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Straight through mufflers

General engine tech -- Drag Racing to Circle Track

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ptuomov
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Re: Straight through mufflers

Post by ptuomov » Mon Jun 29, 2020 5:01 pm

tjs44 wrote:
Mon Jun 29, 2020 3:03 pm
I dont care if i loose 50 HP if I can kill the drone.Car operates 99.9% of the time from off idle to 2500 max.Cruise either in 4th on the street of 5th on the freeway is at 2000.Tom
In my opinion, a key to eliminating the drone is to have many mufflers, many pipe sections of different length, and a crossover or two. None of these measures in my opinion mean that one has to increase back pressure or lose any power.

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Re: Straight through mufflers

Post by pdq67 » Mon Jun 29, 2020 9:18 pm

Travis,

Might butt end to end a couple or even three WDT smooth perforated inner pipe real glass packs to help quiet her down. And I did this way back when I had my 409 "W" engine in my car.

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Re: Straight through mufflers

Post by SpeierRacingHeads » Mon Jun 29, 2020 10:02 pm

Has anyone ever tried a Thrush Rattler?
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Re: Straight through mufflers

Post by econo racer » Tue Jun 30, 2020 5:04 am

I own a muffler shop and I can tell you this. In your case I would adapt down to a 3 inch muffler with 2-3 inch tailpipes using the Dynomax super turbo muffler. It will sound a little quiter but more grown man sound and it breathes very well. I am a very big fan of there mufflers. I have uncapped my car at the track and it ran no faster maybe.04 for weight. Try it you will like it. :D There quality too.

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Re: Straight through mufflers

Post by ptuomov » Tue Jun 30, 2020 7:58 am

econo racer wrote:
Tue Jun 30, 2020 5:04 am
I own a muffler shop and I can tell you this. In your case I would adapt down to a 3 inch muffler with 2-3 inch tailpipes using the Dynomax super turbo muffler. It will sound a little quiter but more grown man sound and it breathes very well. I am a very big fan of there mufflers. I have uncapped my car at the track and it ran no faster maybe.04 for weight. Try it you will like it. :D There quality too.
I think that stepping down the exhaust pipe size as the exhaust gas cools makes all the sense in the world. If one looks at new factory stock performance cars, they all seem to be stepping down the pipe size from the turbine outlet to tailpipe and put the mufflers at the rear bumper area. I think that one of the main advantages is that one can have a muffler with a small pipe inlet/outlet area divided by the muffler chamber cross-sectional area, which leads to good noise suppression.

We tried to guesstimate how much the exhaust gas cools as it gets further down from the engine in this thread:
viewtopic.php?f=1&t=49628&start=45#p662407

No idea how close we got. Our final guess was that if you start with 3.5" pipe at the turbine outlet, 2.5 meters (about 8 feet) down you can go to 3" pipe while maintaining the same exhaust gas velocity. After a cross-over in a cross-plane V8, one could probably go down even more without losses.

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Re: Straight through mufflers

Post by falcongeorge » Tue Jun 30, 2020 4:24 pm

x3 on the smaller tailpipes. Same size as the collectors up to the mufflers, smaller afterwards. My experience is, no loss with smaller tailpipes, and quieter. This is what I am running on my chevy II, 3" tubes, x-pipe and Ultraflows into 2.5" tailpipes over the axle. Easier packaging, quieter and virtually no performance loss as compared to 3" tailpipes or dumped in front of the axle. Heat is energy, large surface area of big pipes dissipates that heat faster, what happens after the mufflers is probably of little consequence, within reason.

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Re: Straight through mufflers

Post by enigma57 » Thu Jul 02, 2020 2:54 am

travis wrote:
Fri Jun 26, 2020 3:31 pm
I would imagine that would get highly annoying very quickly if you drive it much.

One thing that would probably help though would be pointing the exhaust straight out the back, with the tip sticking out just a bit. I’ve noticed on mine, even with the really loud mufflers, that pointing the turn downs out from under the truck instead of pointed at the ground makes a huge difference inside the cab. The sound waves bouncing off the ground and back up under the bed gives it a really bad resonance, even when using quieter mufflers
That's been my experience as well, Travis. In my state, exhaust must exit outside the vehicle. Cannot terminate under the vehicle. Must extend past rear bumper. Or at the very least, must terminate outside the vehicle but behind the passenger compartment.

Not sure how tight they are on enforcing that now of days but having had carbon monoxide poisoning back in the '70s I am very careful about that.

Was working on a construction job running pipe about 20 ft. above the concrete floor. Don't remember a thing except for coming to. Passed out, fell off the ladder and got lucky...... Landed in a big pile of cardboard boxes filled with insulation. Was taken to hospital. They did a blood test and found high levels of carbon monoxide. My old work car at the time was a '62 Chevy and it had an exhaust leak I wasn't aware of.

I do like turndowns like the MOPAR cop cars had in the mid-'70s. An inch or two past the rear bumper, though.

Best regards,

Harry

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