Hey guys, I absolutely love my 4 inch turbo back straight pipe but i have got to try to stop the drone while towing. I'm going to probably be towing alot in the next few months and decided to install a muffler, I have 2 on hand. A 24 inch long 7 inch round stainless magnaflow or a 41 inch long straight through donaldson. I'm thinking the donaldson because it seems like people like it alot but will it help with the drone i get?
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Which muffler for towing?
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lotta folks using two muffs to eliminate drone. drone can still be a problem with single straight throughs... . not always, but it happens.
to answer your question though... . i'd recommend the donaldson for what your concerns are. i used a single donaldson 51" on my 99and it had a nice tone and zero drone.
j
to answer your question though... . i'd recommend the donaldson for what your concerns are. i used a single donaldson 51" on my 99and it had a nice tone and zero drone.
j
Keep in mind that a lot of your noise has to do with the last 12 inches of pipe in your system. I have a 4 inch system into stacks right now and it's loud, don't get me wrong, but no drone. For about 3 months I had 4 inch to just a foot and a half long piece of 5 inch turning out just before the rear wheel. I did it for the effect of the smoke coming out there, but didn't realize how much it would alter the sound. Just driving down the road, completely unloaded, that thing would give me a headache. It had that drone that you can feel in your chest when you got on it. It all has to do with the outlet diameter, the length of straight pipe before the outlet, the material of the outlet, and the mounting. A short piece of 5 inch thin walled galvanized pipe, held up by a rachet strap nonetheless, reverberated in ways you can't imagine, regaurdless of the rest of the system. The 4ft tall, thick walled, chromed 4inch diameter stacks, hard mounted in the bed by 1/8" thick, 5 inch wide stainless steel brackets on the other hand, are actually quite tolerable, even towing my Ramcharger at 75mph in 3rd gear. My turbo is actually louder than the pipes most of the time.
Does your exhaust dump completely outside of the body? If it dumps under the bed (or cab) that magnifies the drone effect, I have a 4" turbo back that dumps in the stock location, and I can only hear it when I have 100% load on the engine, of course my 38. 5x16x16 Super Swampers provide enough drone to muffle a Kenworth
I have built many an exhaust system for pick-ups and school buses and have quite a bit of experience with it.
I can't say if a straight through Nelson 4" x 51" long wil work well as there are many other variables.
I installed a RESONATOR on one of my trucks and it functions very well to remove drone. I use it as a stand alone along with the twin 5" shorty stacks and ALL rubber isolators through-out.
I also install them onto school buses, cuz it sounds cool to hear a bus whistle. I have also installed many a straight through Nelso muffler. You can get 'em various lenghts but most common is the 51-incher. That thing is huge but also allows for good turbo whistle.
The 51 incher is Nelson 86131M This was featured as an article in out TDR magazine. You'd have to find the room to install this. They are 9" dia body, so it's a bit fatter than the common performance mufflers you see that are 6" and polished.
The resonator is going to be 4" straight through at 16" overall with 9" dia. body. It is 86144M. This is much easier to install becasue it be so short.
Sorry, forgot to add that a resonator is designed to remove drone. What its made for. The second gen rigs ues them. They are supposed to be placed close to the turbo (prior to the muffler)
I can't say if a straight through Nelson 4" x 51" long wil work well as there are many other variables.
I installed a RESONATOR on one of my trucks and it functions very well to remove drone. I use it as a stand alone along with the twin 5" shorty stacks and ALL rubber isolators through-out.
I also install them onto school buses, cuz it sounds cool to hear a bus whistle. I have also installed many a straight through Nelso muffler. You can get 'em various lenghts but most common is the 51-incher. That thing is huge but also allows for good turbo whistle.
The 51 incher is Nelson 86131M This was featured as an article in out TDR magazine. You'd have to find the room to install this. They are 9" dia body, so it's a bit fatter than the common performance mufflers you see that are 6" and polished.
The resonator is going to be 4" straight through at 16" overall with 9" dia. body. It is 86144M. This is much easier to install becasue it be so short.
Sorry, forgot to add that a resonator is designed to remove drone. What its made for. The second gen rigs ues them. They are supposed to be placed close to the turbo (prior to the muffler)
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Arent the Cummins Loud to begin with? Thats the understanding that I have. Most of the time you can add another muffler in line with an existing muffler to help cut out some of the drone. But most of the time when you put on a performance exhaust and or a performance muffler you will get drone. Putting in a second muffler can help but wont totally take it away.
