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Engine/Transmission (1998.5 - 2002) Straight Pipe Drone

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Engine/Transmission (1994 - 1998) Fuel pump limits

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Am I the only one who finds it really annoying when you hear someone with a straight exhaust system on their truck? Does anyone think that the horrible droning noise being produced by their truck sounds good? A six cylinder Cummins emits the same drone sound as a six cylinder gasser (if you have a straight pipe).

It's amazing how you can kill the droning six cylinder sound and make a Cummins sound more like a V-8 with a simple flow through open chamber style muffler. Every time I hear someone with a straight pipe it always seems to be the type of people who like to rev their engine for all to hear. I just want to stop and try to talk some sense into some of these people. It embarrasses me when I see one of my fellow Cummins owners running around driving a truck that sounds like a wet vac on steroids.

When I installed my Warp Speed Performance exhaust a few years back I actually installed my muffler backwards. WSP said it would extend the life of the muffler since any moisture would pass through the muffler and not be trapped in the muffler core. WSP said you could reverse the muffler on the Dodge or Ford but not the GM trucks because it would be too loud.

The reversed muffler probably increased the dB output on my truck but it's still reasonable. At idle my truck doesn't sound much louder than stock but it does sound much more throaty. I think you can do stacks without mufflers just fine. The stacks seem to do a good job of killing the annoying drone.
 
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I'll have to take your word for it, I've never heard a cummings do anything, however, my Cummins sounds very nice with its straightpipe
 
my 6 cylinder straight pipe sounds like a combonation of a farm tractor and a peterbilt coming down the road. now ive never heard a 6 cylinder straight pipe gasser before but something tells me that it doesnt sound anything like what i just described my truck sounds like.



is straight pipe for everyone? for sure no. but in my opinion there is nothing sweeter than a straight piped cummins coming down the road. :D
 
It must be lonely... ... . being the only one with a CUMMINGS..... and not having fellow CUMMINGS owners... ... ... ... ... ... . :confused:
 
If its too loud than your too old. The only reason i have a muffler is cause of my horses, i still get to drive my old Mopar open header every now and than.
 
I love the sound of the straight piped Cummins trucks but I have to admit that mine is a little nicer to drive with the 4" Silverline exhaust I have on it now. I've never been around my truck to hear how it sounds with the muffler when pulling a load but it sounds good at an idle.
 
Roll down the windows the next time you drive by a concrete wall, guardrail , or other large solid object and listen to the sweet rumble. If any of my employees's are in my truck I like to joke with them about the exhaust sound. I cup my hand to my ear and ask them if they can hear the music. I've had to let my Foreman drive my truck a few times and it does sound sweet to hear your own truck heading down the road.
 
Actually every time i get a chance to drive by a wall, high fencing, tall buildings or a tunnel:D(am i missing one), the windows go down and from there on its just the most beautiful sound.
 
Man, you'd think the TDR spell check would keep me out of hot water! Please forgive my errant "G". I did a little research on the resonance that causes the drone sound. Apparently, the length of an exhaust system determines the rpm range at which exhaust resonance (drone) occurs. The shorter the exhaust the less of a problem resonance becomes. This is why stacks emit no resonance. This is the formula for resonance: Wavelength = 1100 X 60 X 1/RPM X 1/4 X 1/2
or

Wavelength = 8250 / RPM

Wavelength = standing wavelength
1100 = speed of sound in air in feet per second
60 = convert RPM to Revs per second
RPM = RPM
1/4 = four cylinder firings per revolution (make this 1/2 for "true
dual")
1/2 = standing wavelength is half the wavelength of a "normal" wave

I was not able to find out if the diameter of the pipe has an effect on this formula. I do know that when I replaced my turbo with a turbo with a larger 4" outlet I stopped having a problem with severe resonance vibrations at about 80 mph.

If the diameter of the pipe does effect the level at which resonance occurs I may have heard a few people running around with hacked factory 3" exhausts. I would welcome some feedback if someone has heard a 3" muffler (or resonator) delete system versus a 4" or 5" system. If the math above works in your favor your truck might sound as good as stacks.

I do know that I've heard a few Cummin's (I'm learning!) running around Austin, TX that had a serious problem with resonance droning. I have no problem with loud exhaust systems. I'm all for using factory exhaust systems for boat anchors. I'd like to have someone send me a sound byte of their 4" or 5" straight piped truck. It's highly possible a few rogue straight pipe trucks biased my view of all straight piped trucks.
 
i used to have 4" exhaust with a high flow magnaflow muffler. then one day it all changed. a dodge CUMMINS coming down the road with me standing on the sidewalk made me fall for what looked to be a 5" straight pipe. this thing just sounded mean. just deep as can be with a snappiness to it. and now i have it.
 
I'm not sure if the diameter of the pipe makes a difference, quick correction on mine, the brief drone is right at 1250, previously I said 1100, but on my way to work I double checked and realized I was wrong, mine is factory 3" sans muffler (additionally, there were no cat's put on the early `94's like mine), so its 3" and is factory length
 
My stacks resonated as well back when I ran a single turbo, I added a short donaldson muffler from a big rig and it took the drone out of it. Sounded great. Now with the twins and 5" all the way out (no muffler) it still sounds good just not as loud and no drone.
 
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