Hood Insulator

[radioranger]

I've worked on yachts that used a lead foam combination , check out jamestown distributors up in rhode island they use it for noise and heat insulation, the ultimate as far as noise goes also . pricey but nice stuff.

[YeahPete]

I'm going to attempt to hit the junkyard this weekend. Thank you all for your comments. I am looking for cheap of course.

[ajjct]

rock wool is used to grow plants mostly. and yes it holds water, it is NOT WATER proof unless it been treated. at the price its not worth it. in my opinun

[ctgottapee]

Originally Posted by WesternStarSCR

I just saw a How It's Made episode on Roxul brand of insulation, made from 'rock wool'. It can handle high heat and is water proof as well. Anyone try that, as it seems if it strategically secured under the hood, it has great heat retaining and sound deadening properties. I have no clue on cost or availability but they melt slag, coke and salt rock to melt it and spin it into fibers.

Roxul is similar in insulating value to fiberglass bats or loose cellulose.

It isn't water proof, but it doesn't absorb water, ie you can get it wet but it will naturally dry.

It is not as widely available in the US as the 'pink panther' and his fiber glass bats has the markets cornered. It doesn't traditionally come cut in sizes that would go under the hood easily, normally for a stud bay so it would be too thick and you'd have to find a way to keep a bunch of rolls together, but it does cut so its possible.
It's cost is usually higher but in the same ballpark. Being a waste product, its all about market and volume really. It's mostly use in commercial building where fire codes make it more valuable.

It doesn't insulate or sound absorb any better than other things, and some items like foam insulate much better.

[ctgottapee]

Originally Posted by Frank Lee

I disagree. Clearly the space is insulatable. And I want it to not get much hotter when it's moving, the desired function being to retain heat longer when parked.

I was just attempting to work through the logic.

The amount of space under the hood does not leave enough room for any realistic Rvalue, and most traditional engine compartments have too many other routes of heat loss for it to make a difference (by design).
While not costly, it will be as effective as doing nothing.

Even exotic materials that could make a difference wouldn't matter. Almost every item in the engine bay is made to dissipate heat quickly.


And as I noted (while not directed at you) if you use foil lined insulating under the hood, you will actually be losing the heat that comes down through the hood from the sun during the day, and its quoted Rvalue does not apply to heat coming out of the engine bay. The foil doesn't reflect heat back as many think.

[Frank Lee]

Since even cardboard makes a noticeable difference, I don't think r-value has as much to do with it as merely slowing down the drafts.

Maybe you should just try it.

[NoD~]

^^^agreed. I noticed 5-10* increase over a 1-2 hour period with my little bubblefoil/cardboard contraption. Plus, I could drive for hours, stop and feel the hood after 5 minutes and it didn't feel warm. It's doing some insulating, one way or another. Of course, completely sealing the engine bay would be the right start, but this was cheap and easy.

[brucepick]

I often see people wearing coats with their heads and sometimes their hands uncovered. They seem to benefit from the cost even though they are not completely sealed off from the environment. Yes, a wraparound type hat plus gloves would give more protection.

[ctgottapee]

Originally Posted by NoD~

^^^agreed. I noticed 5-10* increase over a 1-2 hour period with my little bubblefoil/cardboard contraption. Plus, I could drive for hours, stop and feel the hood after 5 minutes and it didn't feel warm. It's doing some insulating, one way or another. Of course, completely sealing the engine bay would be the right start, but this was cheap and easy.

The issue is, and the reality is, that the insulating effect is darn near not scientifically measurable to any meaningful value.
The bubble foil has nearly zero insulating value on the underside of the hood when trying to keep heat in, and that is when you don't include all the other avenues of heat loss.

If you were to do accurate A-B-A testing you would see no difference.

There are other methods that do work, but they have limitations to:
-like The coolant heat retention method used by the prius; surely they would just line the hood for a $1 in bubble wrap if it actually worked.
-or frost heater type fittings plugged in to electrical source.


The engine is designed to shed heat fast; you can't alter that with a little cardboard.

[Frank Lee]

Yes you can.