Does anyone know of some sort of foam (rubberized ? ) suitable for underhood use?
I need to come up with something to seal my “airbox” up with the underside of the hood. At the widest, I have a 3.5" gap to seal.
The best I can come up with is upholstery foam since it’s flame retardant, and easy to cut as needed. Not sure how it’ll hold up to the heat, etc…
pipe insulation
Thought about that too, but it’s just not thick enough unless I were to layer it.
maybe extend the box up some how to make the gap less. like put a lip around it then the rubber on that
Maybe pics will help… I’m pretty lousy at fabricating. As much as the box was, I hate rivet anything on to it.
Where you see the bottom of the hood, the sides seal up, it’s the raised portion in the center that presents the problem.
If I could find a block of foam that I could cut to shape and glue to the underside of the hood it might work.
what have other owners of that same intake setup done? I’m sure you can find examples online somewhere. Ther just might be an easy solution you haven’t though of yet
That intake seals up just right to a stock hood with the rubber clip on rubber stripping it comes with.
Found only one person with the same setup as mine, and his isn’t sealed up either.
I don’t mind gluing foam under the hood, I just don’t want to find out the hard way that it won’t withstand underhood temps. 
Instead of foam, why not attach a “rubber flap” to the hood, that is positioned such that it will land directly in front or behind the RAISS box. That should create enough of a seal to keep the cold air aspect of the intake working.
The thought crossed my mind, but attaching it to the back of the raiss.
I could glue it so it’s removable.
Couldn’t find a suitable rubber either though. 
I think if you used Door Edge Guards (the stuff you buy at pep boys that protects the edges of your door)
that would work fine. Plus its only like 5 bucks for 5 ft of it. We used this on whiteys 240 when making a hole bigger for the intercooler piping. Just to give it that smooth look.
But the gap that needs to be filled is about 2 foot wide by 3" or so tall. 
I’d get some better pics, but the box is up at AMF getting finished right now…
I was thinking about one of those big mud flaps used on 18 wheelers. As long as you stay away from the exhaust, all should be well.