyway, it stated that you could do like 3" pipes from the headers to the mufflers, and then go 2.5" from the muffers out the back tailpipes and you wouldn't really be creating any extra back pressure by having the smaller tailpipes. But the car would be quieter with the smaller tailpipes. Wish I could find the article, I'm sure its explains it better than I did.
Anyway, I would stick with 2.5" pipes if the car sees any amount of street use, just to keep the noise down.
Good luck
Have read similar articles and his summation is not far off.
Tailpipes are an oft-overlooked key in noise control. Size and location of the turndown are key.
|
|
|
|
|