Flowmaster drone - Chevelle Tech
Headers and Exhaust Discussion related to Exhaust systems and headers.

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post #1 of 46 (permalink) Old Feb 7th, 20, 1:20 AM Thread Starter
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Flowmaster drone

I have 50 series Flowmaster on my 66 and I have a pretty annoying drone at certain cruise RPMís. Iím assuming, right or wrong, that the drone is resonating from the body of the muffler as opposed to out the tail pipe.
If this is the case would the shield they offer help? Has anyone ever used them? Has anyone ever wrapped the mufflers with high temp wrap?
Or should I just bite the bullet and get new mufflers after only 300 miles?

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post #2 of 46 (permalink) Old Feb 7th, 20, 7:33 AM
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Do you have X pipe ?
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post #3 of 46 (permalink) Old Feb 7th, 20, 9:14 AM
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Re: Flowmaster drone

tHE x HELPS SMOOTH OUT THE PULSES, THEREFORE THE TONE, THEREFORE THE DRONE. ( WHOOPS SORRY FOR CAPS)

however, i believe you are experiencing the drone that is typical of chambered mufflers. I never liked it myself. GO staight thru - much different sound. Magnaflow, Walker/Dynomax, etc.
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post #4 of 46 (permalink) Old Feb 7th, 20, 9:41 AM
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Do you have any sound deadening material other than factory on the interior of your car?
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post #5 of 46 (permalink) Old Feb 8th, 20, 1:26 AM Thread Starter
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Re: Flowmaster drone

In addition to the 50 Series Flowmaster I have a 2.5Ē Pypes SS system all the way to the rear bumper. It includes an ďXĒ pipe. I also have catalytic converters on the down pipes.
The floors, doors and quarters all have Dynomat. The carpet has jute under it too. The divider between the rear seat and trunk has the divider board and jute but Iím going to seal that up better with MLV.
Iíve read about some bandaids to fix it but Iím thinking the cleaner solution is just change the mufflers. I can sell the Flowmasters because they only have about 300 miles on them and look new.
Whatís a good no-drone muffler?

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post #6 of 46 (permalink) Old Feb 8th, 20, 7:36 AM
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Quote:
Originally Posted by 67_LS1 View Post
In addition to the 50 Series Flowmaster I have a 2.5” Pypes SS system all the way to the rear bumper. It includes an “X” pipe. I also have catalytic converters on the down pipes.
The floors, doors and quarters all have Dynomat. The carpet has jute under it too. The divider between the rear seat and trunk has the divider board and jute but I’m going to seal that up better with MLV.
I’ve read about some bandaids to fix it but I’m thinking the cleaner solution is just change the mufflers. I can sell the Flowmasters because they only have about 300 miles on them and look new.
What’s a good no-drone muffler?
I have your Pypes system, no cats but with Pypes Super Street ? Mufflers. Very little drone. I absolutely love it !

Why cats ???
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post #7 of 46 (permalink) Old Feb 8th, 20, 8:38 AM
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post #8 of 46 (permalink) Old Feb 8th, 20, 8:53 AM
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Re: Flowmaster drone

Cats required in Cali ? like already said get some straight through mufflers, I have pypes 3" X system to the bumper with violators with a 454 and isn't as loud and droney as my 96 318 ram with true duels and FM 40's, I really hated those mufflers but they were new in the box at a shop my friend took over and I got them for next to nothing, still hated them


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post #9 of 46 (permalink) Old Feb 8th, 20, 11:00 AM Thread Starter
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Re: Flowmaster drone

The cats are not required in California. You only have to smog check cars newer than 1975.
The cats are on there because it was easier. The down pipes line up perfectly with the humps in the transmission crossmember and the ECM needs to see a difference from the first 02 sensor to the second. Otherwise it sets a code and turns on the MIL. I had cats on my 67 conv. too.
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post #10 of 46 (permalink) Old Feb 8th, 20, 11:32 AM
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Re: Flowmaster drone

