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Soundproofing engine noise

MomoJeep

MomoJeep

Basic User
City
Seattle
State
WA
In my never ending mission to give my Scrambler more modern comforts...

Is there a slick (easy) way to sound-proof the engine compartment / firewall to make the engine less noisy?

(I already have a carpeted floor)

thanks!
 
I was surprised how much the raptor liner quieted down the inside of my Jeep. It seems to cut down on that high frequency noise that we get from a Jeep tub essentially being a tin can.
 
I sometimes wear earplugs half way in. Cuts out a lot of road and engine noise....
 
Chamba said:
I was surprised how much the raptor liner quieted down the inside of my Jeep. It seems to cut down on that high frequency noise that we get from a Jeep tub essentially being a tin can.
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haha, yes.. Yes, I also have bedliner and it helps. What I've noticed is after years and years and thousands of miles (and getting older) I tend to drive cruise on the freeway at the bottom end of 5th gear, because it's quiter, but this is not the most efficient rpm.

I wonder if there's a heat/fireproof type material to put on the outside of the engine firewall..
 
MomoJeep said:
haha, yes.. Yes, I also have bedliner and it helps. What I've noticed is after years and years and thousands of miles (and getting older) I tend to drive cruise on the freeway at the bottom end of 5th gear, because it's quiter, but this is not the most efficient rpm.

I wonder if there's a heat/fireproof type material to put on the outside of the engine firewall..
Click to expand...
They make something, but can you afford it, and probably over kill. They make this one out where I work. E87A4848-F3CC-4D75-BB08-46CB9A6D9F38.pngB2C42503-0552-490E-A7FD-2C1CB3AEF1E9.png
 
For cars in the 1930s era it was common to have a jute pad (about 3/4" thick) and then a panel board on the inside of the firewall. It would cut down on the noise but it also retained the heat once it warmed up. I used to get aircraft ceramic insulation, white and 1/8" thick, and cover it with black bowdrill (muslin) and put it under the carpet on antique and classic cars for both sound deadening and insulation.
Some of our CJs had the under hood pad to deaden the sound of the engine. I think Collins Bros sells them.
 
A project I worked on with stationary power generation equipment revealed that a combination of MLV and Rockwool worked very well on deadening sound. Basically, do strips of Dynamat on the sheet steel to "deaden" one frequency and help cancel the "tinning" effect of the sheet steel, then a layer of jute/Rockwool to "absorb" another frequency and heat.

Also check that all of your vibration dampers (engine mounts, trans mounts, crankshaft balancer...) are all in good form. It may also help to add a flex member between your header and exhaust plumbing somewhere to help stop transferred mechanical frequencies in the pipe itself. A chunk of foam cushion squished between the trans and doghouse tunnel can help deaden some gear whine too....assuming you have a manual. Maybe take a look at some of the panels used on the modern engines for noise deadening as well. They aren't very glamorous and tend to make maintenance more of a drag having to remove them, but they do make a difference nulling some of the specific frequencies.

Just whatever you do, bear in mind heat and flammability.
 
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