Nobody has any clue where to get this type of piping? It is the same piping used for mufflers and resonators so the rest of the pipe work can slide into the muffler.
Last edited:
Branch resonators - ways of reducing exhaust drone
- Thread starter Kristian_Wraae
- Start date
you could use Schedule 40 4" pipe, it is 4.5" OD with a .237" wall thickness (4.5 - .237 - .237 = 4.026" ID). It would be heavy, but for tuning it may be your best bet. Plumbing supply stores should sell it.
for reference, pipe and tube standard sizes:
http://www.engineersedge.com/pipe_schedules.htm
http://www.webcoindustries.com/tubing/mechanical/sizechartdrawntube.cfm
for reference, pipe and tube standard sizes:
http://www.engineersedge.com/pipe_schedules.htm
http://www.webcoindustries.com/tubing/mechanical/sizechartdrawntube.cfm
Just finished the branch resonator.
Took a while since my welder had a lot of things to see to. But now it is on.
We didn't spend much time tuning it. We just set it at 42 cm as I calculated and it is much quieter now.
My wife pointed it out immediately when I came home from the welder.
As of now it is relatively untuned so I guess I'll try to slide it out a bit to see if it dampens more around 1800-2000 rpm. But it really works wonders. Before the entire car was shaking and the rear view mirror was shaking so badly you couldn't focus. Now it is only slightly louder than stock. Something of a feat for a straight through 4 inch system.
I'll post up some high-res pictures of it later tonight.
Another benefit of the system is that if I want to race the car I can just remove the end cap of the branch resonator and I have a completely open 4 inch system.
Took a while since my welder had a lot of things to see to. But now it is on.
We didn't spend much time tuning it. We just set it at 42 cm as I calculated and it is much quieter now.
My wife pointed it out immediately when I came home from the welder.
As of now it is relatively untuned so I guess I'll try to slide it out a bit to see if it dampens more around 1800-2000 rpm. But it really works wonders. Before the entire car was shaking and the rear view mirror was shaking so badly you couldn't focus. Now it is only slightly louder than stock. Something of a feat for a straight through 4 inch system.
I'll post up some high-res pictures of it later tonight.
Another benefit of the system is that if I want to race the car I can just remove the end cap of the branch resonator and I have a completely open 4 inch system.
I have no device to measure that. Besides the resonator works by dampening a narrow frequency band so it might be difficult to measure. But it is very much quieter. I'll try to record a video when the car comes back from the under coater so you can compare with the previous one.
It went from annoyingly loud to pleasantly loud. You can still hear some drone but it is much less now. I'm not embarrassed to drive around town anymore.
Anyway my wife noticed it immediately and told me that the car sounded much quieter and she didn't know I was going to have it done.
How the addition affects performace is another matter.
It went from annoyingly loud to pleasantly loud. You can still hear some drone but it is much less now. I'm not embarrassed to drive around town anymore.
Anyway my wife noticed it immediately and told me that the car sounded much quieter and she didn't know I was going to have it done.
How the addition affects performace is another matter.
Yeah, in this case db wouldn't be a good measure as some frequencies are worse than others (good example for PC people is an 80mm fan at 50db and a 120mm fan at 50db)
Yes I don't know if there can be any side effects. I don't notice any though.
I'm really happy about how much nicer the car is to drive now.
Does anyone know of an electric 4 inch exhaust cut out? I'd like to put one at the end of the resonator.
I'm really happy about how much nicer the car is to drive now.
Does anyone know of an electric 4 inch exhaust cut out? I'd like to put one at the end of the resonator.
Enraged;1409585 said:
Yes I have been looking at that one on ebay. I just don't know if the quality is good.
I forgot my camera so the welder took some very nice hi-res pictures which he was going to email me, but he has had trouble doing so - most likely because they are too large. So he is going to send them one by one tonight.
I hope I'll have the pictures up later tonight.
We mounted it in the middle. We used a 4 inch 90 degree bend and some straight tubing. I don't know if it'll be more efficient if it was only straight pipe and no bend sections.
I hope I'll have the pictures up later tonight.
We mounted it in the middle. We used a 4 inch 90 degree bend and some straight tubing. I don't know if it'll be more efficient if it was only straight pipe and no bend sections.
how about a boost actuated cut out
http://www.youtube.com/watch?v=C556EHYUijA
http://www.supraforums.com/forum/showthread.php?t=525346
http://www.youtube.com/watch?v=C556EHYUijA
http://www.supraforums.com/forum/showthread.php?t=525346
What would be the average temperature of the exhaust gas in the exhaust system at normal operating temperature? That is post turbo.
I guess around midway between turbo and tip of muffler.
It is just so I can double check with the speed of sound. I might try to add a bit of length to the resonator. I suspect that is a bit short and actually muffles more above the resonance than at the resonnce and thus could be made more efficient if it was slightly longer.
It is just to have a sort of ballpark idea.
It is just so I can double check with the speed of sound. I might try to add a bit of length to the resonator. I suspect that is a bit short and actually muffles more above the resonance than at the resonnce and thus could be made more efficient if it was slightly longer.
It is just to have a sort of ballpark idea.
I think/feel that unless you install an egt probe back there there's too many variables to even guess at a number Kris.
If I were doing it I'd have some m>f extensions or a trombone slide on the resonator and grab the wife and head out in the real world and test.
If I were doing it I'd have some m>f extensions or a trombone slide on the resonator and grab the wife and head out in the real world and test.
It is actually made just like a trombone so it can slide in and out.
The car is at the undercoater now but when I get it back I'll try to slide it out to 50 cm from the 42 cm it is at now to see if it increases the dampening at 180-200 hz.
I was just trying to calculate the wave length in the exhaust at 180 hz and at what ever temperature is in the exhaust. Of course the temperature of the exhaust changes during it passage through the tube and thus it would have to be integrated.
The car is at the undercoater now but when I get it back I'll try to slide it out to 50 cm from the 42 cm it is at now to see if it increases the dampening at 180-200 hz.
I was just trying to calculate the wave length in the exhaust at 180 hz and at what ever temperature is in the exhaust. Of course the temperature of the exhaust changes during it passage through the tube and thus it would have to be integrated.