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Quite muffler that doesn't kill power...

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Re: Quite muffler that doesn't kill power...

Postby jet1 » Fri Jun 29, 2012 5:53 pm

Yes simular to that for a V8. It still has a bit of a rumble but is it no way loud. Like I said it seems to get more rumble if you move the outlets closer. At 12 on center it is stupid quiet.
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Re: Quite muffler that doesn't kill power...

Postby exhausted » Sat Jun 30, 2012 2:18 pm

OK, we are talking a "Daily Driver" here, original question. In all cases I always try and use a muffler that actually routes flow from one tube, across the body ind into the out tube, ie you can not see through it! Chevrolet gave us the "turbo" muffler back in the 60's on the turbo corvairs. Basically a shorter and larger tube and less packing muffler. This kind of muffler term "Turbo" has been used by all muffler manufacturers to mean an lot of things so you have to really know what you are looking at. Any muffler but a real muffler will resonate at a certain rpm range and can be very uncomfortable. I have found these, http://www.stainlessworks.net/products/ ... flers.html, a great item and available up to 3" in and out. These are Stainless but items like this are available in steel. On a severe application where maximum power, ie street strip, I would use a see through design, but your ears will pay that price.
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Re: Quite muffler that doesn't kill power...

Postby exhausted » Sat Jun 30, 2012 2:29 pm

Forgot to add that a crossover or better yet a xpipe not only adds power but helps reduce droning and decibles at the end of the system.
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Re: Quite muffler that doesn't kill power...

Postby MODNROD » Sat Jun 30, 2012 5:14 pm

exhausted wrote:OK, we are talking a "Daily Driver" here, original question.

ie street strip, I would use a see through design, but your ears will pay that price.


That's why I mentioned the Hooker Maxflow I used, for a daily driver. They are VERY quiet at idle and cruise, and even thought they're straight thru, are quieter than the 3" triple-pass Walker superturbo I initially tried, but without losing a heap of HP.

Of course, put your foot into it, and all stealth is gone......
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Re: Quite muffler that doesn't kill power...

Postby cuisinartvette » Sat Jun 30, 2012 6:02 pm

Know its an old thread but good info

Orr89, seems the more air youre moving the more noise. At a point it may never be quiet unless you choke it some. Maybe Big Joe can comment with his experiences on this hes usually really direct.

With my old system I just took off it was fairly quiet on a 350 I had in there years ago
Typical 425hp setup with HFTcam
2.5" compression bent duals
H
2- 2.5" Hooker Super comp turbos

With the current 385 it was loud at any engine speed period with the same system. Seems too small a system produces those sharp metallic air piercing sounds that attract the men in blue even with part throttle. I bet the system couldnt support 350hp what 400 on a good day? Sometimes larger is quieter is seems other times not.

Concerned the 20" Ultras wont be quiet enough.
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Re: Quite muffler that doesn't kill power...

Postby jfalcon » Sat Jun 30, 2012 6:41 pm

Hi guys, i've got a 600hp sbf, with dual 3' hooker aero mufflers, it sounds great but it's too loud on the street, can i please have the part number to the magnaflow mufflers that you guys have used with success.The last few mufflers i have tried have been too loud or not enough flow .Magnaflow mufflers are very accessible here in oz.Thanks
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Re: Quite muffler that doesn't kill power...

Postby Warpspeed » Sat Jun 30, 2012 7:05 pm

Yeah, it's difficult, but there are some basic principles to keep in mind.

First is, your primary pipes and collector need to ideally empty into open air, or a large enclosed volume that is big enough to work like open air as far as exhaust tuning goes.
How big it needs to be depends on individual cylinder displacement, but bigger is better to prevent detuning the collector length.
The eight inch pipe across the car sounds like a very good idea, if you have a rear mounted engine.
An eight inch pipe along and under the car will work too, if you have sufficient ground clearance to do it.
This idea is not new, it is mentioned by Vizard, and Dr Morrison in his book "Scientific design of exhaust and intake systems", and by others. And it works.

This big stored gas volume does two things, it minimizes collector detuning, and it reduces low frequency exhaust pulsing, but only if this big "exhaust tank" has a restricted exit area to reduce noise.

How big the exit area needs to be depends on gas flow, which depends on power. Assume about 2.2 CFM per Hp.

You can just run a small bore exit pipe, and it will be quiet, even with no muffler, and it WILL NOT DRONE.
But that would cause far too much pressure drop at max power.

A larger bore exit pipe (or pipes) with glass packs or straight through mufflers will still be fairly quiet, because there will be much reduced low frequency pulsing, and only the harsh higher frequencies to deal with.

The very best results for a sleeper will be with mufflers fitted with exhaust flaps that close almost right up at low flow, and progressively open at higher power levels.
Note the spring loaded flaps fitted inside this muffler.

http://www.dynomax.com/images/mufflers/vt_lg.jpg

One, two, (or four!) Dynomax mufflers in parallel right at the back (depending on power level) would be ideal.
Building a quiet low back pressure exhaust is not that difficult, provided you have sufficient room, which is usually the biggest limitation.

For the turbo guys, just fit a very large pipe right to the back, and then the smallest flap type muffler that will work right at the very back. No drone, very low noise, and low back pressure flat out.

Just fitting a flap muffler right on the end of a header pipe will not work.
There ABSOLUTELY MUST be a big stored gas volume between the engine and flap type muffler to reduce low frequency pulsing for this type of muffler to work at all.

Some guys just stick a flap muffler on their car without doing anything else and say the muffler is crap.
It is still far too noisy. But if you build in sufficient exhaust volume before the muffler, they work like magic.
Last edited by Warpspeed on Sat Jun 30, 2012 7:20 pm, edited 2 times in total.
Cheers, Tony.
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Re: Quite muffler that doesn't kill power...

Postby cuisinartvette » Sat Jun 30, 2012 7:18 pm

Didnt click the link VT muffler?
Flaps tend to rattle with a large cam at idle or no?


Have heard its best to use an X AFTER the mufflers as the gases slow down anyone care to comment?
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Re: Quite muffler that doesn't kill power...

Postby Warpspeed » Sat Jun 30, 2012 7:23 pm

They certainly will rattle if placed right at the end of a collector.
Can sound worse than no muffler if used like that.

But placed right at the back of the vehicle where they are supposed to go, with sufficient exhaust volume ahead of the muffler, there will be very little exhaust pulsing, and no rattle.

X pipe allows each bank to empty through both exhaust sides.
Big volume exhaust with both sides joined does the same thing.
Cheers, Tony.
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Re: Quite muffler that doesn't kill power...

Postby wjnielsen » Mon Jul 02, 2012 9:32 am

So, how long do the spring and flap deal last in these mufflers?

Are all those parts stainless, or something else that'll live a long time?

-Bill
seduce the attractive... charm the rest
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Re: Quite muffler that doesn't kill power...

Postby Warpspeed » Mon Jul 02, 2012 6:21 pm

I had a pair on a car for around four and a half years, then sold the car.
Still working perfectly.

I guess mufflers are like batteries, clutches, tires, wiper blades, brake pads, spark plugs, fan belts, and radiator hoses.
Nothing lasts forever.
Cheers, Tony.
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Re: Quite muffler that doesn't kill power...

Postby xanadu » Tue Jul 03, 2012 1:03 am

Anyone used auger inserts, and had success.
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