bonnet insulation

[grodob]

I am in the process of cleaning the bonnet underside.
The sound insulation had been pulled off before I purchased the car, I am left with the sticky backing now.
On a previous 944 that I had I removed everything and polished up the underside of the bonnet, but always wondered if the sound insulation actually made some difference to noise levels or not?
Just wondered if there were alternatives to the rather expensive porsche insulation?

 

[GlennS]

Porsche didn't seem to think there was much point as they stopped fitting it from the late 80's onwards. Can't remember the exact model year.

 

[craiginuk]

Is that same for turbos too? I thought there was some heat shielding properties there too or am I mistaken? I did notice an increase in engine noise when i removed mine for a short period.

 

[GlennS]

ORIGINAL: craiginuk Is that same for turbos too?

I presume so. The under-bonnet insulation parts are listed in the parts catalogue for model years 1985-1988 but not for model years 1989-1991. That catalogue covers the turbo as well as the NA models. Certainly, my 1990 S2 never had the insulation.

 

[Lowtimer]

Nor did my 1990-build Turbo. You can do without it quite happily.

 

[craiginuk]

Sorry to hijack original post but I have another question. Mine has an aftermarket high temp matting fitted with a silver reflective coating. Would this keep the temp under the bonnet hotterbthan it should be? And would this combined with a k and n induction kit mean I am drawing in much hotter air than I should be?

 

[Frenchy]

Yes, turbos like cold air, the colder the better hence Porsche vented the air inlet to under the front wing.

 

[Gavin944s2]

i have an origonal 1992 spec 44s2 , there no insulation under the bonnet other than the distributor cap protector. IMO they do not need any, there scorchers under the bonnet.