John,
Just a small clarification; the rotors of SC do not touch each other. There is a very small but critical clearance between them.
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CTSC source of whining or how to quiet it down
- Thread starter goldNSX
- Start date
John,
Just a small clarification; the rotors of SC do not touch each other. There is a very small but critical clearance between them.
I have the stock air box and the RM (or B&B) exhaust. The exhaust is louder than stock but I can still hear the supercharger whine.
Thanks for the info on the rotors not meshing. I wonder if the whine comes from the gears? If not, then where might it be coming from? I notice it when the inlet butterfly is open and it certainly appears to be coming from the inlet, but maybe it's coming from another location.
By the way, is there any dyno data comparing the stock air box to other types of air filters on a Comptech supercharged engine? Would the gains from an aftermarket filter only be noticeable at higher engine speeds? Would it be possible for horsepower/torque to be lost at lower RPMs where we typically do most of our street driving? It seems plausible that the cold air coming from the stock inlet would be better at lower engine speeds than a low restriction air filter that is ingesting warm engine compartment air, but without data it's only a guess.
John
Thanks for the info on the rotors not meshing. I wonder if the whine comes from the gears? If not, then where might it be coming from? I notice it when the inlet butterfly is open and it certainly appears to be coming from the inlet, but maybe it's coming from another location.
By the way, is there any dyno data comparing the stock air box to other types of air filters on a Comptech supercharged engine? Would the gains from an aftermarket filter only be noticeable at higher engine speeds? Would it be possible for horsepower/torque to be lost at lower RPMs where we typically do most of our street driving? It seems plausible that the cold air coming from the stock inlet would be better at lower engine speeds than a low restriction air filter that is ingesting warm engine compartment air, but without data it's only a guess.
John
No need to quiet down the whine as it will almost certainly not be a problem with soundcheck (high frequency whine doesn't register much decibel-wise).
Just over a week ago, my newly imported US CTSC NSX passed the very strict import registration soundtest here in The Netherlands for import vehicles originating from outside Europe.
Testing is done: driving 50km/h both in 2nd and 3rd gear and flooring the throttle, 3 mics are picking up the sound over I think a 100mtr distance, 1 at the start, 1 in the middle and 1 at the end of the 100mtr testing distance
Mods I made were:
-OE intake/airfilter with some extra foam in the intake box
-Comptech engine cover installed (this dampens the sound of the CTSC in the engine bay), without the cover, it is definatly louder outside the car
-OE exhaust muffler
Testing inspector told me the soundlevel was close to the allowed limit, but it did pass:smile:
Just over a week ago, my newly imported US CTSC NSX passed the very strict import registration soundtest here in The Netherlands for import vehicles originating from outside Europe.
Testing is done: driving 50km/h both in 2nd and 3rd gear and flooring the throttle, 3 mics are picking up the sound over I think a 100mtr distance, 1 at the start, 1 in the middle and 1 at the end of the 100mtr testing distance
Mods I made were:
-OE intake/airfilter with some extra foam in the intake box
-Comptech engine cover installed (this dampens the sound of the CTSC in the engine bay), without the cover, it is definatly louder outside the car
-OE exhaust muffler
Testing inspector told me the soundlevel was close to the allowed limit, but it did pass:smile:
Exactly. What will set off a db meter are lowe frequencies. Outdoors, high frequencies dissipate quickly and they just will not register much on a meter even when you can hear it. Human hearing is very different than the way a db meter reads volume level.
The Accord clip sounds nothing like my CTSC. The CTSC in my NSX is MUCH quieter. Also the engine cover helps a lot, it should stay on. You can also line the engine cover with acoustical material for the test and it will absorb much of the sound. Just make sure it is not touching the engine parts and remove after because it also will keep heat in. You can even build a sort of muffler by raising the cover a little with washers, then tacking some acoustical absorbing material to the back of the cover and sandwiching it to the cover with mesh. I don't think you will need to do this, but it is an option. The CTSC on an NSX is just not that loud... and yes, you only hear it at full throttle and higher RPM's. Your exhaust will most likely still be the loudest part.
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With the a Taitec you can't hear it whine, ok. :wink: BUT: We almost get hung up the next tree if we get caught with an exhaust as loud as a Taitec.
