Sound Proofing

[JeremyG]

Hi - I’m looking to soundproof my engine bay.  The engine is under the floor in the cockpit which has removeable ply boards.

so I had a look on ASAP and the proper stuff looks flipping expensive.  I’d have though some 25mm or 50mm celotex would do the job nicely glued on to the bottom of the flooring.

anyone got any wisdom on this?

jeremy

 

[Guest]

2 minutes ago, JeremyG said:

Hi - I’m looking to soundproof my engine bay.  The engine is under the floor in the cockpit which has removeable ply boards.

so I had a look on ASAP and the proper stuff looks flipping expensive.  I’d have though some 25mm or 50mm celotex would do the job nicely glued on to the bottom of the flooring.

anyone got any wisdom on this?

jeremy

 

You may already know this but sealing "gaps" is as important as covering the boards with sound proofing material.

[Smoggy]

Celotex isn't that great for low frequencies that you tend to get from diesel engines, the quietlife stuff is pricey but very good.

It's one of those jobs where heavy is better at absorbing noise.

[JeremyG]

Sure - that makes sense - thing is the boards have to be easily removable so there will inevitably be some gaps.

[ExSurveyor]

Celotex is aimed at thermal insulation,  a different beast to transmission of sound. Being solid it will still transmit sound.

Go for a proper sound deadening system but look to automotive suppliers and layer it. 

[TheQ]

Those of us in the Land Rover world, who have money tend to use FATMAT (US site but you can get it in the UK https://www.fatmat.com/ 

Those of us in the Land Rover world, like me, who have little money, use Flashing tape which is almost Identical, costs a lot less, but doesn't come in Huge sheets.  https://www.diy.com/departments/building-supplies/roofing/flashing-tape/DIY570203.cat

This then is covered in 10mm or 12mm EVA rubber camping mats. it's very effective.

 Remember that if you are going to hang anything over moving or hot parts, you will need a Mechanical way of holding the sheets on not just glue.

I'm lucky sitting in my boat is a 8X4 sheet and a half of Jet engine test bay insulation, left over from... err insulating a jet Engine test bay. But at nearly 4 inches thick it was too thick to use on the Landrover..

Its made of two sheets of very fire proof foam rubber with a thin sheet of perforated lead stuck between. This I hope to fit this summer.

 

[scaniaman]

Try "noise killer acoustics" Oldham 0161 652 7080

[Simon]

Not sure whether it would suit your access panels or boat but carpet underlay is a great sound insulator, especially the super Duralay rubber crumb type.

One way to use it would be to roll it out on top of your cockpit floor, cut to shape then fully stick a carpet to the top of the underlay, don't stick the underlay down, its own weight will hold it in place in cockpit size areas.  when you want to get under just roll the whole lot up as one.

[Labrador]

3 hours ago, JeremyG said:

Hi - I’m looking to soundproof my engine bay.  The engine is under the floor in the cockpit which has removeable ply boards.

so I had a look on ASAP and the proper stuff looks flipping expensive.  I’d have though some 25mm or 50mm celotex would do the job nicely glued on to the bottom of the flooring.

anyone got any wisdom on this?

jeremy

 

You get what you pay for, it's a matter of discerning which of what you call 'flipping expensive' is best value for money.

[Wildfuzz]

What do they use in sound studios, always looks like empty egg boxes to me? Surely though with an engine bay fire suppression needs to be considered. The heavy workshop mats are a closed cell foam and very heavy but would be at risk in a hot environment or touching a manifold or similar.........

[LondonRascal]

This is complicated. Because sound moved through air but you need air and a lot of it feely to move into and out of your engine room so the engine can breath freely and it will take a lot of work to reduce a small amount of perceived sound in decibels.

Here are some helpful links though:

https://www.marinescene.co.uk/category/112/acoustic-sound-insulation/

http://www.yachtingmonthly.com/archive/marine-engine-soundproofing-527

https://www.boatsandoutboards.co.uk/Owning-a-Boat/green-boating-how-to-soundproof-your-engine-room/50

 

[ZimbiIV]

Ear plugs?

paul

[Guest]

1 hour ago, ZimbiIV said:

Ear plugs?

paul

Or sails?

[finny]

I did my Hampton engine bay with quiet life 50 mm and it did a fairly decent job cut to size and spray glue on  - i would guess around a 50% noise reduction and was happy with that .also what i did notice further down the line was that i had a better smelling engine bay all them service and maintenance jobs like oil and grease overspills could easily be wiped off the foil insulation - we had that honeycombe foam with a lead barrier before it stunk of oil and it wasnt that good but like all things you get what you pay 

 

finny   

[TheQ]

The last type shown in the video has a great similarity to the fireproof jet engine bay stuff I have..

[Smoggy]

44 minutes ago, TheQ said:

The last type shown in the video has a great similarity to the fireproof jet engine bay stuff I have..

It's the lead loaded barrier that does most of the work for deep diesel engine rumbles, the thin layer is to stop it transmitting straight through and the thicker foam takes out mostly higher frequencies.

I have quietlife under my engine boards and it does do a good job till the turbos spool up, I dread to think what it would be like without.

[TheQ]

yep I'd agree with that...

[JeremyG]

Thanks for all the tips.  Glad I didn’t waste time and money with the celotex route...