Noise insulation, Engineer types opinions needed Options

[nivekdodge]

Just a thought

There's another thread today discussing using perlon for the back pad and if it was quieter or not. Something I've notice is Some GM hood have their inner surface looking like a golf ball. There are 3" round divots and when asked about it I was told it reflects the sound back to the motor and that kills the sound.Anyone know if there is truth to this?

This would of course be in the engine compartment.

Kevin

[Mikey914]

Just a thought

There's another thread today discussing using perlon for the back pad and if it was quieter or not. Something I've notice is Some GM hood have their inner surface looking like a golf ball. There are 3" round divots and when asked about it I was told it reflects the sound back to the motor and that kills the sound.Anyone know if there is truth to this?

This would of course be in the engine compartment.

Kevin

Perlon will offer little sound deadening effect.

The only way to "kill" noise is to
1- have active noise reduction that creates a sound wave opposite the sound
https://www.youtube.com/watch?v=oVZEtDyTdBI
2- provide a barrier that will absorb the sound ie. dyno Mat or a product similar.




The problem is that when you eliminate noise from the engine compartment, you will get the road noise. There are really too many sources in a 914 to have a "quiet" ride.

So your time and money spent have decreasing returns.

The heavy "tar" mat that is factory works pretty well. If you need to have perlon for an aesthetic you are looking to achieve you could take a back pad and cover it with perlon. Either a stripped-down stock one or one of these-

https://914rubber.com/thermal-formed-3-piece-back-pad-core-1



Matt used this on his car