Running resonators for reduced drone?

"Turbo-T"

V6 on steroids
Joined
Jan 10, 2007
Here's another topic on reducing drone from the exhaust.

Yes I know about the 3 muffler set up. But suppose you're running a straight shot exhaust 3" exhaust which drones horribly, and you installed it a year ago and don't quite have the funds to hack it off for a new one.

Couldn't you run a smooth perforated glasspack muffler as a resonator (or just run a resonator) and install it where the catalytic converter used to sit? Or even install it inline between the tail pipe end and the muffler?

Wouldn't this kill off the drone yet leave behind the true V6 sound w/o driving you nuts?
 
I run twin ultraflows on a single shot. One in place of the cat, one just in front of the rear axle. It's quieter than a single muffler system but still gets some resonance between 1800-2100 rpm. I've got a cam so it's not quite like stock but here's what it sounds like.

YouTube - MP4 0007
 
On my old T with an ATR single shot. I ran a Dynomax bullet muffler where the cat use to be. Killed a little bit of drone but not much.
 
Joe what style Dynomax did you use where the cat once was? oval? Bullet? Round?

I will share with you an experiment that I once tried...I had a 2.8 liter V6 powered truck that had a 40 series Flowmaster and a Catco converter that was inline with a 2.5 inch single exhaust and it droned. I found when i took an old glasspack muffler and shoved it in the end of the tail pipe, it actually killed off most of the drone. You could tell it was a V6 though but it wasn't obnoxious inside the cab like it were w/o the glasspack in the tail pipe.

However on a 3 inch single exhaust I don't know how well it would work, if at all. That's why I'm curious to see if anyone's tried it, before I hack up my single shot. :cool:
 
Joe what style Dynomax did you use where the cat once was? oval? Bullet? Round?

I used the round can style. You could use either stainless or regular.


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Dynomax 17296 Dynomax Ultra-Flo SS Mufflers

http://www.jegs.com/i/Dynomax/289/17223/10002/-1?parentProductId=744869
 
I run a Dynomax race bullet muffler on my Z28 to cut out the drone and rasp with longtube headers, I had one in place of the cat on my 3" single shot, but removed it to install an e-cutout. It really did cut back on drone, but I thought it made the exhaust note sound worse at higher RPM's.
 
Joe what style Dynomax did you use where the cat once was? oval? Bullet? Round?

I will share with you an experiment that I once tried...I had a 2.8 liter V6 powered truck that had a 40 series Flowmaster and a Catco converter that was inline with a 2.5 inch single exhaust and it droned. I found when i took an old glasspack muffler and shoved it in the end of the tail pipe, it actually killed off most of the drone. You could tell it was a V6 though but it wasn't obnoxious inside the cab like it were w/o the glasspack in the tail pipe.

However on a 3 inch single exhaust I don't know how well it would work, if at all. That's why I'm curious to see if anyone's tried it, before I hack up my single shot. :cool:

this is exactly what GM did on some cars right from the factory- on 2 different Caprices i had (a 305 powered 86 and a 350 powered 92) they ran a rather large for the time 2.75" single exhaust from the converter back to a big muffler before the rear axle, with a 2.5" tailpipe over the rear axle with a glasspack muffler welded in right before the turndown behind the bumper. both cars actually had a decent exhaust sound for a stocker, but neither had a drone of any kind while cruising down the road.
 
For some clarification, the Ultraflows can be had in different lengths and 13" is one of them. They are available in different diameters and outlets. Mine is a custom setup using a Jet Hot coated Kirban 3" downpipe, (no stock 4 bolt flange) going straight to a 3" Ultraflow. From there a Kenne Bell 3" single shot cat back was used with another Stainless Ultraflow right before the axle. I would imagine you could get the correct length muffer and weld in a 4 bolt flange. I know I've seen them, just can't remember what vender carries them. With this configuration, the front muffler can be removed and swap in a 3" cutout when needed.
 
in a word.......NO. Dennis Hogan tried every which way to eliminate drone with his ATR SS system. 3" Ultraflow in the cat position did NOTHING. Wrapping the entire exhaust from cylinder head to tail pipe, did NOTHING. DIfferent mufflers made some difference, but if it really cut drone it killed performance. His three muffler system is what really did the trick.

We never tried a resonator at the tail pipe location, but there really isn't much room to fit it sanely back there. Give it a try and let us know.
 
in a word.......NO. Dennis Hogan tried every which way to eliminate drone with his ATR SS system. 3" Ultraflow in the cat position did NOTHING. Wrapping the entire exhaust from cylinder head to tail pipe, did NOTHING. DIfferent mufflers made some difference, but if it really cut drone it killed performance. His three muffler system is what really did the trick.

We never tried a resonator at the tail pipe location, but there really isn't much room to fit it sanely back there. Give it a try and let us know.

Thanks, where can I see pics of the 3 muffler setup?
 
Thought I'd give everyone an update. I decided to be the guinea pig on this one.

Since the resonator should be as close to the end of the exhaust tail pipe as possible, and since there's not much room to work with on a straight shot exhaust, I found one muffler that could possibly fit.

What I ended up going with was a Jones Exhaust A4312B glass pack muffler. It sells new thru Summit racing for $23.95 at the time of this writing. Here's what it actually looks like:

IMG_8829.jpg


And here's the link to the info for it:

Jones Exhaust A4312B - Jones Glasspack Mufflers - Overview - SummitRacing.com

It's a short at 12 inches long total. Unlike most glass packs, this one does not the extending ends past the case; instead the pipe slips into the ends of the muffler.

IMG_8831.jpg


Here's the inside shots. This is a 3 inch muffler, the louvers I would guess are maybe 3/16 of an inch tall. I don't know how much power, if any this would hold back.

IMG_8830.jpg

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For trial testing purposes, I just shoved the muffler on the end of the tail pipe.

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On a permanent install on a straight shot set up, I would say this muffler would fit ok between the bend in the pipe off the axle clearance to the 45 degree outbound tail pipe...and where the bracket is welded on the end of the pipe to bolt it to the frame. (there's roughly 13 inches of pipe there to work with)

So the results...?

Well it's still loud, and you can still hear the exhaust inside the car....however this glasspack DID take off the edge of the drone some....meaning inside the car it wasn't as bad as without it. No it doesn't completely eliminate the drone, but I will say this...when the drone does kick in, and without this muffler, I can usually tell you without having to look at a tachometer, the rpms are between 1900-2100 rpms (the "drone zone")...with this glasspack on I had a hard time telling where the rpms were, because it actually quieted down the buzzing droning sounds...all that's left is the rumble of a V6.

I will say the car is more livable now with this added on, as opposed to not having it at all. I would certainly be willing to drive this car more often with this mod. However as mentioned (and I know it's been said glasspacks are restrictive due to the popped up louvers) I don't know how much performance this would choke, if any at all.

I didn't get any sound clips and I'm not so sure they would have revealed anything since the difference was so minute, but noticeable. So the verdict is in...if you want to keep your straight shot exhaust but are tired of the drone and don't mind spending under $30 and can weld this inline with the tail pipe, this muffler just might be your answer.
 
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