Making it quiet

[westpole]

I want to cut down on the noise emitting from the engine compartment. What are the best materials and techniques to accomplish that. This is new territory for me and any experience would be appreciated.

[bobconnie]

Lead sheeting to start with and then any other sound reducing material you can find cheaply! It can be a little expensive, but lead works WELL ! Just my 2 cents

[delmarrey]

I lined my motor compartment with 1" thick Vinyl Foam Barrier Composite and I can't hear the motor at all under the cockpit. The vibration is the only thing I can hear.

Sound Insulation - Vinyl Foam Barrier Composite - Soundtec | Fisheries Supply

[model 10]

Lead is so good they even used it on light airplane firewalls. That is a pretty big weight trade off for cabin noise. Lead needs to be covered up, not bare sheet material glued to something. I think it's probably toxic and I removed it from our engine area.

[nimblemotors]

In cars they use very heavy rubber mat to keep the interior quiet.
Amazing what a difference it makes.
Might just see about ripping some out of a junk car.
They sell "dynamat" for this purpose, isn't cheap.
Carpet padding is a cheap substitute.

[GordMay]

Greetings and welcome aboard the CF, westpole.

[sailvayu]

Soundown makes good material for this. Most lead has been replaced with dense plastic material. The best is when the dense material is sandwiched between two layers of foam. This allows it to move some thereby absorbing the vibrations. Make sure whatever you pick is resistant to oil fumes. I have seen a lot of the cheap stuff and materials not meant for engine compartments fall apart making a real mess and it can be hard to remove. Also be careful to block any and all holes or opening into the engine compartment no matter how small. Sound waves particularly the high frequency ones will escape even small openings.

[skipmac]

Originally Posted by sailvayu

Soundown makes good material for this. Most lead has been replaced with dense plastic material. The best is when the dense material is sandwiched between two layers of foam. This allows it to move some thereby absorbing the vibrations. Make sure whatever you pick is resistant to oil fumes. I have seen a lot of the cheap stuff and materials not meant for engine compartments fall apart making a real mess and it can be hard to remove. Also be careful to block any and all holes or opening into the engine compartment no matter how small. Sound waves particularly the high frequency ones will escape even small openings.

In a comparison test of various sound insulation products the Soundown came out as one of the best rated. The test was several years back so there could be new products out that compare but I ordered the Soundown 2" direct from the company in Ft Lauderdale. Am happy with the product and support from the company.

They make a multi layer product with a heavy, lead substitute barrier sandwiched between layers of foam absorbent. Available in different weights and thicknesses.