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Exhaust opinions / Mandrel bent 2.5 or 3" / Input?
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Author:  Backtobasics [ Fri Aug 15, 2008 8:51 am ]
Post subject:  Exhaust opinions / Mandrel bent 2.5 or 3" / Input?
Next modification on my Dart Lite, is exhaust.

Currently has single system, that Y off into 2 or 2.5 dual, 12" glasspacks, and crushed tailpipes that rattle and bang on everything.

My local customer will bend me 2.5 or 3" (these are the only 2 sizes they can mandrel bend). They will come off the manifold with 2-2.5 and step up at the bellhousing under the car, with a flange so I can remove to fab turbo tubing, and re- install to drive as needed or wanted.

If I go 2.5 I can get the muffler and tip free (vendor rep). :)
If I go 3" I have to buy the muffler and tip, or I can have it turned down just behind the bumper for stealth look.

I know both sizes are overkill for a N/A /6. However, this car will sprout a turbo over the winter. (Grand National Turbo, Front mount intercooler) I think the 2.5 would work since it is mandrel bent would be OK for the turbo system, but I am leaning more towards the 3" system.
Opinions? Input from some of the turbo guys?
Author:  sandy in BC [ Fri Aug 15, 2008 9:15 am ]
Post subject: 
Two point five!

The 3" single will just hurt you.

Off a stock manifold you really cant go above 2 anaquarter.....
Author:  ceej [ Fri Aug 15, 2008 9:37 am ]
Post subject: 
After you get to the muffler, reduce the size. There is no down-side to doing so. The gasses have cooled by that time, and you'll want to keep velocity up to help dry the system.

Using a 2.5" Tailpipe won't promote evacuation of water from the system, and will accelerate deterioration of your muffler and exhaust pipe. Combustion byproducts combined with water will make acids, and shortly thereafter, holes.

Even after running for quite a while my 2-1/4" System blows water out the tailpipe during hard acceleration. Track officials don't like that, nor does the driver of the car staging next. :?

There would have been no reduction in power staying with the 1-7/8" Tailpipe with my particular NA build.

I'd think 2" would be more than adequate for a turbo tailpipe.

2¢

CJ
Author:  Aggressive Ted [ Fri Aug 15, 2008 8:18 pm ]
Post subject: 
The guy that bent mine up did a real smooth job and the pipe is not crushed and wrinkled like some you see. He took his time on the bends using very thick top grade tube to start with . I went 2.25" all the way since the stock exhaust flange limits you to 2.25". You could do a slip fit tube from the exhaust manifold flange using 2.25" for a few inches and then 2.5" on the bend all the way back...just a thought... :D

Your going to modify the front pipe anyway.....
Author:  SlantSixDan [ Fri Aug 15, 2008 11:22 pm ]
Post subject: 
2½" and 3" are both too large. Use 2¼".
Author:  Backtobasics [ Sat Aug 16, 2008 5:31 pm ]
Post subject: 
2.25 seems perfect for natural aspirated, but this is going to be built to be compatible with the turbo, so I do not have to have exhaust run twice?
Author:  Aggressive Ted [ Sat Aug 16, 2008 9:59 pm ]
Post subject: 
Go with 2.5" and use 2.25" for the first foot or so since you going to replace it anyway.
Or find someone that has super thick 2.25" tubing so the bends don't wrinkle like thin wall tubing. My system is pretty quiet for running a Flow Master 40 muffler.
Author:  turbo66valiant [ Sun Aug 17, 2008 6:47 pm ]
Post subject: 
Contrary to popular opinion, I would go with the 3" and a turn down (or tip). I always build for the future and if your going to build a turbo set-up, 3" it is. If the Dodge Shelby cars gain with a mandrel 3" then all the better for a bigger cube slant. Keep the pipe to the turbo around 2.5 but turbo back a 3". Later
Author:  Backtobasics [ Sun Aug 17, 2008 7:17 pm ]
Post subject: 
This is absolutely a system for the future. I am running the exhaust now, before the twins get here. I am not going to re-run the system once I install the turbo. I am having the system flanged right at the bellhousing so I can add the turbo downpipe to the existing system.
Author:  Matt Cramer [ Wed Aug 20, 2008 7:10 pm ]
Post subject: 
Go for 3" all the way, and I'd go with a straight through rather than a chambered (like a Flowmaster) type muffler. A turbo car can't have too big an exhaust - we are using a 3" exhaust on a little bitty Miata at work, and it hasn't killed off the miniscule low end torque that car has. I'm seriously thinking about what it would take to run a 4" exhaust on my Dart.
Author:  Dart270 [ Thu Aug 21, 2008 7:50 am ]
Post subject: 
For the turbo, yep, go 3". Cameron Tilley as either 3" or 3.5" on his turbo car and said it could use more.

Lou
Author:  turbo66valiant [ Thu Aug 21, 2008 4:05 pm ]
Post subject: 
What I use are the 3" Flowmaster U-weld pre-bent mandrel kits and cut and weld them. I'm a Silverline wholesaler so I just use my own straight thru stainless mufflers. When I was putting my car together, I checked a couple tailpipes from diesel kits and found the 4" 99-03 7.3 Ford would work the best with only a couple cut and welds. For sure, my next system will be a 4". I would say 3" street and 4" race.
PS
If anyone wants some Stainless mufflers and tips, I can get them for any of you slanters at jobber price. Silverline is made by ANSA.
Goodluck!
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