sound deadening

[peanut]

In an effort to cut down on noises emanating from my engine, I have been turning up the radio but lately its just not cutting the mustard so I'm looking for an alternative to neutralize the ticking injectors, valve shims and squealing alternator bearing that turns heads and announces my arrival from 1/4 mile away.

Did the 944S2 ever have any sound deadening material fitted to the underside of the bonnet at the factory ? Mine has never had any so I assumed it never did.
If I were to fit some what type of foam and thickness would you recommend ? I was looking at some polyethelene closed cell foam about 5-6 mm thick ...what think you ?

 

[944Scott]

I was going to ask the same question for the turbo? I have seen some with it fitted but I'm unsure as to whether it was a factory fit.

 

[zcacogp]

I think they fitted it to earlier models but not to later ones.

Bear in mind that the area just under the bonnet will get very hot indeed after a spirited run so whatever you fit will need to be very heat-proof. And the glue you attach it with will need to be similarly rated.

I suspect that the panels have a Porsche part number but that will be the most expensive way of buying them. Something from one of the 'tuning' catalogues would be a good place to start, although there will be doubtless cheaper alternatives elsewhere.

Oli.

 

[vitesse]

Both our 924S's have factory fit waffle type foam sound insulation pads

 

[graham.webb]

Colin's correct...I think 924s had it (early problems with heat gain in the US affecting the EFI?). Some of the American websites sell it (Pelican?). My S2 doesn't have it either. I wouldn't mind something like that to prevent condensation collecting on the underside of the bonnet, then dripping off and corroding the strut mount fixings and the brake servo!!

 

[jasonp]

both my s2s had the foam underneath the bonnet,,,
large foam square on the red car and a smaller foam square on my present blue s2,,,
maybe they were not fitted to the turbos????,,,,,,,jasonp

 

[PSH]

I can state that the foam was certainly fitted to the early turbo's, IIRC you can get replacements from Porschshop...I'd try the main dealer first, though.
A word of warning re- alternator with failing bearings....I have a theory that this and the A/C unit bearings failing could be the cause of crank pulley's coming loose...I say this as when my pulley fell off both alternator and A/c bearings were toast and perhaps the drag matched the frequency of the pulley leading to it coming undone...it's a possibility and so I say be careful..

Pete

 

[Paul 290T]

my early turbo had "egg box" style sponge fitted from new. This disintegrated around 2011. I bought new pads from classic9leathershop.com. After running the car with no pads then fitting the new ones I can confirm the do noticeably quieten the car down.

Choose their 1/4 inch not 1/2 inch version if you don't want some engine ancillaries to be embossed into the new lining materiel.

And make sure the engine is cold before you apply the spray adhesive, or else the solvent evaporates too quick and balloons up the new lining.

 

[GlennS]

Did the 944S2 ever have any sound deadening material fitted to the underside of the bonnet at the factory ?

The under bonnet sound deadening material was discontinued after MY88 for all 944s, so no S2 had it as "factory" although they did have a vestigial square of foam under the bonnet just over the distributor... Any MY 89 onwards cars that had the sound deadening pads probably had them retrofitted by owners at some point.

 

[peanut]

thanks for the replies....very interesting. I hadn't thought about the potential increased under bonnet heat issue .
Something that has occurred to me though is the extra weight might bring the bonnet down on me bonce .
I might have a look for some thin adhesive backed acoustic material and give it a try.

 

[Paul 290T]

Peanut, don't worry, based on my car the added weight wont collapse the bonnet struts.

Given that the foam was fitted to turbos, which because of their glowing orange turbocharger and its uninsulated crosspipe, definitely put more heat into the engine bay than a normally aspirated S2 without issues - you needn't worry.

If you go for any material on acoustic grounds thin might not reduce the sound level much.

The main thing to be concerned with is the material you choose is not one that will catch fire when it picks up engine heat.

 

[Paul 290T]

Peanut, don't worry, based on my car the added weight wont collapse the bonnet struts.

Given that the foam was fitted to turbos, which because of their glowing orange turbocharger and its uninsulated crosspipe, definitely put more heat into the engine bay than a normally aspirated S2 without issues - you needn't worry.

If you go for any material on acoustic grounds thin might not reduce the sound level much.

The main thing to be concerned with is the material you choose is not one that will catch fire when it picks up engine heat.