I am looking for a little input on an exhaust system. I have the Dutra Duals. (not installed yet). Lets also pretend to have a 300HP Slant (260ci) that doesn't rev over 5500 RPM. I looking for a clean look under the car. I also don't want a lot of noise. My current muffler resonates inside the car at cruise speed. (single exhaust right now) I'd like to be able to talk on the phone at light acel and cruise. However I don't want to choke this engine just to keep it quiter. I would like one pipe to exit the rear.
My idea is to come off each cast manifold with a 2" pipe going back to the stock mufflers location and use some type of 2 into 1 high flow but quiter muffler. Then from this muffler one 3" pipe out the back with a nice chrome tip.
Keep in mind this is a torque motor. I don't know much about the X or H pipes and they might not even apply here. I've heard that more torque can be had by combining the pipes sooner. Is this true? Is using a 2 into 1 muffler like using a crossover pipe?
Your thought and ideas are welcomed

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

3" pipe is excessive; use 2¼".

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan I seen a 66 Dart 273 four barrel that had dual exhust exiting out the back together on the driver side in to a chrome tailpipe about 2 inches tall and 4 inches wide. I was 16 at the time but i remember the driver laying two good black stripes and the sound . Was this a option or standard for the 273 four barrel . Thanks Ron Parker








It Aint Over Until I Win

You saw the back end of the A-body 273-4bbl resonator. It was a 4" diameter round muffler-type resonator, but instead of terminating in an end cap and pipe, the sidewalls of the resonator were brought rearward and squared, then chromed. Got a spare $320? You can buy
a brand new one!

Pipe size leading into the resonator was 1-7/8" or 2".

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan have you got one or do i have to order one and am right that both tailpipes go in to this. This is what i want on my 340 65 Barracuda. Thanks Ron Parker











It Aint Over Until I Win

Nope...click the link in the post above, that goes directly to the source.
There is no "both tailpipes". The '65-'67 273-4bbl cars didn't have duals.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Ok Thanks Dan Ron Parker













It Aint Over Until I Win

Brennan,

IMHO the best way to do your exhaust is to bring the 2- 2" pipes off your exh manifold into a Y-pipe just past the firewall underneath .Then off the Y go 2 1/4"-2 1/2" single pipe into and out of your muffler,over the axle to the rear with a nice turndown.

Hope this helps.

JZ

I have run 2-1/2" on my red car before with a flowmaster. Opening the dump cap would pick the car up a tenth.

I have a setup now that goes from 2-1/4" at the header to 2-1/2" and then to 3". I took it off and ran the header open with an extension and saw no gain.

For performance with a high horsepower motor, you want as big a system as you can fit under the car.

On a relatively stock motor anything over 2-1/4" is a waste of money.

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Official Cookie and Mater Tormentor.

Not sure that's always the case. Seems to me Cameron Tilley's done extensive experimentation with high-HP slant-6 exhaust systems, and while I don't remember his specific recommendations (search Tilley AND exhaust* on here) I also don't remember his advocating "as big as possible".

I could be wrong.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

All I know is what my on-track testing has shown.

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Official Cookie and Mater Tormentor.

Keeping in mind the comments mde about "quiet", if you get bigger than 2" from the muffler on back, it can get pretty "resonant" in an uncomfortable way at around 2200 RPM. A standing wave gets set up in the pipe that length and size, regardless of the muffler you use. The only way around that is to put a resonator of some sort on the end.
Sam

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You are correct, the slant six does not need need a cross over, it fires even as does all four and six cylinder engines. How you kill the noise is simple. run the same diameter tube from the manifold all the way out the rear of the car. do not terminate before the rear axle. Use 2 inch I.D. for what you are talking about. Use a turbo style muffler but use the longest muffler body that fits under the car. don't use a 12 inch long muffler if a 20 inch muffler fits. The shorty gives you the hotrod sound because there is no place for the noise to go but out the tail pipe. The larger muffler gives a better volume to disperse the pulses that create the sound. remember glass packs, CHERRY BOMBS?? If you wanted to wake the whole neighborhood, you used the 12 inch Bad Boys, but if you wanted that real sexy deep throat sound, you used the 36 inch pukers and ran a resonator on the tip that was usually another cherry bomb, 12 inches long, and was the next diameter in size. 2 inch exhaust, 2.25 inch resonator. You could sneak home with that set-up and it wouldn't bark until you really stood on the LOUD pedal. As I recall, Cherry bombs are making a come-back. The last time I ran Glass Packs I ran a 36 inch, 2.25 inch I.D. Primary Muffler, with a 12 inch, 2.25 I.D. for a resonator. I told the muffler installer to use 2 inch tube and to expand the ends to fit inside the 2.25 Mufflers. This sounded really healthy going through town, but not LOUD. going down the freeway you couldn't hear it with the windows rolled up. And I always go all the way out the rear and use a straight cut, chrome tip, with a rounded end, so no one cuts their leg if they get too close. On my Turbo Charged Build-up I used exactly the same set-up, but went to 2.50 and 3.00 inch diameters respectively. The Muffler Installers think I am nuts but that is alright. I am the one who gets the headache when it is just to damn loud.