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Exhaust "drone" sound

D

Dave P

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Hi all,
Have a 66 Belvedere 273 V8 auto. Previous owner spent some money on a
nice full dual exhaust using Flowmasters ( unknown at this point which ones ).
Anyway, the droning sounds at what's basically everyday driving speeds is
very unpleasant to my ears.
Before I cut em off and redo the whole system does anybody know if a H pipe or
X pipe setup will alter the sound much. I don't mind a rumble at idle or
being louder at full throttle but the sound cruising.. well. it just sucks!
Thanks
Dave
 
Flowmasters ( if they are real ones, and not knockoffs) have the part number engraved on the outlet panel. Should tell you what series.
You could put an h-pipe (easy) or an x-pipe (hard) in, but i dont think either will help much with the drone. Flowmasters are famous for it, and lots of people have used h's and x's, if they fixed the drone, flowmaster wouldnt have that rep.
If you have the room, you could try resonators in the tailpipes. But they are sometimes as much as the mufflers.
I think your best solution would be to cut them off, and replace with a turbo style.
 
Ah yes, dronemasters! Welcome to the club. You’ll get input on a variety of different things from the group here. Remember that each car / engine is a bit different. Just changes in displacement will alter this.

basics: change mufflers to something inherently quieter, larger flowmasters help too (50 series). Add resonators into tailpipes. Welding in an H-pipe can help a little bit too.

not-basics: calculate and weld in helmholtz resonators (J-tube).

other stuff that really wont do much: get tailpipes past rear bumper, bigger/smaller pipes.
 
Nate S said:
Ah yes, dronemasters! Welcome to the club. You’ll get input on a variety of different things from the group here. Remember that each car / engine is a bit different. Just changes in displacement will alter this.

basics: change mufflers to something inherently quieter, larger flowmasters help too (50 series). Add resonators into tailpipes. Welding in an H-pipe can help a little bit too.

not-basics: calculate and weld in helmholtz resonators (J-tube).

other stuff that really wont do much: get tailpipes past rear bumper, bigger/smaller pipes.
Click to expand...
Agree with the bigger 50 series. I am using a pair, but they are huge! No drone, but they will be difficult to get under the car, and in my opinion, expensive.
The Helmholtz resonators are the most elegant (and comment-worthy) solution, but they require some experimentation to get exactly right.
 
The Walker Dynomax is my muffler of choice. Nice rumble and no droning noise.
 
Thanks for the reply's.
They're Flowmasters, the numbers are on them but I didn't look that close.
From my eyeball size recollection I'd guess them to be a 50 series.
Based on the comments I think cutting them out and finding some different
mufflers will be the direction to go. The tuned J pipes look valid but I'm not
married to what's under the car so probably just ditch the Flowmasters and
be done. Maybe clamp these to start with and see what the sound is like.
Dave
 
No offense intended, but i doubt you have the 50 seies big block mufflers on your car. I think you prbably have 40s, or some variety of 44.
My 50s are 5x12, 22" long case, 28"overall.
Typical turbo has a 13" case, 4x9, 19 overall.


Whoops. According to summit, there are 50s with a 4x9 1/4 case, but 17" long case, four inches longer than a normal 40/44 case.
 
No worries, I didn't look that close. Going to be changing the headlight switch tonight and
I'll crawl under after and get the dims and numbers off them.
Dave
 
I have FM's with an X pipe, 3", and headers; I'm in the process of dumping the mufflers and right now kind of set on Accurate Exhaust (drop down to 2.5 inlet/outlet) after looking at a dozen different mufflers to choose from. There are some that sound good (pun also intended) but looks as though the AE's will assure I don't end up with something too close to what I have.
 
Ok they're Flowmaster part number 842451 about 17in long 2.25 in tubes.
I'm going to find a print with offset and total length and try to find something a bit
longer. They're welded on so I figure to loose a bit of pipe on both ends taking them off.
Thanks for the ideas.
Dave
 
Thats close to the quietest muffler flowmaster makes. In my opinion, you will need a pretty big triple pass muffler to be quieter.
You could try a walker dynomax super turbo, 17747. Same in/out and pipe size as your flows, case is 20", oal 25.5. Good reputation for quiet flow. Might be too quiet.
 
Last edited:
I was always happy with Magnaflow. Several cars and none had the drone.
 
IMP 33,
Thanks for the suggestion, at first look it seems the Walkers would fit. Got to get it lifted and get under there and
check the space but thinking your recommendation would be good.
Dave
 
I had FlowMaster 40s on mine for years
I hated the drone but with the 3.91 gear I didnt get on the highway much anyway and I just tolerated it
When we built and installed the latest engine we were making a lot more power with a bigger tube header so I took it down to the local Muffler shop
They created an new system for me but He talked me into going with the new FlowFX mufflers instead of the 40s or 50s
WOW what a difference
no more drone
and on the bright side the new FLowFX design is one of the least HP sucking mufflers made
watch the Engine Masters muffler test

Take a look at the FlowFX mufflers
I love mine
 
On this topic, just had the Accurate hemi mufflers installed and pretty happy with those; certainly quieter, though quite not as much as I was expecting. I didn't want to get too quiet anyway. The headers, 3" and X might be a reason. I'll be selling my FM 50's as they have all of about 3k on them. They sounded neat, many compliments - just louder than I need at a my age.
 
I just ordered the Walker Dynomax suggested above.
It'll be at least a couple of weeks before I get time to install
them.
Will post up thoughts when done.
Dave
 
You well be pleased and sound should be pleasant!
 
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