Drone and flat out loudness are two seperate things. Loudness refers to the pure decible level of a particular sound. A muffler is mainly designed to reduce the loudness of a motor, normally with baffles that cut off the sound waves as they pass through. Or a straight through muffler which has holes in the inner wall that catch the sound waves, and then are baffled in a chamber outside of the flow of exhaust.
Drone is not neccesarily loudness. Drone has to do with loudness at a specific frequency. Depending on the frequency, the loudness at which a sound is no longer tolerable (refered to as the threshold of pain) changes. A big diesel motor already puts out a low frequency sound by nature, which is compounded by the large diameter and long straight runs of exhuast pipe on a truck. This is then compounded even more by resonant frequency, in which a section of exhaust pipe is close to the length of the actual sound wave, or a multiple thereof, and the crest of the wave on the way out hits the crest of the wave on the way in and multiplies the amplitude. This same theory could apply to your truck frame or to the sheet metal of the cab. This is why our trucks actually get quieter as they wind out. The frequency a higher revving motor puts out is higher than the frequency a lower revving motor puts out, and the higher revving motor no longer finds the resonant frequency of the pipe/frame/cab.
This is what I was trying to say without turning into a scientist in a lab coat... . or worse yet, your high school physics teacher.
The tip may help, yes. Most dress-up exhaust tips are made of heavier gauge steel and chromed, or better yet, all stainless. a little clamp on 6 inch long tip might not do a whole lot though, as opposed to a 12 inch full tailpipe style tip.
You can try the muffler, but all you're really doing is trying to bring that decible level back down within the tolerant area for that given frequency, as opposed to changing the frequency to one that reduces resonance. It also may be more work than you need to do to fix your problem. Also, if you find a tolerable frequency without resonance, you can still p-off your neighbors without giving yourself a headache.
Drone is not neccesarily loudness. Drone has to do with loudness at a specific frequency. Depending on the frequency, the loudness at which a sound is no longer tolerable (refered to as the threshold of pain) changes. A big diesel motor already puts out a low frequency sound by nature, which is compounded by the large diameter and long straight runs of exhuast pipe on a truck. This is then compounded even more by resonant frequency, in which a section of exhaust pipe is close to the length of the actual sound wave, or a multiple thereof, and the crest of the wave on the way out hits the crest of the wave on the way in and multiplies the amplitude. This same theory could apply to your truck frame or to the sheet metal of the cab. This is why our trucks actually get quieter as they wind out. The frequency a higher revving motor puts out is higher than the frequency a lower revving motor puts out, and the higher revving motor no longer finds the resonant frequency of the pipe/frame/cab.
This is what I was trying to say without turning into a scientist in a lab coat... . or worse yet, your high school physics teacher.
The tip may help, yes. Most dress-up exhaust tips are made of heavier gauge steel and chromed, or better yet, all stainless. a little clamp on 6 inch long tip might not do a whole lot though, as opposed to a 12 inch full tailpipe style tip.
You can try the muffler, but all you're really doing is trying to bring that decible level back down within the tolerant area for that given frequency, as opposed to changing the frequency to one that reduces resonance. It also may be more work than you need to do to fix your problem. Also, if you find a tolerable frequency without resonance, you can still p-off your neighbors without giving yourself a headache.
Drone ?
5th gear at 60 or 70 mph. Do you know the rpm's ? What is your rear end ratio for these numbers ? Could it be you are running to low of rpm for the speed and torque being applied, or maybe too high ? Mine has a bad sound if the rpm's drop too low especially when towing a load. Our trucks do have a "sweet spot" where everything works best including miliage and engine wear.
5th gear at 60 or 70 mph. Do you know the rpm's ? What is your rear end ratio for these numbers ? Could it be you are running to low of rpm for the speed and torque being applied, or maybe too high ? Mine has a bad sound if the rpm's drop too low especially when towing a load. Our trucks do have a "sweet spot" where everything works best including miliage and engine wear.
And how the hell does this help anything?
AMen, brother.
To answer your RPM question- you are running about 2050rpm at 70mph.
Daniel
Cmon, don't you just feel better knowing he doesn't like mufflers?
... unless by "muffs" he's not referring to "mufflers" but I could safely assume he's in the wrong forum if thats the case.
... unless by "muffs" he's not referring to "mufflers" but I could safely assume he's in the wrong forum if thats the case.
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