for awhile i've been planning on adding dynamat or fatmat to the cabin of my FD to cut down on noise and heat transfer. i'm thinking more and more about saving weight while building my car as well so removing the oem sound deadening is on the list before putting in the dynamat material.

i was searching around the site and found that the oem sound deadening weighs ~25 lbs. is this correct? is that for just the hard material? also, the thick rubber mat that runs down the firewall to the floor, was its weight part of the ~25 lbs or is that separate from the hardened noise damper on the floors? for those of you that have removed the sound deadening, did you remove the rubber mat as well? as long as i'm adding the dynamat i don't see where this would be a bad idea. my interior has a foul, kinda moldy smell to it and i plan on pressure washing the carpet to reuse but, as far as the backing, i'm pretty sure that's gonna have to go.

lastly, which method works best for the removal? i've seen where many use dry ice successfully. it looks to be the cleanest solution. i've also seen the heat gun and scraper method. that doesn't look to be as clean but, i've seen on other cars where some of the dampening just won't come off with the dry ice so the heat gun and scraper had to be used. either that or a wire wheel. i'd really like to keep the paint in good shape as much as possible. yes i know it's going to be covered up anyway but, still.

it seems like there was something else i wanted to ask but i can't think of it at the moment. anyway, input is appreciated. any tips, tricks, or short-cuts would be great. on a side note, i'll be removing the dash to remove the rubber mat and install the dynamat and also to get rid of some wiring i'm not going to need but, is there anything else i should do while it's out? thank you.

 

IMHO I think you should probably leave the factory stuff in and maybe add some lightweight stuff on top and or in spots that it isn't currently located.

You might be able to save a little weight by taking out the factory stuff and replacing it with aftermarket, but it is a whole lot of work and in the end you will probably end up about the same weight and noise level assuming you are using the heavyweight stuff. I don't think the aftermarket lightweight stuff is necessarily better than the factory stuff, it looks like a thin layer of dampening material with an overlay of foam.

Another option is to fill voids in the car with smallish bags of polyester fiberfill. There are not tons of box sections in the car, but some behind plastic trim panels in the rear trunk area., and behind the rear set side trim panels and you could stuff some in other places. Polyester fiberfill is used in speaker systems to reduce internal vibrations and slap echo within the cabinets. If the polyester is put in bags first it won't absorb any moisture and will be easier to remove if you need to.

I once picked up a bunch of fiberglass insulation in my CRX and had the hatch open since the back hatch area was full up. Even with hatch open, the car was dramatically quieter than it normally was with the hatch closed, the fiberglass did a great job of absorbing sound.

 

Have you looked into a sound deadening coating like LizardSkin? It may be labor and cost prohibitive for you, but I think in the end, it is the best option as far as weight and sound reduction goes. You'll have to gut your entire interior for it. Here is a good example https://www.rx7club.com/v-8-powered-.../#post10788140

 

I'm alittle concerned about noise level but most of my concern is heat. I'm going LSx and I read even with the rotary the heat was an issue inside the cabin. I'm hoping to drastically reduce the amount of heat transfer to the cabin. Reducing noise is a plus. From what I've read and heard, dynamat works wonders for noise and heat.

 

LS1 ought to produce less heat than a turbo rotary anyway. Most everything short of the very sun itself does.

 

I actually check out your thread a good bit. Nice work man. Need updates tho. Also, where'd you get your 929 master cylinder?

Another reason I'd like to go ahead and remove the oem stuff is because a friend of mine works at a Health Foods where they regularly throw out all the dry ice and he said to let me know when I want it and he can get as much as needed. Since the dry ice is free and I don't mind hard work, I thought it'd be a good idea before I put the dynamat or fatmat in.