Motordyne Dual Shockwave w/Ti Tips Pics/Soundclips
11-20-2009, 02:24 PM
#622
That's a good point and one that I overlooked. I presume folks will still want sound clips up asap. As a comparison between setups, the relative differences may be exaggerated without allowing break in... If you want me to put more miles on each muffler I am willing to do it, but that will take time to go through 4 sets of mufflers! I can do both pre-break-in and post-break-in recordings?
Last edited by rcdash; 11-20-2009 at 02:26 PM.
11-20-2009, 03:25 PM
#624
Also try to do comparative testing with nearly the same atmospheric temperatures or at least with the exhaust pipes at a consistant temperature.
The tuning of any exhaust system changes with the temperature of the pipes.
The speed of sound in the pipes changes with the exhaust gas temperature.
The tuning of any exhaust system changes with the temperature of the pipes.
The speed of sound in the pipes changes with the exhaust gas temperature.
11-20-2009, 05:49 PM
#626
You won't need to get nearly that sophisticated on EGT. The general difference to avoid is comparing the sound of a cold start up on one system and comparing it to the sound of another system that is very hot.
....Come to think of it... I don't want to impose more test conditions on you but it would be interesting to see a comparative RTA of a cold morning cold start Vs a hot restart RTA. On any one of the axlebacks.
Just a thought.
....Come to think of it... I don't want to impose more test conditions on you but it would be interesting to see a comparative RTA of a cold morning cold start Vs a hot restart RTA. On any one of the axlebacks.
Just a thought.
11-22-2009, 03:35 PM
#629
You won't need to get nearly that sophisticated on EGT. The general difference to avoid is comparing the sound of a cold start up on one system and comparing it to the sound of another system that is very hot.
....Come to think of it... I don't want to impose more test conditions on you but it would be interesting to see a comparative RTA of a cold morning cold start Vs a hot restart RTA. On any one of the axlebacks.
Just a thought.
....Come to think of it... I don't want to impose more test conditions on you but it would be interesting to see a comparative RTA of a cold morning cold start Vs a hot restart RTA. On any one of the axlebacks.
Just a thought.
Unfortunately I could not get this done today. Was troubleshooting odds and ends all weekend (completely unrelated to the exhaust set ups) and I need to get that done to make the car safe to drive (continued W/M leaks from my plastic tank bung - sorry for delay but I'm a slow worker
)The good news is I have Thu off. So I hope to have all tested by next weekend. Maybe earlier but work is always unpredictable...
Last edited by rcdash; 11-22-2009 at 06:33 PM.
11-23-2009, 06:54 PM
#630
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for anybody that has gone from the Nismo exhaust to the Gamma exhaust, how much louder/quieter is the gamma?
ive been meaning to switch to an exhaust that sounds a bit more agressive, and even maybe slightly more loud than the nismo and the gamma exhaust has intrigued me
to Tony, have you ever measured the gamma exhaust decibel levels? idle, and 3k rpm?
ive been meaning to switch to an exhaust that sounds a bit more agressive, and even maybe slightly more loud than the nismo and the gamma exhaust has intrigued me
to Tony, have you ever measured the gamma exhaust decibel levels? idle, and 3k rpm?
11-23-2009, 08:19 PM
#632
for anybody that has gone from the Nismo exhaust to the Gamma exhaust, how much louder/quieter is the gamma?
ive been meaning to switch to an exhaust that sounds a bit more agressive, and even maybe slightly more loud than the nismo and the gamma exhaust has intrigued me
to Tony, have you ever measured the gamma exhaust decibel levels? idle, and 3k rpm?
ive been meaning to switch to an exhaust that sounds a bit more agressive, and even maybe slightly more loud than the nismo and the gamma exhaust has intrigued me
to Tony, have you ever measured the gamma exhaust decibel levels? idle, and 3k rpm?
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11-23-2009, 09:07 PM
#633
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nicee, i didnt see that video on youtube
or how bout this, since i know that you used to have hks and you say that the hks and nismo are about the same loudness
how would you compare the gamma to the hks? (i ask this because im assuming youre more familiar with the hks than the nismo)
Ive been looking for an exhaust thats around the same loudness as nismo or louder, but with a different tone and with more power gains as well. the gamma might just be what im looking for....
or how bout this, since i know that you used to have hks and you say that the hks and nismo are about the same loudness
how would you compare the gamma to the hks? (i ask this because im assuming youre more familiar with the hks than the nismo)
Ive been looking for an exhaust thats around the same loudness as nismo or louder, but with a different tone and with more power gains as well. the gamma might just be what im looking for....
