Figure this is worth a new thread. I'm gonna type alot as usual but it's worth reading. Spoiler alert, this really works.
In another thread, I mentioned I was experiencing a slight resonance in the cab, effectively, off the left, forward, top corner, between 1700 and 2000 rpm, running 2.5" off the headers, into single 3", thrush welded (flowmaster knockoff), side exit, before rear tire.
All things considered it was tolerable.....at least I thought so but the fact it was coming from the corner, of one side of the cab, not the whole cab, made it annoying. Window cracked or down, it decreased significantly in sound level. After reading about different resonators, decided to try some redneck tests, so i blocked one tip with a t shirt.
The exhaust note went to a couple steps above stock. Crazy quiet, too quiet. Kinda unbelievable really. It proved that if permanently duplicated, a person could have an insanely quiet exhaust note, using any muffler and no catalytic converters, hard to believe but true.
That was too quiet and the idea of having one, blocked exhaust tip, screwed with the perfectionist living in my brain.
Every gear head, is afraid to lose any level of performance, so inline resonators aka glass packs, didn't appeal.
I went back to the 1/4 wave tube resonator, concept, that kept popping up in searches. It's even been discussed here before. I won't bother reposting the formula, to determine pipe length, a simple online search will reveal it.
I tried to target 1700~1800 rpm, kinda in the middle of my drone zone.
I was using material left over from the Y pipe build, so this only cost time. Whole project including muffler still cost less than having it done, and this is all mandrel. Performance aspect aside or lack there of, I like the idea of a chambered muffler. This tube resonator, doesnt restrict flow in anyway, another bonus. Plus swapping the chambered for turbo style mufflers, wouldnt guarantee no drone. So there's the subjective, justification aspect.
I've attached photos below, to give an idea of what this resonator looks like, kinda funky, very non traditional. It was a tight fit but thankfully everything fit once welded.
Some people make the tube length adjustable, good idea, so it can be finely tuned. I may do that too, just out of my own curiosity.
Put a few miles on my truck. Observations.
As I approach 1600 rpm and move towards 1700, it's like the drone is about to start, the sound level increases, bass of the tone increases however the sound doesn't bounce off the cab corner, like it used to, instead it appears to come from the back window~bed in an even manner, can almost hear engine pulses, even then the sound is mild, and actually nice.
As the rpms move from 1700 into 1800, due to past experience, I expect the drone to come in strong. That doesn't happen, instead it's like a switch is flipped and resonance disappears completely, sound level drops considerably, hard to explain, smooth and quiet but clean exhaust note from the pipe end, were it should be.
1800 rpm into 2000+ or say 60~70+ mph, it used to feel and sound like rolling thunder, I liked it but kinda loud with the windows up, on a cold day, but now, quiet, dare I say loud stockish, exhaust note, as if it were a full length tailpipe over the axle out the side. Perfect for interstate speeds. I found myself cruising along at 65~70 mph, in places I shouldn't, it was that quiet, didn't realize how fast I was going.
Also noticed under load or if I lug the engine a little going up a hill, before it wanted to drone a bit, now, exhaust noise actually gets quieter, regardless of rpm under load. It's strange and defies expectations but it's nice.
The sound out the exhaust tip is about the same for the most part, i guess, I didn't realize how much bark it had, till the cab noise was silenced with the resonator and now I can hear it. Although I've been told twice, by two different people, I didn't realize you were here, I didn't hear your truck.
Driving is much nicer now, suppose cause it's a "tuned" exhaust.
I heard the tires, road noise today, haven't heard that since I put the thrush muffler on, and the tires aren't loud, normal Street tire road noise, doing 70, that's saying something, the 2000 rpm drone victims, get what I'm saying.
After research, seems this ideas been around forever, even OE exhaust systems utilize some aspect of this idea. Even OE intakes aka silencers.
No regrets, would definitely recommend someone with resonance issues to give it a try, research it, a lot of info out there, for 1/4 wave tube resonators, from different make/models.
