Quiet 3" Muffler

[68ford]

Firm believer that if back pressure/ leaving exhaust in the cylinders makes more torque because of the restriction, something else is not optimal.
Getting all the burnt, non combustion supporting gases out of the cylinder to make room for more air and fuel will/ should make the most power.
Other wise everyone would be installing egr valves ;D
2 stroke engine make so much power because of efficient scavenging.
Same goes for a cam with tight lobe sep and zero backpressue exhaust, always makes more torque.

 

[blubuckaroo]

Firm believer that if back pressure/ leaving exhaust in the cylinders makes more torque because of the restriction, something else is not optimal.
Getting all the burnt, non combustion supporting gases out of the cylinder to make room for more air and fuel will/ should make the most power.
Other wise everyone would be installing egr valves ;D
2 stroke engine make so much power because of efficient scavenging.
Same goes for a cam with tight lobe sep and zero backpressue exhaust, always makes more torque.

So, are you trying to make this vehicle quieter too?
I think, in your case, a crossover of some type would be the best option.

 

[DirtDonk]

Same problem here. Mine is too loud, not happy with it because it drones on the highway at 2100 rpms. Around town it's fine.
Switched from smaller magnaflow, 2- 2.5" to 3" to larger magnaflow, I believe 24" from bcbroncos.
Ford racing Coyote engine.

How can I get rid of the drone?

Not to hijack the original thread, and it does still pertain to the exhaust solutions being talked about. But how is your exhaust set up?
What size tubing? What length and exit point? Single or dual?
And where exactly, and how are the mufflers mounted to the vehicle?
Is it a stock Coyote, or hopped up at all?

These things, while maybe not being as important as the muffler itself sometimes, are still very pertinent to how much and where drone occurs.
Sometimes it's just a simple resonance effect from the muffler being too close to the wrong body panel (such as an un-reinforced floor panel). Other times it's the size of the tubing mated up to the performance characteristics of the engine. And of course, sometimes it's just the muffler design alone.

Got pics? (assuming rcm does not mind the continuation of their thread?)

Paul

 

[blubuckaroo]

Not to hijack the original thread, and it does still pertain to the exhaust solutions being talked about. But how is your exhaust set up?
What size tubing? What length and exit point? Single or dual?
And where exactly, and how are the mufflers mounted to the vehicle?
Is it a stock Coyote, or hopped up at all?

These things, while maybe not being as important as the muffler itself sometimes, are still very pertinent to how much and where drone occurs.
Sometimes it's just a simple resonance effect from the muffler being too close to the wrong body panel (such as an un-reinforced floor panel). Other times it's the size of the tubing mated up to the performance characteristics of the engine. And of course, sometimes it's just the muffler design alone.

Got pics? (assuming rcm does not mind the continuation of their thread?)

Paul

Well Paul, don't you agree that drone happens when the pipes are too big?

 

[nvrstuk]

Muffler design creates drone. I know guys running flowmasters with 2" dia pipe and yes, miserable drone. Change muffler and like magic, the drone is gone.

 

[DirtDonk]

Well Paul, don't you agree that drone happens when the pipes are too big?

I don't know, but I don't think it's that simple. At least it's not the only criteria.
But then again, what do you mean by "too big" in this case? Like, just more than needed for the rpm range generally used (as in, dual 2.5's instead of dual 2.25's?), or something like putting a single 5" diesel pipe on a 302? Or in-between such as dual 3's?
Exaggerating with that diesel size of course, but you get the point.

I've heard plenty of dual 3" pipes that did not drone though (on passenger cars), and plenty of single 2.5's that did (on Broncos and other vehicles).
Having worked with Corsa exhaust (who are legendary at overthinking drone!) every engine combination needs a slightly different design to guarantee no drone. But luckily there is often a wide range of acceptable designs and sizes.

So while I think you're right to a certain extent, I don't think the "too big equals drone" is a universal truth.

Paul

 

[DirtDonk]

Hmm, I wonder if my buddy remembers what he had on his Chevy a few years ago. I'll have to ask.
Was the single worst case of drone I have EVER experienced. Now that I think about it, it might have been his 2000's-ish GMC Denali SUV (he had a "Denali" pickup too I think) with I believe dual MagnaFlows on it. But not super big pipes I didn't think.
But it was so obnoxious I would not drive more than around town with it. And even then I wore ear plugs.

I do not remember seeing big pipes (like dual 3's) coming out the back, but I don't really remember that detail clearly.

Paul

 

[blubuckaroo]

I don't know, but I don't think it's that simple. At least it's not the only criteria.
But then again, what do you mean by "too big" in this case? Like, just more than needed for the rpm range generally used (as in, dual 2.5's instead of dual 2.25's?), or something like putting a single 5" diesel pipe on a 302? Or in-between such as dual 3's?
Exaggerating with that diesel size of course, but you get the point.

I've heard plenty of dual 3" pipes that did not drone though (on passenger cars), and plenty of single 2.5's that did (on Broncos and other vehicles).
Having worked with Corsa exhaust (who are legendary at overthinking drone!) every engine combination needs a slightly different design to guarantee no drone. But luckily there is often a wide range of acceptable designs and sizes.

So while I think you're right to a certain extent, I don't think the "too big equals drone" is a universal truth.

Paul

Well maybe it's the owners denial, but every full 3" exhaust I've been in had drone. Both single and dual. They can say what they want. The drone is there.
I'm talking about full length 3" here. Not just 3" tips.

 

[DirtDonk]

I assumed the full system and not just tips. Though tips do change the tone a lot more than I would have given them credit for!
One of the loudest Broncos I've ever ridden in was the same guy's '77 that I had sold him a muffler based on my experience with other vehicles. It was a single-in single-out Gibson round welded (straight through type) 2.5" all the way out the back passenger side. Bronco was topless most of the time.
These are well known for being quiet at idle and fairly toney and almost loud under full throttle. Well, in spite of others good experiences (including 100's of customers with bigger hard top rigs (F150's, GM trucks, Full-Size Broncos, etc.) this was loud from idle all the way up, and it was drone city!
No way to understand that one, since it was the same full-length muffler (maybe 28" I want to say?) I'd used on tons of vehicles before, in both single and dual tip layouts.

Felt bad myself, but luckily he actually liked it! At least I hope he wasn't just saying that.

Paul

 

[68ford]

We don't have the luxury of space, but I have heard of numerous version of "anti drone pipes" welded next to a muffler with a plug on the end ending drone.

https://images.app.goo.gl/ghw51b3gQw3Tepko8
If that doesn't work, Google anti drone pipes, you'll get the idea

 

[DirtDonk]

Yep, I think I know what you're talking about. Same thing (but different!) that they do on modern air intake systems as well.
And basically, or at least in part what Corsa does inside their mufflers too.

Paul

 

[rcmbronc]

This is all great info. Keep adding all you want. I have been through I think 6 different mufflers on this truck. I had a 351W with 2.5" pipe to a single muffler with 3" out. Not bad sounding. The two into one I think helps some of the drone. With these new mufflers I get a slight drone at idle but not above that.

One of these days I am going to own a very mild truck with a nice quiet exhaust. The rear four link I have just does not give enough room out there for alot of exhaust. I think if I would send the exhaust out the side for the truck it may be better than under it. Also if I enclosed the area in the rear bed where the coil over shocks come up through the floor would help alot.

 

[blubuckaroo]

I think the problem here is that owners don't know how to recognize exhaust drone. Most don't even know what it is, so how can they say they don't have it.?
Look up Drone!
It's a reverberation or echo of the original sound. Large diameter pipes makes it worse.