Styrofoam insulation for inside cowling

[john from md]

I am about to try a winter project to quiet down my 85HP engine. My plan is to glue R9 insulation foam on the inside of my cowling. I plan to use either 3M77 or Liquid Nails for Styrofoam. Both of these are good holders.

My only concern is the amount of vacuum under the cowl. If I glue the foam on properly (covering every square inch) will it withstand the vacuum under the cowl?

Anyone have any thoughts on the matter?

Regards,

John

 

[Frank Acampora]

Re: Styrofoam insulation for inside cowling

Since the air vents under the bottom carb are larger than the area of the carbs themselves, and since there is also another air vent on the top rear of the cowl, there should be very little to no vacuum under the cover provided you do not cover the upper air inlet.

However, think twice about the type of foam you want to use. Some are intolerant to gasoline. No matter how clean your engine is, there is always a bit of gas in the front, and some vapors around too. Even if the foam has an aluminum cover sheet, eventually the covering will get cuts in it and deterioration will start.

I found some industrial bubble packing with 1/4 inch bubbles, used for frozen food insulation, and aluminized on one side. I intend to try that. Even if a couple of bubbles get popped during the course of removing and reinstalling the cover, they will only be a small percentage of the total and no deterioration will occur. On my old Chrysler 55, I used the old woven jute carpet padding and it worked fine for 30 years. I don't know if this type is still available though and it made the cover heavy as hell.

 

[MWBROWN]

Re: Styrofoam insulation for inside cowling

I used a black closed cell foam 1/2 thick from McMaster Carr. They sell to anyone.
I also used rubber cement, as I knew it would not react with the fiberglass hood or the foam. It has been on for 3 years now, with no ill effects. Did not add too much weight to the hood. If I find the exact order number, I will post.

Make sure you leave clearance for the flywheel. It is the tallest part, and make quite a mess when it chews up the foam. DO NOT ask how I know this.
LOL.

Like Frank said, there is plenty of air flow, just don't block the rear inlet. I had to taper mine to keep from leaving a big gap.

I also found a guy, that I left a post about, the will make a kit for your engine during the winter months.

Good Luck

 

[john from md]

Re: Styrofoam insulation for inside cowling

Thanks for the reply Frank, it made me take a step backwards. I spent alot of time looking up the proper glue that would not eat styrofoam but I forgot about the gas and oil in the engine area!!!

Ok, time to start looking at some other materials. They used to sell a spun fiberglass with foil backing for insulating houses. I wonder if that is still around?

John

 

[john from md]

Re: Styrofoam insulation for inside cowling

MW,

How well did the closed cell foam work? I can get that stuff easily.

I already considered the flywheel. I did not want to be cleaning insulation out of my engine for a week!!

John

 

[johnnythunder]

Re: Styrofoam insulation for inside cowling

How about Carpet padding or even better automotve firewall insulation from an autoparts store

 

[chitownborn]

Re: Styrofoam insulation for inside cowling

I used carpet padding, and it works great, I glued it in with a strong spray glue adhesive then duct taped over the padding now I can barely hear the old force running [lol] it sure does make it alot quieter. I can now hear the stereo when cruising without the thing blasting away

 

[NYBo]

Re: Styrofoam insulation for inside cowling

Based on the types of materials being used, am I safe in assuming that heat isn't a big problem?

 

[john from md]

Re: Styrofoam insulation for inside cowling

Chitown,

What kind of carpet padding did you use? The only stuff I have seen lately is made of a green rubber compound.

Regards,

John

 

[chitownborn]

Re: Styrofoam insulation for inside cowling

Hey John, the stuff i used was not the rubber type padding, its more like a 1/4 thick, like a burlap material that goes under carpet. They were changing the carpet and pad at the casino i work at and I grabbed a piece of the pad that was being tossed out. Im sure lowes or home depot would sell this type of pad. Mine works great so far, its been two years and no signs of flaking or falling apart, you know stuff that could get into those precious force carbs. good luck Don

 

[john from md]

Re: Styrofoam insulation for inside cowling

Thanks Don, I'll try looking for it at some carpet shops around here.

John

 

[johnnythunder]

Re: Styrofoam insulation for inside cowling

There is also a felt type padding about 3/8 or 1/2 thick

 

[RRitt]

Re: Styrofoam insulation for inside cowling

i got 1/2" neoprene closed cell foam with aluminum skin off ebay and used high grade contact cement to glue in place. I got it for $35 and there was enough to do both engines. Being a closed cell material means that spills and splashes never soak in and that clean up is just a simple wipe with soapy rag. Being neoprene foam it did a phenomenal job of reducing engine noise. I can't imagine anything working better or lasting longer.

 

[noah4009]

Re: Styrofoam insulation for inside cowling

Hi RRitt, Can you tell me where on ebay or where I can get this neoprene and what type of glue you used? Would like to try.

 

[RRitt]

Re: Styrofoam insulation for inside cowling

a similar item is on ebay currently as item # 290289645485. You can search for that number and ebay will take you directly to it. If it has expired then search for (sound,insulation,sheet) (foam,rubber,neoprene)
that will find anything containing at least one word from both sets.