I need a small but quiet muffler

2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
How about Flowmaster DBX mufflers? Anyone used them?

I might be able to make this one fit without cutting my floor out:


The design is not a complete straight through, instead its has perforated cones.

12514310_31986.jpg


Is there another brand that is similar?
 

Rt Jam

Greasemonkey
Mar 30, 2020
230
43
Ontario Canada


Go to the Flowmaster site. They have at least over a dozen mufflers on a chart in the order of decibels.
 
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78Delta88

Master Mechanic
May 23, 2022
300
43
SW Arizona
I was reading this last night and had to go "crack open the books"..., which any more means download a pdf, Etc...

The person that mention the empty pancake converter is on the right track. The issue as pointed out is low frequency harmonics. I studied this early 80's causes sickness, irritability, vertigo and other issues.

Past life I had a 65 ElCamino, 283, 2 speed power glide that shifted about 45. Yet driving to work back then most of the roads that I was on were posted speed..., 30 to 45. There was only one short spot where posted speed was 55, so the whole 30 min trip just droned out right at the power glide shift point. I changed exhaust to dual setup got a little better, but I would get to work with head spinning, dizzy and felt like crap.

I ended up selling the El Camino to a local body shop that wanted to restore it.

Later on I had a Granada coupe that had the same issue. I had local muffler shop change the stock single system to duals ... Trush turbo mufflers.

The sound got better, but it wasn't until I installed a Lunati .514/.514 lift cam that the problem went away. The cam change really woke that car up, got better response, better fuel economy, more power up and down the hills. And the drone went away, made it a joy to drive.

What is the CID of your engine? And what RPM is the engine running when you experience the majority of the droning?
 
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2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
What is the CID of your engine? And what RPM is the engine running when you experience the majority of the droning?
It's 242 cubes inches of inline obsolescence. I'd love to answer the second part of that but I'm not exactly sure, probably 2800-3600rpm though. I'd just swapped the cluster to one with a tach and then mangled a link mount due to running out of talent, so I haven't driven it on the street for the last week. Once I fix it I'll collect some data while driving by paying attention to the tach. Between a combination of horrible aerodynamics and massive rolling resistance the engine is always working fairly hard above about 30mph. Hence it winds up sitting somewhere in the mid-RPM range and just droning. You are correct that it is a very irritable noise/vibration and slowly drives you crazy.

I actually decided to order a high-flow cat to try splicing in first. Assuming it fits. I may have to cut the floor to get adequate space, but so be it. I looked at it more while cycling the suspension and I don't think I can actually run the pipe out the back, there just isn't space past the leaf spring shackle, but I can turn it a bit and dump it, which might help too as it should direct the pressure pulses away from the floor/body. I don't know.

I did spend a whole day (6 hours of actual driving) in it on the trail and it's totally not annoying as long as you're doing technical stuff. It's going to be unbearable for snow wheeling though, as that normally involves holding 50-75% throttle for hours on end. Nobody took any usable video of me (bunch of boomers can't figure out how to do much more than make a phone call with a smart phone, what can I say), but I do have terrible knock-off GoPro footage where you can't actually hear my exhaust, but hey, watch it if you want, or don't.

 
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78Delta88

Master Mechanic
May 23, 2022
300
43
SW Arizona
It's 242 cubes inches of inline obsolescence. I'd love to answer the second part of that but I'm not exactly sure, probably 2800-3600rpm though. I'd just swapped the cluster to one with a tach and then mangled a link mount due to running out of talent, so I haven't driven it on the street for the last week. Once I fix it I'll collect some data while driving by paying attention to the tach. Between a combination of horrible aerodynamics and massive rolling resistance the engine is always working fairly hard above about 30mph. Hence it winds up sitting somewhere in the mid-RPM range and just droning. You are correct that it is a very irritable noise/vibration and slowly drives you crazy.

I actually decided to order a high-flow cat to try splicing in first. Assuming it fits. I may have to cut the floor to get adequate space, but so be it. I looked at it more while cycling the suspension and I don't think I can actually run the pipe out the back, there just isn't space past the leaf spring shackle, but I can turn it a bit and dump it, which might help too as it should direct the pressure pulses away from the floor/body. I don't know.

