MY Drone noise can not be filtered by using sound damping materials
02-25-2013, 02:50 PM
#1
Pro
Thread Starter
MY Drone noise can not be filtered by using sound damping materials
This weekend I drove from GA. to IL.
Newly purchased 2005 Corvette "Road Trip".
My improvements before trip
Peel & Seal, 3 layers in rear cabin, 1 layer on both wheel wells, and 1 layer behind both seat.
The rear cabin was loaded with 2 soft-shell-suitcases, and 3 thick winter coats. The Peel & Seal plus the suitcases and coats should be more than needed to damped my exhaust drove noise problems.
I used a Bruel & Kjaer Hand-held Analyzer Type 2250 (This device is used to measure sound levels at different frequencies in db)
At cruising speed of 70 to 80 mph I measured the following.
40Hz at 102db
125hz at 102db
40hz and 125hz are low frequencies. 96db in low freq in very loud.
I am getting readings of these freqs at 102db. THis is not GOOD to the body.
Frequencies this low can only be filtered by using a large solid mass that will not resonate.
Most filter materials used will only help with the higher frequencies and road noise. My corvette is like a giant sub-woofer mounted on rubber tires. Everything in the car is resonating at these freqs. Plus the shape of the rear window amplifies the effects
Some components of low freq can not be heard by the human ear but can still cause some damage to your ears if exposed too long. My car caused my "ear to jaw" to hurt after 6 hours of driving...I am only 49 year of age.
The exhaust system in my car is "engine to cats to resonators to straight pipe". TOO LOUD.
Solution for me....Going back to OEM.
Newly purchased 2005 Corvette "Road Trip".
My improvements before trip
Peel & Seal, 3 layers in rear cabin, 1 layer on both wheel wells, and 1 layer behind both seat.
The rear cabin was loaded with 2 soft-shell-suitcases, and 3 thick winter coats. The Peel & Seal plus the suitcases and coats should be more than needed to damped my exhaust drove noise problems.
I used a Bruel & Kjaer Hand-held Analyzer Type 2250 (This device is used to measure sound levels at different frequencies in db)
At cruising speed of 70 to 80 mph I measured the following.
40Hz at 102db
125hz at 102db
40hz and 125hz are low frequencies. 96db in low freq in very loud.
I am getting readings of these freqs at 102db. THis is not GOOD to the body.
Frequencies this low can only be filtered by using a large solid mass that will not resonate.
Most filter materials used will only help with the higher frequencies and road noise. My corvette is like a giant sub-woofer mounted on rubber tires. Everything in the car is resonating at these freqs. Plus the shape of the rear window amplifies the effects
Some components of low freq can not be heard by the human ear but can still cause some damage to your ears if exposed too long. My car caused my "ear to jaw" to hurt after 6 hours of driving...I am only 49 year of age.
The exhaust system in my car is "engine to cats to resonators to straight pipe". TOO LOUD.
Solution for me....Going back to OEM.
02-25-2013, 02:54 PM
#2
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Member Since: Sep 2005
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St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15- '16-'17-‘18-‘19-'20-'21
NCM Lifetime Member
Find a used NPP and retro fit it. Install the mild to wild kit and you're good to go.
02-25-2013, 03:08 PM
#4
Drifting
45 years of modifiying each of my car's exhausts ended with the purchase of my 2012 ZR1 with NPP. I love the 'loud-when-you-want-it' feature with the M2W addition. I am too old to want to live with a drone on a trip. No more experimenting and messing with aftermarket exhausts for me. (famous last words 
)
)
02-25-2013, 03:13 PM
#5
Le Mans Master
hum I am amazed they your car is loud with all those... oh wait there are no mufflers. Never mind you car should be loud very loud with no mufflers. Haha try route 66 from B & B
02-25-2013, 03:17 PM
#6
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St. Jude Donor '13
02-25-2013, 04:36 PM
#7
Le Mans Master
02-25-2013, 04:43 PM
#8
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Straight pipes are for children who love ample noise, not quality noise.
Get a good exhaust system, first. After you buy the exhaust, then measure the frequencies and use a 1/4 wave resonator tube to get rid of drone
Get a good exhaust system, first. After you buy the exhaust, then measure the frequencies and use a 1/4 wave resonator tube to get rid of drone
My car has NPP.It's ok,I guess. I like BASSANI better but what the hell.
02-25-2013, 04:52 PM
#11
Race Car Tech
We do alot of road trips as well, so I was and am leery about aftermarket exhaust noise. I really don't want a long distance drive ruined by a high decible overbearing racket.
I stuck with OEM, and did the 3/4" hole muffler modification. It's a bit louder, but not enough to ruin a long distance road trip.
