udidwht,
I think I'm going to have to side with the folks that think this might create a worse problem due to excessive heat. As wolfe10 mentioned, take a piece of that material (I'd think 1' x 1' would be enough) and while someone else is driving, you hold onto it with both hands and stick it out the window at highway speed. The air rushing toward that material will see that material almost like a wall, a higher pressure area will be created in front of it, and incoming air will be deflected around the material by that higher pressure. The same will happen in front of your radiator and you'll be limiting the amount of fresh, cooler air, getting to your engine. Vehicle manufacturers usually spend a lot of time making sure that proper air flow exists under a wide variety of environments. Remember that fluid flow is from high pressure to low pressure. A high pressure area in front of that material will cause the air flow to find a lower pressure route.
As others have said, carefully monitor your temps. Even if things are just running moderately hotter, higher operating temps tend to shorten the life of lubricating fluids, transmission fluid especially, so you might wish to shorten those change intervals.
The material you purchased is used in an application where there is a low pressure area created behind the filter by the circulation fan in the A/C. It is also (usually) contained in a rigid frame so air must flow through it, and it is not exposed to the elements (moisture especially). The air is drawn in THROUGH the filter. The air filter in your engine operates the same way, the low pressure inside the intake manifold (due to the intake strokes of the pistons) draws air through the air filter with atmospheric pressure on the outside creating the pressure differential.
One other thing I thought about...you said you held it in place with zip ties. LOL...I'm a "zip tie guy" myself. But that foam material isn't that strong. If the material rips free, can it get "sucked in" to the radiator or go underneath and get wrapped around the fans and belts? Just a thought. I could be way off base with that, but figured I'd mention it.
Oh...just had another thought...what about in the rain? That material will get heavier and stress those zip tie connections even more, while further limiting air flow.
Personally, I'd think you'd be better off with hardware cloth (actually wire mesh). I think the size they recommend for "rock catchers" is 1/2" x 1/2" holes. It might not catch everything you want it to, but it should help and will pass a lot more air. Until/if it becomes clogged.
Hey...it's your rig. Maybe it'll work and won't cause you any problems. We'll keep our fingers crossed for ya'!
๐Good Luck,
~Rick
2005 Georgie Boy Cruise Master 3625 DS on a Workhorse W-22
Rick, Gail, 1 girl (27-Angel since 2008), 1 girl (22), 2 boys (23 & 20).
2001 Honda Odyssey, Demco Aluminator tow bar & tow plate, SMI Silent Partner brake controller.
