Del Sol, Underbelly Pan
 

1/31/2012 Update on page 4, bellypan version 2.0

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Black Coroplast for stealth
http://i101.photobucket.com/albums/m...r/IMAG0347.jpg

Before:
http://i101.photobucket.com/albums/m...r/IMAG0349.jpg

Work in Progress:
http://i101.photobucket.com/albums/m...r/IMAG0351.jpg

Filling up the gaps:
http://i101.photobucket.com/albums/m...r/IMAG0352.jpg

Driver side complete:
http://i101.photobucket.com/albums/m...r/IMAG0354.jpg

Next: passenger side, rear bumper

Black looks all macho and whatnot, but white reflects heat better. Makes obvious any drips, leaks, or burns/distortions, handy to know about. Also makes it easier to see what you're doing while crawling under the car.

Near heat sources, you might consider application of aluminum foil tape (like duct tape, but stronger, costs about the same at hardware store).

White reflect sunlight better but does white coroplast reflect infrared better than black??

I think black might last longer in UV which isnt an issue below the car. If you wanted a material that last longer and looks better than coroplast buy alumalite. Alot of people make splitters and sometimes undertrays for their expensive sports cars out of that.

Updates: Passenger side, rear bumper
 

Passenger side: unscrew taps holding on the side skirt, this allows you to slide the coroplast in between the side skirt and body.

http://i101.photobucket.com/albums/m...IMAG0356-1.jpg

There is also a small opening for the jack point where you can thread the coroplast up to hold it in place while you are screwing it in.

http://i101.photobucket.com/albums/m...r/IMAG0359.jpg

Closing the gaps on the rear bumper:
http://i101.photobucket.com/albums/m...IMAG0368-1.jpg

Finished Product, Rear bumper:
http://i101.photobucket.com/albums/m...IMAG0366-1.jpg

Mid-car, showing exhaust clearance:
http://i101.photobucket.com/albums/m...IMAG0364-1.jpg

View from the front:
http://i101.photobucket.com/albums/m...IMAG0361-2.jpg

Observations: did a preliminary quick run through my usual test spot, got 54.6mpgs (my previous run with current aero mods minus the belly pan 51mpg).

will do a few more runs to get a more accurate reading. Oh, and the road noise has decreased immensely!

Nice work! Where'd you get the coroplast, what thickness, and what did it set you back?

How did you fix the coroplast to the underside ?

I can see some tie-wraps - won't they tear into the coroplast when it vibrates during driving ?
Do the screws go into the metal , or into other plastic fittings ?

Looks like plain 4mm coroplast to me.

Does 10mm coroplast come in colors other than white or is that just my local sign supply shop??

I got my coroplast from a local plastic's supplier called "Paragon Plastic." You can also google for coroplast or corex distributors to try to find a local distributor. Or you can also call your local sign shop and ask for the info of their suppliers as well. Since it is nearing election season 11/2/2010, some other users on here obtain signs from the local officials who won't use them anymore.

Coroplast is 4mm Thick

White cost's around $17ish per sheet, Black costs $20 per sheet...2 (4'x8') sheets = set me back $40

I screwed the coroplast to the plastic, outside edges of the car such as the front bumper, both side skirts, and the rear bumper. Then for the "inwards" parts, yes i used Zip ties because I didn't want to make this a permanent installation. I've seen another red del sol from "CleanMPG" drill directly into the metal frame. So as far as durability, time will tell.

In terms of ripping, I was concerned about that, that's why I tried to make the hole from the zip tie closer towards the mass of the coroplast as possible (instead of near the edges where they could rip easier).

Yes, coroplast comes in all colors of the rainbow...literally. However, white is the cheapest. I found that my local distributor carries all of the colors, however, most sign shops just carry white.

Yes, white reflects infa-red and ultra-violet as well as light energy in the visible spectra better than black, so would be cooler if you left it in the direct sunlight, etc..

Zip ties seem an excellent idea. If you need local reinforcement of the Coroplast, simply insert a short length of wood dowel of the right thickness into the Coro flutes and tie the Zip around that. (Distributes the load while reinforcing the plastic.)

Otto what is the emissivity of white plastic?