No joke: You loose your driving license in our country.
rsevo6 said:
Very, very interesting! How much is the max dB-level you have to be within? Does your car have a header? Too bad I have short gears, this results in more dB in the specific test. Thanks for the input, I see some light at the end of the tunnel.
Damn man, that sucks.With the a Taitec you can't hear it whine, ok. :wink: BUT: We almost get hung up the next tree if we get caught with an exhaust as loud as a Taitec.
No joke: You loose your driving license in our country.
May I offer a suggestion? Ignore it and not read if you decline:
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Like what others mentioned, engine cover will help a lot, keep the oem catalytic converter, stock exhaust.
-Maybe stay NA? Forget about SC?
-Postpone install until after the test?
-Whipple suppose to be quieter than Autorotor
When my NSX was on dyno, you can't hear the whine from SC at all. I assume they will check the sound level from the exhaust? if that is the case, you got no worries.
Here are some videos of the NSX accelerating underload, on my dyno runs, the noise from dyno roller over powered
the noise from SC whine, there are zero noticeable whine on my dyno run videos.
Thomas's 02+ CTSCed NSX with Taitec JGTC exhaust+cats, not too loud imho:
http://www.youtube.com/watch?v=L0KmSTL_QDk
http://www.youtube.com/watch?v=Eauow7vhlPY
http://www.youtube.com/watch?v=yVFKx6ckf18
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Thanks for the info. Esp. on Thomas's 02+ NSX it's not noticable in the video, ok louder exhaust on the car than allowed in my country. rsevos6's success in passing (at the limit) the test in Europe make me think that it should pass here too with some additional sound dampening. So it's not a mission impossible. :wink: I may got nervous by the videos I've posted before.
Very, very interesting! How much is the max dB-level you have to be within? Does your car have a header? Too bad I have short gears, this results in more dB in the specific test. Thanks for the input, I see some light at the end of the tunnel.
With testing a import vehicle from outside of Europe, here in Holland the allowed noise level is dependant on several things:
-year of the car
-type of car
-power/weight level
-measuring error correction
With testing of my '98 CTSC NSX I think this amounted to:
-allowed max noise level 78db
-raise because it is a gearbox model (not auto) 2db
-raise because of power/weight level (sportscar) 2db
-raise for measuring error correction 1db
Total allowed noise level for my car: 83db
My CTSC NSX with the above mentioned alterations measured at exactly the allowed limit of 83db (WAS VERY QUIET IN MY OPINION!!)
The car also has CT headers which were on the car while testing (figured it too much work to change and I don't have the OE headers anyway).
When the OE headers are on, it might be even a little more quiet.
Now the test is passed and the car has been titled, I will change back to unifilter/possibly other intake and either Comptech or Taitec GTLW exhaust as I have both :smile: :wink:
NOW let's make noise again
:biggrin:
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I hope we have this kind of alterations too. Our max. noise level is 77 dB if I recall correctly which is very, very quiet in terms of automobile noises. It's that low that the most of the noise is tire related and not engine related. On newer cars you hear nothing but tire noise.
I have a Taitec header and according to http://www.scienceofspeed.com/products/exhaust_airflow_products/NSX/Fujitsubo/headers/ it's a high level noise source. For the test it has to go.
Last edited:
Power_Seller
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OP,
If you dont love the sound of a SC deep in your heart...nothing can fix this problem
PS
If you dont love the sound of a SC deep in your heart...nothing can fix this problem
PS
That accord uses a different blower, much lowder than the Autorotor or Whipple IMO.
My experience with whipple is that the whine is not as loud as the intake note it replaces (driven CTSC and NA NSXs back to back, both with stock exhaust, CTSC with aftermarket headers). I've been told the Autorotor is louder, in which case I'd guess noise level is probably very similar to stock NSX (assuming all other items on NSX are stock like gears, airbox, filter, cats, exhaust, engine cover).
If your NSX is drive-by-physical cable vs drive-by-wire you could always adjust (lengthen) the cable so that flooring it doesn't equal flooring it. Inhibiting petal travel could also achieve the same (even on newer drive-by-wire NSXs).
It's too bad they don't run the test at higher speeds. The NSX's shape plus small frontal area would likely reduce wind noise compared to other cars, leaving more room for small additions of noice from SC or such.
