Hmmm... my results were better. I finished "nerfing" my Fiero yesterday. I filled the B-pillars, A-pillars, upper and lower doorframes, console supports, front and rear roof supports, and the bottom of the firewall... basically every frame member in the cabin. Here are the before and after results:

BEFORE -- 71dBA / 86dBC
AFTER -- 61dBA / 83dBC

Keep in mind that this is with a bare interior, save for the driver's seat, instrument pod, and door panels... and the engine at idle.

The car sounds more solid going over bumps and stuff. Instead of a hollow, "echoey" sound, it's more of a solid "thunk". Some of the smaller stuff (pebbles and small cracks in the road) aren't even audible anymore, although I can still "feel the road" through the chassis. Overall, I'm very pleased. I had to use alot of foam, though. I went through 9 cans of "Great Stuff" expanding foam. I can't wait till the mass-loading material arrives.

[This message has been edited by Blacktree (edited 05-20-2004).]

I run a Borla system with Sprintec manifolds...and no cat.....a straight headpipe instead....sounds GREAT....Like a V-8...I like it!

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1988 Gary Tucker (GT)

Idle, in gear, meter 6" above console pointed forward, halfway between rear storage lid & shifter, 55 dBA slow.

The vinyl sheet (mass-loading) arrived a couple days ago. I've been busy installing it, during my free time after work. So far, I have one layer on the top half of the firewall, the center of the roof, and the back halves of the floorboards. I decided not to install any on the bottom half of the firewall, since the foam seems to be doing a good job of deadening that area.

I still need to finish the first layer on the floorboards, and then hope to have enough material to install a second layer. I won't be putting a second layer on the firewall or roof. Here are a few shots of my progress:

FIREWALL

FLOORBOARD (passenger side)

ROOF

So far, I've used about 1.5 sheets (27x40") of mass-loading mat. I bought 3 sheets at about $23 each from Parts Express. Before calling it a day... SOUND CHECK!

As with my previous sound checks, the interior is mostly bare (save for the driver's seat, instrument pod, and doorskins). The meter is held about 10-12" above the fuel tank hump, with the mic pointed forward. The meter is set to "slow" and "max". The engine is warmed-up, running at idle.

RESULTS: 60dBA / 81dBC

Getting better...

edited for typo

[This message has been edited by Blacktree (edited 05-23-2004).]

My God ! Looks like the damn SPACE SHUTTLE !!! Good work man! Do you want to do another one?

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1988 Gary Tucker (GT)

[This message has been edited by GARY TUCKER (edited 05-23-2004).]

quote My God ! Looks like the damn SPACE SHUTTLE !!!

Now that you mention it, yeah it does.

I had to install the vinyl in strips, because of all the funky contours in the floorboards and firewall. It made marking and cutting the irregular shapes easier, and minimized the chance of trapping air bubbles.

Would I want to do another one? If the price is right. It's one of those pain-in-the-butt jobs.

I've finished the mass-loading. And I won't be installing any more spray foam. So the following results can be considered as my "final bare interior" results.

RESULTS: 58dBA / 79.5dBC

This is with two layers of vinyl on the back halves of the floorboards and gas tank hump (between the forward seat support and the firewall), one layer on the top half of the firewall, one layer on the front halves of the floorboards and gas tank hump, and one layer on the center of the roof. I've also installed some 1/4" foam rubber on the center of the roof and the top half of the firewall. This will give the firewall cover and the headliner something soft to rest against.

Here are a couple shots:

Now I get to start working on the custom interior and sound system. I'll post details in a seperate thread.