BTW, Jedi, you're doing a fine job of this project. Coupla thoughts:

1. To smooth air over that gap for the exhaust pipe, why not consider aluminum window screen, held tight? Lets heat out, alu. screen is a superb heat conductor, so dissipates hot spots.

2. Control arms move up and down, and make drag hanging in the breeze. Since Coroplast is flexible, would it work to tie panels of it to the control arms, that move up and down with the control arms? Such panels could be fixed at their forward (upwind) positions, and their trailing edges be tied to the control arms. Perhaps elastic ties could be used, to stretch a bit as the control arm/Coro fairing move up and down. This would make almost all of the car's underbelly smooth and flat. Properly done, Coro gaps could act as engine heat vents, drawing hot air out of the engine bay by Bernoulli effect, for less cooling drag.

Dunno, but white is less emissive and less absorptive than black, but much more reflective, so stays cooler in sun. On a sunny day, put your hand on the roofs of various colored cars, and feel that white is coolest. White stays in a narrower temperature range than black, for less thermal stress. That's why German sailplanes are required, by law, to be white--materials last longer with less solar or UV degradation.

Maybe, driving across Death Valley in July in your car with white belly pan, the white would reflect more heat energy back to the road, helping keep your car cooler, getting an extra 1/1,000 mpg since the AC does not need to work quite so hard. That's a stretch, I know. Sorry.

I like white for belly pans because if stuff drips off, say, a radiator hose or oil pan, the drips are easier to see on white. Also, crawling under the car or looking down into the engine bay it is typically too dark to see very well, and white would reflect light better so I can see better. That's just me, though. Overall, probably a chocolate vs. vanilla debate.

When I do my old Ford van belly pan, it will be whatever color politician's sign I can most easily "borrow.":D

Aluminum meshing would be an excellent idea, there is another user on here with a 2002 Infinit Q45 that is doing the same thing.

In terms of the control arm panels, I am picturing something like this in my head?

http://i101.photobucket.com/albums/m...larmpanels.jpg

I was googling "alumalite," yes it says its very strong, light, and durable, however, the nice thing about coroplast is that its very flexible (and strong, light, and durable). Plus the pricing for a 4'x8'x 0.5" (thick) alumalite sheet is $545 :eek: The same size coroplast only costs $20ish.

As another user on this forum said, people always mess around with different build materials on here, but in the end, they all end up using coroplast because its light, flexible, waterproof, durable, and CHEAP.

well alumalite is $88 for 1/4 inch and $126 for 1/2 at my local place, you'r getting ripped off. Alumalite is used for permanent signs. It doesn't break down in the sun and get brittle, it has a smooth enamel finish and is stronger.

I pay $15 for 4mm coroplast which comes in all the colors of the rainbow and $33 for 10mm only in white.

Otto is correct.

A reflective surface, such as shiny aluminum or a mirror for that matter is better at reflecting heat away from the coroplast.

White would be the next color of choice, even for keeping the sun's UV from degrading the material over time.

The worst color is black, which has the most absorption of visible light and/or UV.

Jim.

My budget includes Coroplast, especially right after the next election in November. Those politicians must be good for something. Once I get the free stuff properly sized and installed, may replace it as needed with some nice new white stuff.

Yes, the Coro under the control arm is the idea. If the wind catches it and it rips off, it's so light that it probably would not cause damage to car, tires, or another vehicle.

This may be a stretch, given the difficulty of gluing anything to Coroplast, but has anybody tried using adhesive-backed Velcro on Coroplast?

Good idea !
A thin metal rod (or even thick wire) would easily fit into the thinnest coroplast.

Okay but is coroplast of any visible color reflective to infrared heat? there isn't that much sunlight or uv below the vehicle to worry about.

Why not use overlapping panels, with the front panel being fixed at the front, and flexibly mounted below the control arms and at the rear by inverted T-shaped supports running through lengthwise slits in the coroplast ?

That's basically what I had in mind, overlapping panels that move up and down with the control arm. Think: Big fish scales or bird feathers, overlapping like roof shingles. Thin coro. oughta flex pretty good.

T-shaped supports might not be needed if you slip some skinny wood dowel rods of correct size into the coro. flutes, where needed.

