reducing drone

m4a1mustang · 11-27-2009, 10:43 AM

Adding sound deadening to the interior of the car is the only real option. Be advised it is going to take a significant amount of quality mass-loaded volume to be able to block the drone and you are going to end up adding, at minimum, 50 lbs to the car.

Applying it to the hatch alone won't do much because there is no deadening in the rest of the car so it just finds other ways to get through... you'd have to do the whole floor and hatch to make a noticeable impact.

Since you have the 12" resonators you might want to consider swapping for the 18". You'd probably be able to resell your 12" so you might not take that much of a hit.

I have the 18" and the only real annoyance is with highway driving if I need to be applying throttle. Flat roads are fine, but throw some hills and mountains in there and you are constantly dealing with that noise. Everywhere else I think the sound levels are fine.

Nikon FM · 11-27-2009, 10:54 AM

The treatment depends on if the drone you hear is structural or airborne noise related. If structural, adding damping at the attach points of the exhaust would help minimize the energy getting into the structure. If airborne then the mass addition to the interior panels is the way to go only after identifying which panels are the greatest contributors. If most of the airborne noise is vibrating your windows you are pretty much screwed unless you can change the modal characteristics of the window ("add a heavy tint layer"......joking).

Notice all the "ifs". Careful effort identifying the "source-path-reciever" will enable the least amount of weight addition.

You gained HP why throw some of that goodness away by adding unnecessary weight?

Modshack · 11-27-2009, 11:40 AM

Quote:

Originally Posted by m4a1mustang

Adding sound deadening to the interior of the car is the only real option. Be advised it is going to take a significant amount of quality mass-loaded volume to be able to block the drone and you are going to end up adding, at minimum, 50 lbs to the car.

.

My Corvette had a big plastic tub sitting right over the Mufflers. After installing headers and HFC's I had an issue. It resonated like a Bass drum. On Vette's the drone RPM is 16-1800 RPM's which is easy to work around with the next lowest gear selection. Regardless, a liberal coat of Second Skin Damplifier helped quite a bit. Maybe 25-30 lbs worth. Some Z guys have done this...Check over in the Audio section.

6MT · 11-27-2009, 03:18 PM

Quote:

Originally Posted by Modshack

Yee-Haaawwww!! Let's have a bar-b-que!! Looks like you can throw the chicken right on top of that foil!

(sorry)

11-27-2009, 10:43 AM	#1 (permalink)
m4a1mustang A True Z Fanatic Join Date: Feb 2009 Location: Northern VA Posts: 55,385 Drives: on two wheels Rep Power: 6963	Adding sound deadening to the interior of the car is the only real option. Be advised it is going to take a significant amount of quality mass-loaded volume to be able to block the drone and you are going to end up adding, at minimum, 50 lbs to the car. Applying it to the hatch alone won't do much because there is no deadening in the rest of the car so it just finds other ways to get through... you'd have to do the whole floor and hatch to make a noticeable impact. Since you have the 12" resonators you might want to consider swapping for the 18". You'd probably be able to resell your 12" so you might not take that much of a hit. I have the 18" and the only real annoyance is with highway driving if I need to be applying throttle. Flat roads are fine, but throw some hills and mountains in there and you are constantly dealing with that noise. Everywhere else I think the sound levels are fine. __________________ - Steve Zs & Coffee - Saturdays at 10AM in Fairfax, VA and Columbia, MD (Click the banner!) LIKE us on Facebook!

11-27-2009, 10:54 AM	#2 (permalink)
Nikon FM Track Member Join Date: Jan 2009 Location: Snoqualmie WA Posts: 973 Drives: 03 996TT Porsche Rep Power: 607	The treatment depends on if the drone you hear is structural or airborne noise related. If structural, adding damping at the attach points of the exhaust would help minimize the energy getting into the structure. If airborne then the mass addition to the interior panels is the way to go only after identifying which panels are the greatest contributors. If most of the airborne noise is vibrating your windows you are pretty much screwed unless you can change the modal characteristics of the window ("add a heavy tint layer"......joking). Notice all the "ifs". Careful effort identifying the "source-path-reciever" will enable the least amount of weight addition. You gained HP why throw some of that goodness away by adding unnecessary weight? __________________ Buddy Revell: "One man's sooner is another man's later"