Hey guys,

Picked up a 90 Iroc with a LSx T56 swap. There is way too much engine noise in the interior cab. I found the pass-through at the firewall for the computer had space around it so I filled that, but still way too loud. Car also had the carpet swapped.

Anyone done any work at reducing engine noise in the interior.

Thanks!

 

my only suggestion would be to insulate the body more. Pull the carpet and dynamat (or equivalent) around the firewall and under the carpet. that should quiet it down a lot. also make sure your headers are tightened down good. An exhaust leak could make it quite noisy under the hood.

 

I think the long tubes and true duals add to the problem, but the it seems as too much is passing through the firewall.

Any tried to separate the engine noise from the cabin?

Asim

 

Check under the carpet that is up against the firewall. when they replaced the carpet they may not have installed the firewall insulation pad. I'm running a large cam 246/256 @ .650 lift, LG 1 7/8" long tubes and 3" exhaust with no cats on my corvette and the sound in the cabin increased a bit. I installed an insulation kit similar to dynamat and it knocked the interior noise down almost 20db and my console and cup holder don't get hot anymore. Not to mention I cannot here the clutch noise from my twin disc anymore.

 

also, what size headers and exhaust do you have on your car? What LS motor are you running and what mods does it have? Depending on the size of the motor and mods your headers and exhaust may be too large. If that's the case the abnormal increased noise could also be header/exhaust noise from the exhaust gases resonating inside of the tubing instead of being pushed out quickly enough

 

No4Play I think you're on to something.

I have the same clutch chatter noise and heat getting into the cabin.

What insulation did you use?
Asim

 

Reflectix and it works great. Very inexpensive (you can get enough to do 2 cars for under $25) Get the 25" wide roll. Put it in with 3M adhesive. I used #77 Adhesive and worked well. Just take your time and cover everything, from behind the seats all the way up under the dash as far as you can get, AND the tranny hump.

 

No4Play it's amazing how similar our cars are.

My sig would look:
1992 RS 25th Anv
LQ4, LS2 heads
Comp cam and springs
true duals
C5 brakes
2005 C5 Wheels

 

Very similar! You have a few more cubes then I do, lol. This car is my fiance's so i figured I would try to keep it under 500rw.

 

I think its safe to say I found the source of the noise. I took the center console out first with the intent of pulling the front seats as well. Didn't have to go past the center.

Take a look at the hole cut for the shifter. I used roofers aluminum padding to cover and seal.

Car is all of sudden normal.

 

that'll do it lol! glad you found the source and fixed it!