I've seen people put Dynamat (or similar product) on either the cabin side or the engine bay side of the firewall (or perhaps both sides?). I'm thinking the most effective placement is in the engine bay, as it will both reflect heat and dampen sound where as in the cabin it will primarily dampen the sound but the firewall itself will not be isolated from absorbing heat.

From a strictly cosmetic standpoint, there's nothing quite as nice looking as a freshly painted firewall, though the "Dynamat look" is kinda cool too. I'm doing a V8 conversion, but the principles should apply either way. I'm near the high desert in SoCal, so heat management is an important consideration in these parts.

Andys

For maximum effect, they have a hood liner specific product to put on the firewall side, and use a layer or two of regular Dynamat on the inside of the vehicle.

AA offers a kit that includes two layers. The first is the lead foil dynamat, and the outer layer is the dynamat material that has an outer surface that looks like the original liner. These are die-cut to just fit right into the engine bay. I was pleased with my application of their materials, and it looks really nice. Just clean the firewall and stick it in. Not much more expensive than buying the real dyanmat from the typical vendors. Of course there may be other sound deadening materials besides dynamat that may work as well. I browsed through all the literature posted on sound deadening materials, and could find references ranging from roofing tar from home Depot on the bottom, to Dynamat at the top. In the middle were products such as fatmat, etc. JoeO

Performance Products has an engine bay mat also. With a V8 I think I'd do both!

Painted firewalls do look good, but you will need the barier not just from the heat but sound as well. At least that seams to be the case with my v-8 project. I endedup building a Ghetty grill also to help with the heat. The one thing I noticed the most was the "resonation" of the exhaust at idle and low speeds. I replaced both inside and outside with like new stock padding but it still gets a bit noisy in the cab.

Thanks for the reply's.

My firewall is very slightly modified to clear the tensioner and belt on my LS1. I did this in order to retain the stock water pump (and two access panels). As such, a pre-made firewall kit will not work out in my case.

I agree that logic points to Dynamat in the enine bay, so I'll probably do that. I'm going to check out Rick Evan's car at the GAF tomorrow, as he has Dynamat (or similar product) done in that way.

Since I wish to have a quieter cockpit (or should I say "less noisey") for my V8 conversion, I chose 3 chambered Flowmaster mufflers over the more commonly installed two chambered one's. Their main advantage, according to Flowmaster's db chart, is significantly less interior noise and resonance than the two chambered mufflers. Being larger of course makes them a difficult fit, but fit they did; just barely.

Andys

I can tell you that I heard my exaughst (very loud ) before the Dyanamat and after in the engine bay, and I can tell you, it definately works. I'll put it to you like this, Before the Dynamat , I almost put in earplugs, After the Dynamat, I could talk on a cell phone, with the targa top off, on the freeway, and hear just fine, on a low volume phone !!!

Hey Andy,

I love the look of a clean, shiny freshly painted firewall...It sets off the inside of the engine bay...But...

The problem is, you build in an echo chamber to enhance the vibrations and noise...

Don't use Dynamat either...There is another product out there Called "Be Quite", (www.b-quiet.com) that has the same db #'s and yet doesn't say "Dynamat" "Dynamat""Dynamat""Dynamat""Dynamat""Dynamat""Dynama"
"Dynamat" "Dynamat" "Dynamat" "Dynamat" "Dynamat" "Dynamat" "Dynamat"
"Dynamat" "Dynamat" "Dynamat" "Dynamat" "Dynamat" "Dynamat" "Dynamat" all over your engine bay...It's also cheaper and you can order over the internet...

Lay it like shingles on a house, start at the bottom and layer it over the top...That way water will flow over and shead off instead of finding a leak path, pocket water then rust another hole in your firewall...

Sure makes a difference in the interior noise...For 25cents, a ride, I'll take you for a spin...

2-OH!