11-23-2009, 09:31 PM
#634
I dont recall saying that the Nismo and HKS are just as loud as each other. From what I have heard locally the HKS is louder than the nismo. But IMO the HKS and nismo are both very quiet exhausts. I cannot say for certain if the HKS is quieter than the Gamma but the sound difference are hard to compare them without knowing the db they both put out. The HKS has a more airy higher pitched sound, while the Gamma is more of a deep bassy tone. One thing I told the owner of the white one above was that I would add test pipes to make it louder. At idle the gamma is very quiet, same as the HKS. If you have the nismo now and your looking for a deeper growl and a little more roar up top, then I would say that the gamma is a good choice. And with the options of changing out the y pipe add on's you can always make it louder if you wanted, or add HFC's or TP's.
11-23-2009, 10:40 PM
#635
Shockwave V1 FTW!!!!!!
I love going deaf.
Just figured I'd throw that out there.
Probably going to try the single soon. I have the midpipe for the single sitting in the garage right now.
I love going deaf.
Just figured I'd throw that out there.
Probably going to try the single soon. I have the midpipe for the single sitting in the garage right now.
Last edited by Z-Dub; 11-23-2009 at 10:41 PM.
11-29-2009, 08:15 PM
#639
Update on VQ exhaust comparo
Well my W/M injection system is finally leak free and the car is driveable again. I still hit a snag trying to move the evap canister back to stock. I have a part on order (thanks Sharif!). For all you folks with evoTT that want to go back to any other exhaust, I'll put together a DIY once I figure it out myself.
Let's move on to some updates. Here are all the TDX VQ exhaust options side by side (prototypes):
There are two that look identical but are different on the inside (the left most and bottom most set) - one has perforated holes and the other set has louvers (slits).
I hooked up a real time analyzer to get some baseline data for my Shockwave TDX set up. My yamaha calibration mic is in the trunk. I put it there so that it does not pick up engine noise over the exhaust.
I think I've decided to get readings from idle up to 3500 rpms at most. This seems to give a pretty good feeling for the sound levels during most cruising situations. It's really hard to snap data readings above that because the car moves too fast (need a partner!).
Here is idle (green) vs. car off (blue) in dB:
I switched to SPL display (rather than dB) for the rest of the graphs so that the image is more centered. This is 1k rpms (purple) vs 2k rpms (in yellow). I think this was in 3rd gear (see note at end of post). I believe the drone on the 5AT is in the 30-40 Hz range and becomes quite evident at 2k rpms.
This is 2k (yellow) vs 2500 (orange) rpms in 3rd gear (notice how the peaks shift to the right as rpms increase):
This is 2500 rpms (purple) vs 3100 rpms (yellow) on the highway in 5th gear. The car becomes noticeably quiet on the highway as you approach 3100 rpms - the drone is gone. Note the huge drop off in noise around 30-40 hz at 3100 rpms:
Many sound recordings and data to follow. I did a couple of things wrong using the RTA this weekend. Most notably I did not have averaging turned on and I did not record the speed/gear I was at (only rpms until I realized I needed to save that info but it was near the end of the session at that point). So the above graphs are instant snapshots but not good for comparison because noise at the same rpms in different gears (hence different speed) is significantly different. I will redo this with averaging turned on and stick to specific gear/rpm setpoints (noted below) unless folks have other ideas. In any case, I will be able to compare histograms for each exhaust setup at each of the rpms I plan to test. With the RTA I can record 10 data points easily while driving using keyboard shortcuts. Here is the plan for each exhaust:
Histogram and sound clip for:
----------
1. Car off
2. Car idle
3. 1000 rpms, 3rd gear
4. 2000 rpms, 3rd gear
5. 2500 rpms, 3rd gear
6. 3000 rpms, 3rd gear
7. 3500 rpms, 3rd gear
8. 2500 rpms, 5th gear
9. 3500 rpms, 5th gear
10. Full rev range (sound clip only)
Full week of testing ahead!
Let me know if there are any special requests for sound clips or specific types of testing.
Let's move on to some updates. Here are all the TDX VQ exhaust options side by side (prototypes):
There are two that look identical but are different on the inside (the left most and bottom most set) - one has perforated holes and the other set has louvers (slits).
I hooked up a real time analyzer to get some baseline data for my Shockwave TDX set up. My yamaha calibration mic is in the trunk. I put it there so that it does not pick up engine noise over the exhaust.
