Motordyne Dual Shockwave w/Ti Tips Pics/Soundclips
12-29-2009, 07:19 PM
#721
Here is the V1 (yellow) vs V2 (green) at 1800 rpms:
Here is the V1 (orange) vs V2 (pink) at 2500 rpms:
Note the 20 dB reduction in peak volume with the V2 at 120 Hz! It is important to note that these snapshots do not adequately convey the general impression over a throttle and rpm range that one feels comparing the two systems. The V1 "booms". The V2 is "clean". Those are the best words to describe the difference between them.
Hope the testing with at least some quantitative data has been helpful. I'm glad to be done with the testing - tired of jacking up the car.
Here is the V1 (orange) vs V2 (pink) at 2500 rpms:
Note the 20 dB reduction in peak volume with the V2 at 120 Hz! It is important to note that these snapshots do not adequately convey the general impression over a throttle and rpm range that one feels comparing the two systems. The V1 "booms". The V2 is "clean". Those are the best words to describe the difference between them.
Hope the testing with at least some quantitative data has been helpful. I'm glad to be done with the testing - tired of jacking up the car.
What I am surprised to see though is the consistant attenuation from 1K-5K. What do you think of this? Is it a measurement error or is it real? The graph show what they show. A good reduction.... I'm just quite surprised to see it. If its real, that's great.
Also, at the drone peak of the V1 in comparison of the V2, its not just a 20db reduction of the peak, there is also a large reduction in area under the curve. All that reduction in area under the curve is what makes it so much easier on the ears.
It is interesting to see what a difference in sound can be had by diverting a relatively small fraction of the sound path from a 3" straight through tube to a 2.5" side branch.
Great testing Raj! Thank you.
Tony
Last edited by Hydrazine; 12-29-2009 at 07:21 PM.
12-29-2009, 08:34 PM
#722
You are welcome Tony. It was a bit of work, but it was a great learning experience for me and a rare opportunity to get rid of the nasty drone I've had to live with since I started mod'ing my car. I'm glad at least one of the four designs turned out so well in this regard.
In regards to the attenuation in the higher frequencies, the V2 also has some decrease compared to ALL of the other muffler designs, so I think it is real. I sampled the V2 multiple times and the plots are all similar. Is the side branch actually a perforated core muffler? Perhaps that is why there is broader spectrum frequency attenuation as opposed to just a straight pipe, which would eliminate a single frequency based on some multiple of the length of the pipe segment? I don't know what you did with the V2, but somehow it works!
In regards to the attenuation in the higher frequencies, the V2 also has some decrease compared to ALL of the other muffler designs, so I think it is real. I sampled the V2 multiple times and the plots are all similar. Is the side branch actually a perforated core muffler? Perhaps that is why there is broader spectrum frequency attenuation as opposed to just a straight pipe, which would eliminate a single frequency based on some multiple of the length of the pipe segment? I don't know what you did with the V2, but somehow it works!
Last edited by rcdash; 12-30-2009 at 04:44 AM.
12-30-2009, 07:10 AM
#723
Its a bit esoteric for the topic of this thread but did you guys notice the intervals for the V2 peaks?
~63Hz
~120Hz
~240Hz
They occur at 1 octave intervals. IE - 1/4 wave, 1/2 wave and full wave. And all at the same amplitude. Its interesting to see the symmetry of the V2 acoustics. I'm sure this has a lot to do with the way its sound is percieved.
The V1 doesn't have this symmetry.
.
~63Hz
~120Hz
~240Hz
They occur at 1 octave intervals. IE - 1/4 wave, 1/2 wave and full wave. And all at the same amplitude. Its interesting to see the symmetry of the V2 acoustics. I'm sure this has a lot to do with the way its sound is percieved.
The V1 doesn't have this symmetry.
.
12-30-2009, 01:29 PM
#724
Interesting observations Tony.
Just to complete my review of the mufflers (not V1 or V2 Shockwave) designs, which are all very similar in sound both outside and inside the car, I think the VQ is overall the mildest, and the louvered core Sebring is very similar thought the RTA shows that it peaks higher than the VQ at several frequencies but lower at a few points also. The loudest of the mufflers is the perforated core Sebring. All of these have similar droning with the worst range being around 1600-2000 rpms (peak 1800).
Here is an RTA snapshot at 1800 rpms, 4th gear, 15% throttle, with the VQ in pink and the louvered Sebring in blue:
If only the 95 Hz peak with the VQ muffler could be brought below -35 dB like the TDX2, the large VQ muffler would be fantastic (all other parts of the curve for the VQ are around or below -40 dB).
Just to complete my review of the mufflers (not V1 or V2 Shockwave) designs, which are all very similar in sound both outside and inside the car, I think the VQ is overall the mildest, and the louvered core Sebring is very similar thought the RTA shows that it peaks higher than the VQ at several frequencies but lower at a few points also. The loudest of the mufflers is the perforated core Sebring. All of these have similar droning with the worst range being around 1600-2000 rpms (peak 1800).
Here is an RTA snapshot at 1800 rpms, 4th gear, 15% throttle, with the VQ in pink and the louvered Sebring in blue:
If only the 95 Hz peak with the VQ muffler could be brought below -35 dB like the TDX2, the large VQ muffler would be fantastic (all other parts of the curve for the VQ are around or below -40 dB).
Last edited by rcdash; 01-01-2010 at 04:36 PM.
12-31-2009, 10:20 AM
#733
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01-10-2010, 08:10 AM
#736
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Nice Work Raj, great information.
Subscribing for pics and information when the V2 is available. Very interested in changing from my EvoTT to a V2 based on this thread.
Subscribing for pics and information when the V2 is available. Very interested in changing from my EvoTT to a V2 based on this thread.
01-20-2010, 07:18 AM
#738
ShockWave V2 production is complete and the quality is top notch!
I'll get pictures posted ASAP.
I like to take product pictures in real sunlight for the best images but So. Cal. has been experiencing heavy rain for the last few days and it isn't projected to clear up until Saturday. I should be able to get good pictures posted then.
I'll get pictures posted ASAP.
I like to take product pictures in real sunlight for the best images but So. Cal. has been experiencing heavy rain for the last few days and it isn't projected to clear up until Saturday. I should be able to get good pictures posted then.
01-20-2010, 07:27 AM
#739
Even with the APS 3" test pipe exit diameter narrowing to 2.5" for the TDX (with an abrupt transition where the flanges bolt up), the MD exhaust made the same power as the evoTT. With the full 3", I'm sure it'll make even more.
Last edited by rcdash; 01-20-2010 at 07:29 AM.