I did spend a whole day (6 hours of actual driving) in it on the trail and it's totally not annoying as long as you're doing technical stuff. It's going to be unbearable for snow wheeling though, as that normally involves holding 50-75% throttle for hours on end. Nobody took any usable video of me (bunch of boomers can't figure out how to do much more than make a phone call with a smart phone, what can I say), but I do have terrible knock-off GoPro footage where you can't actually hear my exhaust, but hey, watch it if you want, or don't.

Watched the video, will check out your channel. What I'll try to do is try to figure out optimal laminar flow meters/second, factored with your CFM at that RPM range.

Do you have to have a cat as a requirement or just thinking using cat to slow down the drone?

If the latter is the case you might look at old cat and punch it out. Fill void with stainless mesh. Basically fill empty cavity with stainless scrub pads. They are usually in kitchen or cleaning supply area, they look like over size SOS pads. They come in copper and stainless. Make sure ones you get are actual stainless.

The ones at walmart are not last time I looked. Magnets will not attract to actual stainless. Most the China made stamped as stainless is just carbon steel, with chrome or zinc. Last time I checked with a magnet, the "copper" and the "stainless" grabbed the magnet.

I have used them in past for electrodes when electro-plating.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,827
113
Upstate NY
I'm cheap, so I'll offer the cheap option. Put in two low budget Cherry Bomb type units inline but not with 6 inches of each other. Make the 2nd one larger diameter than the 1st. You're inline can get away with 2" exhaust without issue, so neck the 1st one down to 2" from your 2.5" exhaust and get a 2.5" for the second. I wouldn't be scared to go smaller or neck down the inlet to 1.75".

Something like this :


And aim your tailpipe at the ground if you have it to the rear of the vehicle.

It'll work. Just requires some welding.
 
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2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
Watched the video, will check out your channel. What I'll try to do is try to figure out optimal laminar flow meters/second, factored with your CFM at that RPM range.

Do you have to have a cat as a requirement or just thinking using cat to slow down the drone?

If the latter is the case you might look at old cat and punch it out. Fill void with stainless mesh. Basically fill empty cavity with stainless scrub pads. They are usually in kitchen or cleaning supply area, they look like over size SOS pads. They come in copper and stainless. Make sure ones you get are actual stainless.

The ones at walmart are not last time I looked. Magnets will not attract to actual stainless. Most the China made stamped as stainless is just carbon steel, with chrome or zinc. Last time I checked with a magnet, the "copper" and the "stainless" grabbed the magnet.

I have used them in past for electrodes when electro-plating.
Don't feel any need to check out my channel, I'm not here to push it.

The reason for going with a cat is two-fold, one it might help with the drone, and two, I'll admit the exhaust is a lot nicer smelling/feeling if you have one. I've noticed it a few times 4x4ing and if I can make it not stink as bad it would be great, that said being the motor is EFI it's nowhere near as bad as it could be. I went with the Magnaflow 53006, so it's a pretty open core and probably will behave similar to an empty cavity with some packing material, maybe? I'll see what happens when it shows up.
 

78Delta88

Master Mechanic
May 23, 2022
300
43
SW Arizona
242 CID (3.6L) = 2800 to 3600 RPM = about 215 to 280 CFM. Then some factoring as the only focus is exhaust. Biggest issue is most the math is in metric, so lots of conversion.

I researched out a new device that is being used in petroleum and other pipe contained gasses. It's not really on the market yet and kind of a modified version of the Tesla valve.

Next week or so I plan to make a couple and put on test stand. From there I can send you one, I'm just curious how it would work in a real world application.
 

2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
242 CID (3.6L) = 2800 to 3600 RPM = about 215 to 280 CFM. Then some factoring as the only focus is exhaust. Biggest issue is most the math is in metric, so lots of conversion.

I researched out a new device that is being used in petroleum and other pipe contained gasses. It's not really on the market yet and kind of a modified version of the Tesla valve.

Next week or so I plan to make a couple and put on test stand. From there I can send you one, I'm just curious how it would work in a real world application.
Well this sounds interesting. Got any diagrams of how it sort of functions?

You might not want to send it to me though, I am not in the same country as you.
 

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