Edit....the 1/4 wave resonator works but sticking a short glass pack after the muffler can work better over a broader rpm range.
In another thread, I mentioned I was experiencing a slight resonance in the cab, effectively, off the left, forward, top corner, between 1700 and 2000 rpm, running 2.5" off the headers, into single 3", thrush welded (flowmaster knockoff), side exit, before rear tire.
All things considered it was tolerable.....at least I thought so but the fact it was coming from the corner, of one side of the cab, not the whole cab, made it annoying. Window cracked or down, it decreased significantly in sound level. After reading about different resonators, decided to try some redneck tests, so i blocked one tip with a t shirt.
The exhaust note went to a couple steps above stock. Crazy quiet, too quiet. Kinda unbelievable really. It proved that if permanently duplicated, a person could have an insanely quiet exhaust note, using any muffler and no catalytic converters, hard to believe but true.That was too quiet and the idea of having one, blocked exhaust tip, screwed with the perfectionist living in my brain.
Every gear head, is afraid to lose any level of performance, so inline resonators aka glass packs, didn't appeal.
I went back to the 1/4 wave tube resonator, concept, that kept popping up in searches. It's even been discussed here before. I won't bother reposting the formula, to determine pipe length, a simple online search will reveal it.
I tried to target 1700~1800 rpm, kinda in the middle of my drone zone.
I was using material left over from the Y pipe build, so this only cost time. Whole project including muffler still cost less than having it done, and this is all mandrel. Performance aspect aside or lack there of, I like the idea of a chambered muffler. This tube resonator, doesnt restrict flow in anyway, another bonus. Plus swapping the chambered for turbo style mufflers, wouldnt guarantee no drone. So there's the subjective, justification aspect.
I've attached photos below, to give an idea of what this resonator looks like, kinda funky, very non traditional. It was a tight fit but thankfully everything fit once welded.
Some people make the tube length adjustable, good idea, so it can be finely tuned. I may do that too, just out of my own curiosity.
Put a few miles on my truck. Observations.
As I approach 1600 rpm and move towards 1700, it's like the drone is about to start, the sound level increases, bass of the tone increases however the sound doesn't bounce off the cab corner, like it used to, instead it appears to come from the back window~bed in an even manner, can almost hear engine pulses, even then the sound is mild, and actually nice.
As the rpms move from 1700 into 1800, due to past experience, I expect the drone to come in strong. That doesn't happen, instead it's like a switch is flipped and resonance disappears completely, sound level drops considerably, hard to explain, smooth and quiet but clean exhaust note from the pipe end, were it should be.
1800 rpm into 2000+ or say 60~70+ mph, it used to feel and sound like rolling thunder, I liked it but kinda loud with the windows up, on a cold day, but now, quiet, dare I say loud stockish, exhaust note, as if it were a full length tailpipe over the axle out the side. Perfect for interstate speeds. I found myself cruising along at 65~70 mph, in places I shouldn't, it was that quiet, didn't realize how fast I was going.
Also noticed under load or if I lug the engine a little going up a hill, before it wanted to drone a bit, now, exhaust noise actually gets quieter, regardless of rpm under load. It's strange and defies expectations but it's nice.
The sound out the exhaust tip is about the same for the most part, i guess, I didn't realize how much bark it had, till the cab noise was silenced with the resonator and now I can hear it. Although I've been told twice, by two different people, I didn't realize you were here, I didn't hear your truck.
Driving is much nicer now, suppose cause it's a "tuned" exhaust.
I heard the tires, road noise today, haven't heard that since I put the thrush muffler on, and the tires aren't loud, normal Street tire road noise, doing 70, that's saying something, the 2000 rpm drone victims, get what I'm saying.
After research, seems this ideas been around forever, even OE exhaust systems utilize some aspect of this idea. Even OE intakes aka silencers.
No regrets, would definitely recommend someone with resonance issues to give it a try, research it, a lot of info out there, for 1/4 wave tube resonators, from different make/models.
Edit....the 1/4 wave resonator works but sticking a short glass pack after the muffler can work better over a broader rpm range.
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