I think I've decided to get readings from idle up to 3500 rpms at most. This seems to give a pretty good feeling for the sound levels during most cruising situations. It's really hard to snap data readings above that because the car moves too fast (need a partner!).
Here is idle (green) vs. car off (blue) in dB:
I switched to SPL display (rather than dB) for the rest of the graphs so that the image is more centered. This is 1k rpms (purple) vs 2k rpms (in yellow). I think this was in 3rd gear (see note at end of post). I believe the drone on the 5AT is in the 30-40 Hz range and becomes quite evident at 2k rpms.
This is 2k (yellow) vs 2500 (orange) rpms in 3rd gear (notice how the peaks shift to the right as rpms increase):
This is 2500 rpms (purple) vs 3100 rpms (yellow) on the highway in 5th gear. The car becomes noticeably quiet on the highway as you approach 3100 rpms - the drone is gone. Note the huge drop off in noise around 30-40 hz at 3100 rpms:
Many sound recordings and data to follow. I did a couple of things wrong using the RTA this weekend. Most notably I did not have averaging turned on and I did not record the speed/gear I was at (only rpms until I realized I needed to save that info but it was near the end of the session at that point). So the above graphs are instant snapshots but not good for comparison because noise at the same rpms in different gears (hence different speed) is significantly different. I will redo this with averaging turned on and stick to specific gear/rpm setpoints (noted below) unless folks have other ideas. In any case, I will be able to compare histograms for each exhaust setup at each of the rpms I plan to test. With the RTA I can record 10 data points easily while driving using keyboard shortcuts. Here is the plan for each exhaust:
Histogram and sound clip for:
----------
1. Car off
2. Car idle
3. 1000 rpms, 3rd gear
4. 2000 rpms, 3rd gear
5. 2500 rpms, 3rd gear
6. 3000 rpms, 3rd gear
7. 3500 rpms, 3rd gear
8. 2500 rpms, 5th gear
9. 3500 rpms, 5th gear
10. Full rev range (sound clip only)
Full week of testing ahead!
Let me know if there are any special requests for sound clips or specific types of testing.
Last edited by rcdash; 11-30-2009 at 05:42 AM.
11-30-2009, 05:55 PM
#640
This is looking great so far Raj!
Maybe one thing you can do is take a snap shot @ ~2200 RPM or the subjective point at which the greatest drone occurs with the regular Shockwave tubes. Then do the same thing with the Shockwave2 at the same RPM and same throttle position. This way the RTA can give an objective measure of what is subjectively so important.
Those two data points will be the two most important points out of the whole data set.
It would also be better to measure from the driver seat. Measuring from the trunk is good for eliminating the engine induction sound but there will be a vastly different exhaust frequency response inside the trunk area.
When I was a sound technician at Hollywood Sound Labs back in the 90's I did a lot of frequency response measurements and tuning on car audio systems for sound offs. Frequency response varied greatly with position inside the cabin. Nulls, nodes and standing waves change a lot with position. Bass frequencies too.
Windows up Vs windows down. Seat level Vs ear level. Steering wheel or against the front windshield. There can be large swings in frequency response.
If possible, try to put the mic within a few inches of your ear when you do the test. That way you and the mic are measuring/hearing the same sound when you hit the capture button.
And thank you for taking the time to do this! Its work doing testing and reporting like this.
Maybe one thing you can do is take a snap shot @ ~2200 RPM or the subjective point at which the greatest drone occurs with the regular Shockwave tubes. Then do the same thing with the Shockwave2 at the same RPM and same throttle position. This way the RTA can give an objective measure of what is subjectively so important.
Those two data points will be the two most important points out of the whole data set.
It would also be better to measure from the driver seat. Measuring from the trunk is good for eliminating the engine induction sound but there will be a vastly different exhaust frequency response inside the trunk area.
When I was a sound technician at Hollywood Sound Labs back in the 90's I did a lot of frequency response measurements and tuning on car audio systems for sound offs. Frequency response varied greatly with position inside the cabin. Nulls, nodes and standing waves change a lot with position. Bass frequencies too.
Windows up Vs windows down. Seat level Vs ear level. Steering wheel or against the front windshield. There can be large swings in frequency response.
If possible, try to put the mic within a few inches of your ear when you do the test. That way you and the mic are measuring/hearing the same sound when you hit the capture button.
And thank you for taking the time to do this! Its work doing testing and reporting like this.