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Thread: Under hood insulation/soundproofing

  1. #1
    Registered User madkaw's Avatar
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    Default Under hood insulation/soundproofing

    Couldn't find much searching under this subject. I don't even know if Datsun did this type insulating from the factory. Love to hear from someone that has insulated under the hood for noise and what their results are.
    I would think a barrier between the hood and the valve cover would suppress a lot of mechanical noise and make for a quieter engine. Don't get me wrong, I like hearing my engine, but would prefer to get rid of any metallic sounds and here a more subdued power-if that makes sense.
    I know some folks are worried about adding weight, but I'm not concerned. Maybe I need to step up the firewall insulation with some dynomat or something.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Nova Scotia,Canada,Earth Blue's Avatar
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    Most drown it out with ITB's or Webbers/Mikunis/Solex
    There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply.
    The person who buys on price alone is this man's lawful prey.


    John Ruskin (1819 - 1900)



    ZCars in Eastern Canada seaport ready for shipment to Europe

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  3. #3
    HS130-150591 4/79 zbane's Avatar
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    You could always look into the under hood insulation that's on modern cars... Sure, that's all fitted to the make/model, but if you could find it in a bulk/moldable form...
    An added benefit of using the modern stuff is that, in addition to deadening engine noise, it's also a fire retardant/suppressant.
    David
    _____________________________________
    HS130-150591, April, 1979-280zx
    2001 Infiniti I 30

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    There are many aftermarket sound suppression / heat shields available. I've never been a fan because I want the heat out from under the hood and feel like anything applied to the hood would serve to contain it.
    1977 280Z - Sold 10/1986
    1978 280Z - Current and forever

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    The dynomat on the fire wall plus the tranny hump should quiet it down some ,I have that on mine and it is a very comfy cabin
    Last edited by 72 OJ; 06-15-2012 at 09:35 AM.

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    Z geek at large FastWoman's Avatar
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    Two problems come to mind. First is that there isn't a lot of room between the engine and hood. Second is that the engine compartment gets rather hot even as it is, especially in the pre-'77 unvented hoods. Insulation would make the problem worse.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Registered User Travel'n Man's Avatar
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    Quote Originally Posted by Blue View Post
    Most drown it out with ITB's or Webbers/Mikunis/Solex
    Agreed! Triples are a must - with beer and carbs!! Triple Karmeliet and Mikuni's are my pick!
    Life's a journey; enjoy the ride!

    Mitchell
    L28 - N42 Block w/Flat tops - N42 Rebello Head & Cam - Triple 40 PHH Mikuni's - Headers - Recaro Seats -
    R180 3.9 Diff - Close Ratio 5 Speed - Toyota Vented Brake Upgrade w/ Porterfield High Performance Pads & Shoes

    1972 Datsun 240z
    HLS30-75040


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    I used aluminum foil bubble wrap to insulate a Subaru hood. I was trying to keep heat IN, in the winter the thing took forever to warm up.

    I used hot melt glue to attach the bubble wrap, now and then I'd have to go touch up the glue.

    Cheap, worked well, and easy to remove if you decide you don't like it.

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    Nova Scotia,Canada,Earth Blue's Avatar
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    For any winter car, you can block off the front of the rad and get a higher temp. thermostat to help stay warmer and faster. A block heater can help too.
    There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply.
    The person who buys on price alone is this man's lawful prey.


    John Ruskin (1819 - 1900)



    ZCars in Eastern Canada seaport ready for shipment to Europe

    http://ZSportCanada.com


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    Rust Free'ish zKars's Avatar
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    Other than firewall sound deadening, the one item that made a remarkable difference to engine noise for me, was the addition (replacement actually) of the weatherstrip across the lip where the hood latch is located. After applying this strip along with an overall WS replacement binge some years ago, I remember getting in my triple powered z for a drive, pulling away, and thinking "oh oh somethings wrong! The motor sounds wrong and gutless!" Nope, the noise coming back to me through the hood/cowl gap was sealed by that strip!
    -----------------------------------------
    Jim
    73 240Z HLS30 149331
    69 510 PL510 77603

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  11. #11
    1978 280Z (stock) TomoHawk's Avatar
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    If you put on anything to keep the noise in, the heat will stay in too, so you'd need to get the air flowing through there, which means the splash guard and a fan shroud is in order.
    Drive Responsibly.
    enjoy classic Rock music.

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    Quote Originally Posted by zKars View Post
    Other than firewall sound deadening, the one item that made a remarkable difference to engine noise for me, was the addition (replacement actually) of the weatherstrip across the lip where the hood latch is located. After applying this strip along with an overall WS replacement binge some years ago, I remember getting in my triple powered z for a drive, pulling away, and thinking "oh oh somethings wrong! The motor sounds wrong and gutless!" Nope, the noise coming back to me through the hood/cowl gap was sealed by that strip!
    That's funny you mentioned that, because that's the only weather strip I didn't install. Now I will install it and see if it makes a difference.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User madkaw's Avatar
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    Quote Originally Posted by Blue View Post
    Most drown it out with ITB's or Webbers/Mikunis/Solex
    Did that and it worked to an extent! I guess if I just keep my foot in it I will be fine!
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User madkaw's Avatar
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    Quote Originally Posted by FastWoman View Post
    Two problems come to mind. First is that there isn't a lot of room between the engine and hood. Second is that the engine compartment gets rather hot even as it is, especially in the pre-'77 unvented hoods. Insulation would make the problem worse.
    I think one of the reasons the sounds resonate is because the hood IS so close to the valve train. The heat is a consideration though. I wouldn' t insulate the whole underside of the hood if I did this, probably just the " hump" area
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

  15. #15
    Supporting Member pbarcher's Avatar
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    I highly recommend Dynamat products, which have greatly improved my 73. In addition to using Dynamat on the firewall, transmission tunnel, floors and doors,etc. I added .25 in. Dynaliner to the trans tunnel and used .5 in. Dynapad on the floors under the carpet.

    After installing the Dynamat on the trans tunnel, it was still hot to the touch, but by adding the Dynaliner (which is stick-on) it was dramatically cooler. I re-installed the original vinyl over both layers and the interior appears completely stock.

    The only place that I didn't insulate was the roof. The vinyl is like new and I was afraid to mess with it.

    Peter


    Peter Barcher
    Original Owner of HLS30-161241 - Mfg. 5/73
    Silver 1973 240Z

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    Registered User darom's Avatar
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    I used a similar product to Dynamat, made by Secondskin (Damplifier):
    http://www.secondskinaudio.com/

    Due to the catalytic converter in my car, I had to double insulate the tunnel portion. It worked and cooled great. I also applied the Damplifier to the roof and doors. Great adhesion properties. They also carry products for the heat/firewall/hood insulation.
    - 1976 280Z
    - 1967 Camaro RS

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