Even before I did the muffler mod, I was prepared to buy new OEM Mufflers if it made it too loud.
Now if my car was only for weekends and short trips, then I might think about louder sounding mufflers.
Good luck
I stuck with OEM, and did the 3/4" hole muffler modification. It's a bit louder, but not enough to ruin a long distance road trip.
Even before I did the muffler mod, I was prepared to buy new OEM Mufflers if it made it too loud.
Now if my car was only for weekends and short trips, then I might think about louder sounding mufflers.
Good luck
02-25-2013, 05:00 PM
#13
Pro
Thread Starter
We do alot of road trips as well, so I was and am leery about aftermarket exhaust noise. I really don't want a long distance drive ruined by a high decible overbearing racket.
I stuck with OEM, and did the 3/4" hole muffler modification. It's a bit louder, but not enough to ruin a long distance road trip.
Even before I did the muffler mod, I was prepared to buy new OEM Mufflers if it made it too loud.
Now if my car was only for weekends and short trips, then I might think about louder sounding mufflers.
Good luck
I stuck with OEM, and did the 3/4" hole muffler modification. It's a bit louder, but not enough to ruin a long distance road trip.
Even before I did the muffler mod, I was prepared to buy new OEM Mufflers if it made it too loud.
Now if my car was only for weekends and short trips, then I might think about louder sounding mufflers.
Good luck
02-25-2013, 09:16 PM
#14
Safety Car
Member Since: Jan 2009
Location: Mooresville (Race City USA) NC
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The drone noise you are hearing is entering through the transom and being amplified by the cone shaped reflective rear window of your coupe into the passenger compartment. I could tell you how to fix this, but you would still remain a nuisance by having an illegal exhaust system, which you now seek to exchange for yet another. 
Last edited by laconiajack; 02-25-2013 at 09:22 PM.
02-25-2013, 09:27 PM
#15
Le Mans Master
I have long tubes without cats and B and B route 66 and it was loud. A month ago I install dynamat from the back of the seat to the rear bumper . Drone is cut back BIG TIME. I was almost gonna put back the stock muffler until I installed the Dynamat, IT WORKS.
Last edited by speedraider; 02-25-2013 at 09:29 PM.
02-25-2013, 09:28 PM
#16
Le Mans Master
The drone noise you are hearing is entering through the transom and being amplified by the cone shaped reflective rear window of your coupe into the passenger compartment. I could tell you how to fix this, but you would still remain a nuisance by having an illegal exhaust system, which you now seek to exchange for yet another.
02-25-2013, 09:31 PM
#17
Safety Car
I actually like the drone. Reminds me I'm driving a sports car. Then again mine is not my daily driver. My DD is very quiet. That being said, yeah a complete lack of mufflers woukd be pretty loud.
02-25-2013, 11:33 PM
#18
Pro
Thread Starter
We do alot of road trips as well, so I was and am leery about aftermarket exhaust noise. I really don't want a long distance drive ruined by a high decible overbearing racket.
I stuck with OEM, and did the 3/4" hole muffler modification. It's a bit louder, but not enough to ruin a long distance road trip.
Even before I did the muffler mod, I was prepared to buy new OEM Mufflers if it made it too loud.
Now if my car was only for weekends and short trips, then I might think about louder sounding mufflers.
Good luck
I stuck with OEM, and did the 3/4" hole muffler modification. It's a bit louder, but not enough to ruin a long distance road trip.
Even before I did the muffler mod, I was prepared to buy new OEM Mufflers if it made it too loud.
Now if my car was only for weekends and short trips, then I might think about louder sounding mufflers.
Good luck
02-25-2013, 11:55 PM
#19
Race Car Tech
I didn't drill the 1 1/2 hole as he did. I just drilled the 3/4" hole straight thru. I then used a 1/2 " electrical box plug to cover the hole, and had it welded after I knew that I was satisfied with the 3/4" hole.
http://forums.corvetteforum.com/c6-c...ler-mod-9.html
Hope it helps. At the very least, it's good reading
Here is a pic of the holesaw and the plugs I used. The bag says 3/4 but I used 1/2 plugs.
A 3/4 " plug will fill a 1" hole.
[IMG]
[/IMG]
Last edited by 4SUMERZ; 02-26-2013 at 12:02 AM.
02-26-2013, 12:15 AM
#20
Le Mans Master
The drone noise you are hearing is entering through the transom and being amplified by the cone shaped reflective rear window of your coupe into the passenger compartment. I could tell you how to fix this, but you would still remain a nuisance by having an illegal exhaust system, which you now seek to exchange for yet another.
