Hi Gang,

I have a 1966 Dodge Dart GT /6 225. I keep finding info in the forums on folks who have upgraded their exhaust system and I would like to do the same. There is a lack of comprehensive info on what this actually entails. Can you help answer the following questions:

1. Can I use my existing stock exhaust manifold, regardless of the diameter of the bottom opening in the manifold? Also, did the size of the opening ever vary by year?

2. Do I want to go 2.25" all the way from the exhaust manifold to the bumper?

3. If so, what models/years should I look for if I have to go to the bone yard to get the pipe segment from the exhaust manifold to the muffler?


Thanks as usual,

Tom

1. yes, use it unless it's cracked. no, the choke pocket changed, and newer manifolds are stronger to resist cracking, but don't vary in size much.

2. Yes, or close to it. Think "free flowing"

3. Good luck finding anything at a bone yard that's better than the stock size. Someone else can point out years that interchange, but I would keep in mind that it would be a very lucky find.

_________________
1980 Aspen 225 super six

Hey, since you're in Portland I have to add my $.02. I got my 2.25 exhaust done for my '63 Dart GT 225 /6 at Spains Auto Repair in Portland(on the border with Clackamas). Larry and Ab Spain are pretty cool mopar type people. Larry charged me $100 for the complete pipe from the manifold to the exhaust tip, including a turbo muffler. That might have been a friend price since I've had them do a bunch of work over the years, but give them a call. Spain's is located off of I-205 on the overpass just south of the Johnson Creek exit.
Also, I find the 2.25/turbo muffler combo to have a bit of resonance going down the freeway. Cool for a hot rod maybe but I would go 2 inch or a different muffler if I were doing a stocker.

Have Fun, Mark

p.s. Oh yeah, using your stock manifold works just fine. The larger head pipe gives a bit of wiggle room so that none of the manifolds outlet is blocked. If you have lots of time and too much energy you could enlarge the manifold opening a bit (maybe with a hone) but I dont know if its worthwhile.

1) Q1: Yes. Q2: Not enough to worry about trying to find a 'better' one (unless your existing one is cracked as S6RT said)

2) Yes.

3) Have a muffler shop bend a whole new system. As Aloxite pointed out it is relatively inexpensive.

-S/6

The 2 1/4 inch exhaust came on F-bodies, trucks, and vans (super six years). There was never a factory A-body 2 1/4 inch exhaust. A header pipe form a f body or truck or van will not clear the k-frame on an a-body, so you are out of luck trying to find one that will fit on a boneyard car (unless you find a junked A-body that already had a 2 1/4 inch exhaust line).

go 2 1/4 inches all the way back, and get a good flowing muffler.

Reed, I may be mistaken, but I thought the Feather Duster and Dart Lites came with the factory 2 1/4 inch exhaust? Not that it'll be easy to find either of those in a junkyard still relatively intact...


Also, SCE makes a copper collector gasket that should fit with the 2 1/4 exhaust. Just in case you have problems finding someplace that sells the larger factory type gasket, like I did.

[url]Summitracing.com[/url] Part number - SCE-4225

_________________
Erik T.
1974 Dodge Dart Swinger - 225, A904, 8 1/4, B5 Blue w/ White Vinyl
1982 Chrysler Cordoba - 318 Lean Burn, A999, 7 1/4, VC4 Glacier Blue w/ Dark Blue Vinyl

The Felpro gasket set for the intake/exhaust manifolds has a 2" and 2 1/4" exhaust gasket included. The Dart Lite and Feather Duster had a 2 /14" head and intermediate pipe and 1 7/8" tail pipe. Replacements pipes can be found in the Maremount Catalog available at your local Shucks.

I have never seen a Super Six setup with a 2 1/4" head pipe and I have removed 3 and inspected several others.

Thanks for all the help everyone, especially Marc in Vancouver. Took it to Spains and got the car back today. What a difference upsizing makes.

Thanks again,

Tom

So what differences did this make? Please elaborate.

When I tried a 2-1/4" pipe all I got was a lot of resonance at highway cruise speed and a headache.

A bigger pipe right off the exhaust manifold really helps to improve the flow on a stock SL6 just because doing that takes a big restriction "step" out of the system. (the manifold outlet is at 2 inch, most stock head pipes are at 1 3/4 so there is a "neck-down" right where the pipe connects)

As a general rule, the front part of the exhaust system is the most important becase the exhaust gas takes-up the most space when it is the hottest. (flame takes-up more space than heat / smoke)

A good system coming off a stock cast iron exhaust manifold is to start with the 2 1/4 pipe and get down under the car. (3-4 feet) At that point you can continue with the 2 1/4 or step down to 2 inch to allow a little more clearance going under the trans. cross member "tight spot".

Once at the muffler you need to decide how loud you want the car, I find that turbo mufflers are loud. Instead use a reverse flow type muffler with at least a 2 inch inlet size. Dynomax make a good one. Once you get through the muffler it is a "free ride" out the tailpipe, the exhause gas has cooled to the point where it does not have a lot of volume. If you want noise control then step down to 1 3/4 for the tailpipe, doing this really helps to lower the noise level and makes routing / hanging the tail pipe easer.

This is what I use on a stock SL6 engine. If the engine has more "flow" (performance) then a bigger system is in order, with better flow at the front, right off the cylinder head.
DD