looking for a cheap/light/easily worked material to make an airbox and a couple of other aero devices on my 86 Camaro.. i've seen Coroplast mentioned on a few different forums as one potential material.. i know they make signs out of the stuff that seem indestructible, but how would it hold up in the shape of an airtight box filling the gap between the nose and radiator of a car? how about using it in the engine bay to make a ram air box to the air cleaner? partial belly pan?
MotoIQ sure likes the stuff. Here's Dave Coleman's take as well as some construction tips:
http://www.motoiq.com/magazine_articles/id/1721/wrench-tips-17--election-day-ductwork.aspx
And according to the manufacturer, the melting point is 324 degF:
http://www.coroplast.com/technicalinfo/resinspecs.htm
The thing about Coroplast to be aware of is that it wants to bend along the length of the flutes. Unsupported spans of it will bow, flex, or sag.
For a ram air box, I imagine you would have a tough time sealing it up.
It wont last long.
I made an engine back belly pan and some air management pieces out of it for a 96 civic hatch that are three or four years old and it has all held up very very well. It bends easily and sharply along the corrugation and can be convinced otherwise but has quite a bit of memory. It fastens with rivets/screws and load distributing biggish washers very well. Not sure about an air box as it is has such inconsistent characteristics, but belly pan and 95% sealing quick fabrication type of air management for sure.
The belly pan made a noticeable difference in the areo slipperiness of the car. I was surprised that I could feel it and measure a gas mileage improvement.
ecomodder.com and gassavers.org both have some wild coroplast projects posted.
Interesting... I've never heard of this stuff so I'm tagging this for future reference.
I have used it before also, works great and the only time it has every melted is when it was exposed to direct exhaust (forgot the hole for the exhaust cutout) and even then it was only a little melted.
For an air tight airbox I would use it with some angle/square aluminum from homedepot. Fasten it to the aluminum along the edges with rivets and washers. You can seal it better with sealant or tape.
Oh and you can double it up for high impact/high flex stuff
As a long time sign guy and holder of a BS in Polymer chemistry, I wouldn't put it in my engine bay. Or anywhere it's exposed to long term solar exposure. Heatcycles and UV make it brittle.
I used it to make some under trays. I laminated 2 pieces together crossing the 'flutes' to strengthen it like plywood. I used some liquid nails I had laying around and set some weights on it while it set up. It did melt on me where it was against the oil pan, not a complete met through or stuck to the motor, but the panel sagged and some of the flutes collapsed. I just held it up with zip ties.
thanks for the responses.. once the car is actually running and moving on it's own, i'm gonna track some down and get to fabricatin'.
In reply to former520:
Wow it melted on against the oil pan? How hot does your oil get? I have heard you are looking at engine damage (bearings) with temps over 240*
In reply to novaderrik:
I think I said it in the motoiq replies in addition to the vote for me signs, gas stations are a good free source for the stuff. They tend to change the signs out monthly and just toss the old ones. Ask a few stations to hold it or call you when they are throwing it out.
jere wrote: In reply to former520: Wow it melted on against the oil pan? How hot does your oil get? I have heard you are looking at engine damage (bearings) with temps over 240*
you don't need to reach the melting point to cause something to weaken- you can bend 1/4" thick steel with a propane torch, but you won't melt it.. also, temperature isn't always a reliable method to tell how much heat energy is focused on a point.
novaderrik wrote:jere wrote: In reply to former520: Wow it melted on against the oil pan? How hot does your oil get? I have heard you are looking at engine damage (bearings) with temps over 240*you don't need to reach the melting point to cause something to weaken- you can bend 1/4" thick steel with a propane torch, but you won't melt it.. also, temperature isn't always a reliable method to tell how much heat energy is focused on a point.
It wasn't melted as in dripping on the ground. The top layer was warped and sagging between the verticals, some of the verticals were sagging as well. The oil pan in question is a 92 BMW M50 finned aluminum pan. Never had any heat issue, but the entire cooling system has been replaced and made it through Phoenix's summer.
just FYI, most sign shops are paying less than $10 for a 4'x8'x4mm thick white sheet of this stuff. If they're buying in decent bulk it's less than $8. If you need bigger pieces and don't want ads on them, most shops will sell you blank sheets for $15-$20 and be happy to do it. If the first shop won't, just find another.
The stuff is also available in colors, and in a 10mm thick version that is in-freakin-destructable, but pricey.
Another material that is less well known is Sintra - this is a solid core, smooth material that is made of a micro-foamed PVC plastic. It warps in sun or heat, but it is fantastic for interior use (guage clusters, etc.) It can be heat formed, brake bent, and welded with common PVC pipe cement. With some thought, its amazing what you can make. And it's available in 3mm, 6mm, 13mm, and 3/4 and 1" depending on brand abd color. And it can be had in black, white, and myriad colors.
bringing this thread back up with an update..
i got a 4X8 sheet of 5mm white coroplast 2 weeks ago for $25.. the guy at the sign shop said he sells a lot of it to a local RC airplane club and they use it to build the air frames, but i was the first guy to ever buy it for aerodynamic devices on a car..
made and air box to seal the radiator and carb air intake to the front grill, and a filler piece between the nose and the radiator support. the stuff is amazingly easy to work with, amazingly strong, and stays in place with nothing but a few self tapping screws jammed thru it..
i had about 3/4 of the sheet left over after that, and the other day i got the bright idea to make some door panels for my Camaro out of it since i didn't have any door panels in the car and i'm gonna be driving it to Texas in a couple of weeks.. so i hit up the clearance rack in the fabric section of Wal Mart and got 3 yards of cool checkerboard pattern black fabric and 3 yards of fleece blanket material (with a pic of a 2 foot tall kitten on it every 3 feet) to use as a backing.. it took me about 20 minutes per side to cut the coroplast to shape, then about another hour total to glue the fleeces and fabric to it and screw it to the doors with self tapping screws.. they look really nice for something i just threw together in 2 hours out of $25 worth of materials, and i think they will be at least as durable as the oem door panels and weigh half as much.. i didn't take any progress pics (d'oh!!), but i'll try to get some pics of the finished door panels up tomorrow.. if i had a little bit more coroplast left over, i'd make some panels to put on the inside of the T tops to finish off the interior a little bit, but sadly i only have enough left to do one.. i've also got over 2 yards of the black checkerboard material left over- probably enough to do the headliner and every cloth surface in the car- but my nieces just had to have the extra 2 yards of "kitten fleece" to use as blankets...
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