Does anyone have specifications on the temperature ranges/tolerances of coroplast? Have looked online, with no luck. I would like to explore the possibility of making a grill block and or underbelly for my 91 cutlass supreme more aerodynamic.

If not coroplast, what is a good quality but inexpensive material?

25-27 mpg is pretty good, more would be better.

Antares

My Jeep Cherokee ran about 1 week with a belly pan of coroplast (front bumper -> front axle) I was quite a distance from the exhaust, however the engine bay temps on a Jeep Cherokee can be quite extreme. When I pulled off the coroplast after 1 week, it was covered with oil/dirt, but had not melted/deformed in any way.

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I can see the one advantage being lack of rust on the underside of the body for sure. How much of a gas mileage difference did you notice when you most of the underbelly covered?

Antares

It's propylene, so you could look for info on propylene melting points or glass transition points.

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General Specifications of Polypropylene co-polymer resin

Normal temperature performance range: -17 degrees F to 160 degrees F
Melting point: 324 degrees F

Only if you make sure that all the openings on the stuff are sealed.
I just slapped the stuff on my car, and anytime it rains,water gets trapped between the underbelly caver and the chassis.

Antares2k6: My belly pan was pretty rudimentary. You can see my MPG results in my garage. Don't let those numbers discourage you, as I have no SG, superMID, or any other way to measure fuel economy aside from going fill-to-fill. I slapped it up there mainly to see if I would have a problem with heat, noise, or suspension rubbing. (was OK on all but tire rub, but I just need to trim it up a little more)

I'm going to finish tweaking my grille block first, then I've got an e-fan to install. I'm looking at re-designing/re-installing my belly pan here in roughly a month or two.

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I have recently conducted melting point experiments involving coroplast and the rear-most muffler of a Honda Element. When in contact with the muffler, the coroplast melts. That's about all I'm gonna say about that.

On the positive front, when tucked under the heat shield for the catalytic converter, it doesn't melt. Not yet anyway. :-)

Oh, I should probably conduct some flammability tests as well. I mean real ones, not just putting stuff under my car and hoping it doesn't catch on fire.

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I did some combustion experiments on polypropylene when it first came out in the late '60's. It burns. But definitely test it yourself. Stick some into a fire or try light the edge of a sheet with a match.

I was taking an 8th grade physics class. Whoever made the stuff provided a bunch to our instructor who had us "experiment" with it. A pencil shaped stick burns. Drips too, a lot like candle wax.

The flexibility allowed hinges if it's molded with a thin segment joining two thicker flat ones. Neat stuff and far superior in many ways to the other plastics in use at the time.

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Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.

Now driving '97 Civic HX; tires ~ 50 psi. '89 Volvo 240 = semi-retired.
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I ran an "experiment". Coroplast burns quite convincingly, and drips hot burning liquid. Something to keep in mind.

I have safely secured the coroplast away from my exhaust system.

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