Throw them out and get the largest (long) case dynomax turbo. They will always drone x H wont stop it

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post #11 of 46 (permalink) Old Feb 8th, 20, 12:11 PM
 
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Re: Flowmaster drone

Quote:
Originally Posted by 67_LS1 View Post
I have 50 series Flowmaster on my 66 and I have a pretty annoying drone at certain cruise RPMís. Iím assuming, right or wrong, that the drone is resonating from the body of the muffler as opposed to out the tail pipe.
If this is the case would the shield they offer help? Has anyone ever used them? Has anyone ever wrapped the mufflers with high temp wrap?
Or should I just bite the bullet and get new mufflers after only 300 miles?
Which FM 50 series do you have? There are 2, Delta and Super. The Super is the quieter of the two, and claims to reasonably control drone. The 70 series is a larger case Super 50 and is that much quieter. I have personally spent time in two cars with Super 50's, and interior resonance was not bad at all. Drone is most prominent in the 1800-2300 RPM range however, so final axle ratio plays a big part too.
One muffler that seems to eliminate drone pretty well is the Dynomax Super Turbo, especially the 20" version- part #17749. They flow very well and are fairly quiet, even on radical engines. You'll find some helpful information here- https://classicmusclecarexhaust.com/i/exhaust-101 to help you find the muffler that's right for you.
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post #12 of 46 (permalink) Old Feb 8th, 20, 12:43 PM Thread Starter
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Re: Flowmaster drone

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Originally Posted by cuisinartvette View Post
Throw them out and get the largest (long) case dynomax turbo. They will always drone x H wont stop it
I already have the ďXĒ pipe but Iím thinking changing mufflers is the way to go.

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post #13 of 46 (permalink) Old Feb 8th, 20, 12:51 PM
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Re: Flowmaster drone

Quote:
Originally Posted by 67_LS1 View Post
The cats are not required in California. You only have to smog check cars newer than 1975.
The cats are on there because it was easier. The down pipes line up perfectly with the humps in the transmission crossmember and the ECM needs to see a difference from the first 02 sensor to the second. Otherwise it sets a code and turns on the MIL. I had cats on my 67 conv. too.
I'm thinking that I must be all wrong, and that I'm seeing an optical illusion, but I have to ask you this.....

why does it look like you're using black iron plumbing pipe for exhaust pieces in one of the pics you've posted? LOL...that black pipe in the pic in post #9 looks like it has a wall thickness much too thick to be using for exhaust. Please tell me that I'm all wrong, or that I'm missing something obvious, or that it's merely an optical illusion in that pic, and that you're not using plumbing pipe for an exhaust piece. Sorry, but I just had to ask
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post #14 of 46 (permalink) Old Feb 8th, 20, 12:56 PM
 
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Re: Flowmaster drone

As far as noise is concerned, an X or H pipe will not reduce drone, only the dB level. Drone needs to be dealt with at the muffler level. 20" Dynomax Super Turbo's are probably going to get you what you want. https://classicmusclecarexhaust.com/...turbo-mufflers
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post #15 of 46 (permalink) Old Feb 8th, 20, 1:00 PM Thread Starter
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Re: Flowmaster drone

Quote:
Originally Posted by BillyGman View Post
I'm thinking that I must be all wrong, and that I'm seeing an optical illusion, but I have to ask you this.....

why does it look like you're using black iron plumbing pipe for exhaust pieces in one of the pics you've posted? LOL...that black pipe in the pic in post #9 looks like it has a wall thickness much too thick to be using for exhaust. Please tell me that I'm all wrong, or that I'm missing something obvious, or that it's merely an optical illusion in that pic, and that you're not using plumbing pipe for an exhaust piece. Sorry, but I just had to ask
Itís even worse than you think! Thatís PVC! But I was just using it for a pic so I could explain it to a supplier.
Rest assured that there is no PVC or black iron pipe in my exhaust system.

PS- you also would have hated my wooden motor mounts that I built before copying them in steel
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