sound deadener. How much ?

[Houston Taylor]

Anyone know about how many square feet of sound deadener i would need to do the floor, doors, roof, and trunk in a 78 trans am ?

[Gene-73]

Depends on your definition of "sound deadener".  There are different materials and combinations of materials on the market for controlling vibration, noise, and heat.  The amount of material you'll use depends on how you address each of those three areas.

The overall square footage in the cockpit of a second gen is around 120 sq ft for the floor, firewall, trunk wall, package tray, wheel wells, doors, and roof without T-Tops. 

If you are looking for only the butyl rubber type product that adhesives to the sheet metal to cut down on resonance and vibration, a good rule of thumb is 25% coverage.  Using the number above, that would mean 30 sq ft.  Some people go 100% coverage with this type of product and call it done, but it's better to do the 25% coverage and spend the extra money for an additional layer of closed cell foam and mass loaded vinyl at 100% coverage in key areas.

A good primer on this topic can be found at https://www.sounddeadenershowdown.com/

[Houston Taylor]

I was thinking of getting this kit from raamaudio any opinions on this ?

http://www.raamaudio.com/package-2-30-sheets-of-raammat-bxt-ii-56-25-sq-ft-and-4-1-2-yards-of-ensolite-foam/

[roadking77]

No idea what other cars sound like, but i have a warmed over 400, with raIII manifolds, pypes violator exhaust. Driving down the road all i hear is engine! To me that's not really a bad thing but my point is that if you want a quiet ride put as much sound deadener as possible in it. I used the factory replacement which is basically very heavy weight tar paper on the floor. I put 3/4" dynamat on the inside rear wheel wells and the backseat trunk divider. Def not enough!

[Houston Taylor]

I know its a muscle car and im going to hear some exhaust and engine, not looking for luxury car quiet but im about to pull the interior to have it redone so if figured now is the time to add something. Especially to the doors and roof 

[DD78TA]

When I did mine I used a couple rolls of HVAC material I purchased from Lowes or Home Depot that looks a lot like the stuff in your link. It was maybe 3/16 foam with a real heavy bright aluminum? backing, the foam part stuck down. And my car had a heavy roof single type mat in it as well that I reused on top of the HVAC material. I was more after keeping heat out than noise. I was getting a lot of heat through the toe board and firewall area. I covered that area real well and plugged all the holes. Floor and console hump area got covered too of course. And I sealed off the kick panel vent areas real well.

It's hard to say what impact it had for sound deadening as there was about a 2 year span while I restored the car, so it's hard to compare. But I can say it helped a lot with keeping engine and exhaust heat out.

I want to say welding in subframe connectors and adding solid body mounts did more for quieting my car ride down than anything else I did.

[Gene-73]

Before I tore it apart, my car was the same as roadking, couldn't even hear the radio over all the noise.  So my goal is to install the most soundproofing possible but without spending a fortune.  When I first started researching this topic I found it hard to figure out what to get based on the marketing. 

I found that these sources were the most informative.
https://www.sounddeadenershowdown.com/
http://www.myturbodiesel.com/wiki/soundproof-car-diy-to-reduce-noise/
https://www.youtube.com/watch?v=I5E9mjI3y1E

I've yet to find a good example of someone who measured before and after with an audio meter, although the video above comes close.

Your link is for the RAAMmat BXT II which is a stick-on butyl rubber (for deadening vibration and resonance) and aluminum foil (for heat) with a second product of foam that you stick on top of the butyl. For the most effectiveness you still want a third layer that doesn't stick on, just lays on top, of mass loaded material (for noise). This is typically a vinyl but you can also purchase a carpet kit for your car that includes the mass loaded layer.  Keep in mind these products, except for the foam, will add quite a bit of extra weight.  The butyl rubber and mass loaded vinyl can each add up to a pound per sq ft of material used.

I've only bought (not installed yet) the butyl/aluminum sound deadening layer.  When I researched it last year I compared Dynamat, Summit brand, RAAMmat BXTII, Stinger, Fatmat, and Noico.  The least expensive per sq ft was Noico by a considerable margin, with Dynamat the most expensive (the list is in order of cost).  They all have equivalent product as far as I can tell, but when you compare make sure to look at the thickness/weight of each product.  I've yet to purchase the foam/MLV layer(s) but looking at either a single product that combines both, or buying just the closed cell foam and a new mass loaded carpet kit.