I started to, then broke a ring in the #6 cylinder. I will let you know after tear down and re-ringing the motor.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Interesting results on the smaller tailpipe. I went as small as 1¾" tailpipe on the '62 (with 2¼" headpipe into big Magnaflow muffler), and even installed a resonator in that tailpipe, and still couldn't get rid of the drone.
Uh…

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

Well Dan, don't know what is up with your set up. My son tells me the car is in stealth mode because it is so quiet and my wife loves it at 60 mph now. She says it is as quiet as the Imperial which is super quiet, all you here is wind noise around one window seal, no motor exhaust noise at all.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I have a 2.25" pipe from the manifold to muffler (Magnaflow XL), then a 2" pipe to the bumper on the Satellite. There is some resonence, but not much. On the 5th, its 2.5" to the muffler (a Flowmaster 40 series knock off, Flowsound) then a 2.25" pipe to the bumper. Silent at freeway speeds. You know its there at lower rpm's, but its not objectionable. The exhaust guy I've used for years has always told me to use a smaller pipe from the muffler back.

*Shrug* Magnaflows worked out the same (too noisy) for me on three different vehicles. I won't try 'em again. YMMV.

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

It worked on mine to get rid of the snarl, but I actually like the drone. Of course, my daily commute is 2.5 miles each way. If it was farther I might have a different opinion.

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If it was easy, everybody would be doing it.

So how's the mileage now? Did it go up any?

(Sorry for rezing an old thread, but I am curious also there is a relevant discussion on another forum and I'm using this thread for reference :p)

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Rob M
'80 D100 SWB stepside, S6 4-spd OD

Don't worry, this isn't like most other forums where you get yelled at for bringing up old topics. It's all still relevant when it comes to our cars. A lot of the time people will update 4 or 5 year old topics when new parts or techniques can replace the old ones.

I have a 2 1/2" exhaust all the way back with a flowmaster 40. It sounds awesome and isn't loud at all. Just a nice deep sound. I only have about 25k on my motor so I'm not sure if putting this setup on an older motor will have the same effect. Most people say there will be a drone or it'll just be down right noisy with my setup but so far it's been perfect. Doesn't matter if I'm crusing at 30 or 80.

With my "torque and mileage" build the mileage went down with the quieter set up. Traveling a minimum of 120 miles a day I check it every 3 days. The FlowMaster 40 knock off actually gets better mileage by 1.5 mpg consistently year round. The noise just gets to annoying on long trips although I am around the 27 mpg mark. I wish they built the same style muffler in a quieter version. The knock off FM 40 is a 14" case, the MagnaFlow is a 18" case and is about a 1" or so thicker and wider. I am using a 22" long 2" resonator that is about 5" in diameter next to the gas tank. The system is whisper quiet from idle on up through 4500 rpm.

I have a friend who runs a Delta 50 series and it is just a little louder than my 18" case MagnaFlow and it gets the better mileage that FlowMasters are known for. I am thinking of trying that set up next. Another set up I want to try is the Hooker Aerochamber mufflers. I have heard them and they have a nice mellow sound with no resonance at cruise. However, I haven't heard what they do in terms of mileage.

I have run traditional stock mufflers and turbos and they do nothing for mileage and all sound annoying at 2.25" diameter on the SL6.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I have a Thrush Flowmaster40-knock-off muffler on my '93 V8 truck, and everyone loves how it sounds. Not really relevant to a S6 I guess, just that it is a good muffler. However it is pretty loud on that truck too, but it is also dumping right out of the muffler in front of the axle.

27mpg is pretty good though I think? Not sure what the norm is for a fresh stock S6. I have a S6 truck I am planning a performance build for too, so this thread is interesting from that perspective too.

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Rob M
'80 D100 SWB stepside, S6 4-spd OD

I recently replaced my muffler from what I believe might of been stock on my valiant - replaced it with a cherry bomb "turbo" muffler 2" inlet / outlet - and i believe im running 1.75 exaust pipe on my relatively stock 225 - exits right before my rear axle with a little turn down.

and its just as quiet as a mouse.
I was realley dissapointed it was so quiet - I can barely hear the car running down the road. but thats good I guess since I like to listen to the radio - it does not have to be as loud to overcome a loud exaust system.

just figured id let yall know my results in the muffler thread incase some one out there was looking for a nice quiet muffler.

my future plans for exaust is to keep single - but upgrade to 2.25 or 2.50 size exaust pipe up to the muffler and then 2.25 up over the rear axle and out back by the rear bumper with a little chrome tip.
un certan of wich muffler to go with - but may try the thrush or cherry bomb welded chamber type muffler / because they are sort of cost effective vs a real flowmaster muffler.... i may not end up liking the louder exaust on my car - and go back to a quiet turbo style.

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1972 Plymouth Valiant / slant 6 auto

2-1/4" is a good bet. At 2-1/2" you will have to wrap to keep velocity and temperature up. Even so, wrapping can be beneficial for keeping the heat in the head pipe as long as possible.
This keeps velocity up, and will improve scavenging.

Ted's results are extrememly good for a '74. It's a heavy car. The best I ever got out of my '74 when running the 1 bbl was 18 combined. His 120 mile travel likely contributes to that. My longest trips were in the 30 mile one way range.

I peaked at 24 mpg with a Holley 390 Vac Secondary. I haven't beaten that again due to the application assigned the car:

Travel 1/4 mile at WOT. Idle back to the staging lanes. Repeat.



CJ

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Part of Tyrde-Browne Racing