On the coro, if too close to a hot spot from exhaust, etc. put some aluminum foil tape on, which both reflects heat and dissipates it, alu. being an excellent heat conductor. ~$3/roll at hardware store

UV not a problem whatever, under the car. Coro. is, after all, designed for outdoor realtor and political signs.

Again, the reason I like white is cuz you can easily see and trace leaks or seeps. Instead of just some dark wet spot in the dim recesses of the engine bay, you can see green coolant stain, red brake fluid, brown oil, etc.. Wipe off with sponge, so next time you look you know if it's a new stain or not. Also helps when you drop some washer or nut Lord knows where down there.

Guess what i found in my back warehouse? Foil tape! Why the hell do we have this?

Dowels in the coro flutes is a great idea, i wouldve never thought of it.

Damn i thought i was finished with the under/car work.

Nice neat foil tape on edges of Coro would look real purdy, and keep tiny little spiders from hiding in the flutes, too. I plan to use the stuff to edge a NACA duct made with a carpet knife, to cool the oil pan on my old Porsche.

Updates
 

The piece on the left, i guess, has been catching the wind and snapped the zip tie. Which explains the annoying scraping noise for the past week :mad:
http://i101.photobucket.com/albums/m...IMAG0380-1.jpg

Stopped by home depot and bought a piece of aluminum sheet metal. Attached it to the front piece so now the air should flow smoothly in that section. And since its aluminum, heat from the exhaust pipe shouldn't be a problem.
http://i101.photobucket.com/albums/m...IMAG0382-1.jpg
http://i101.photobucket.com/albums/m...IMAG0385-1.jpg

Now Im tempted to cover the entire exhaust with aluminum sheet metal :)

Also lined the edges near the exhaust with foil tape.
http://i101.photobucket.com/albums/m...IMAG0384-1.jpg

I realize the last post on this thread was like a year ago, but I was wondering if there was follow-up info on how the aluminum sheets held up covering the exhaust pipe. I'm considering doing a belly pan on my Del Slow using aluminum flashing. And I'm a bit concerned about covering over the pipes and how that might effect the car And pipes in the long run.
Was there an increase in internal heat? Did or would the heat of the pipes be conducted across all the metal keeping things cooler? Should space be left around the cat. converter? Any feedback is appreciated.

Thanks,
Punch

I LIKE THE BLACK so there

I'm actually only using one sheet of aluminum to cover that ONE section of exhaust piping to connect the front and rear section of corplast, and it is holding up very well in terms of heat. Otherwise, I have about 3-4 inches of clearance between the coroplast and exhaust pipes and have not had any issues of heat melting the corplast either.

Aluminum is an excellent conductor of heat, but one of the concerns people have with underbelly trays if you were to have an exhaust leak, there is no where for the exhaust fumes to go but into the passenger cabin area. I didn't want to take that risk, therefore I left the bulk of the exhaust pipes uncovered and only lined front, sides, and rear of under the car with coroplast.

Thanks for giving me a more complete picture of how far you went with your belly pan. I'm still working on getting my Del Sol's engine and mechanics back into as good a shape as I can and then I'll begin working on the underbelly.

I know this is kinda off topic but your grill block was done out of Coroplast as well right? How did you attach it?

Version 1.0 was attached using clear packing tape.
http://i101.photobucket.com/albums/m...r/72797bf0.jpg

Version 2.0 was attached using L-brackets from home depot and some bolts and nuts.

Version 3.0 (current), is a made out of of coroplast/fiberglass and shaped to fit the grille opening a lot better. Then used bondo to fill up the gaps and clean up the edges. It's still attached using L-Brackets/bolts/nuts.

http://i101.photobucket.com/albums/m...r/3d55b160.jpg
http://i101.photobucket.com/albums/m...r/IMAG0283.jpg

I didn't put enough layers of fiberglass so it is warping on its own, but its been too cold this winter to continue working on it. Hopefully i'll get around to fixing it in the spring time.

As far as mounting points for the L-Brackets, i screwed them into that horizontal bar that runs along the middle of the grille opening.

What size tires you have, they look like they fill the wheel well nicely.

They are 205/50 R15... a bit fat in terms of ecomodding, but they are left over from my days of souping up my car. Once the tread wears out, i'll most likely switch to a Low Rolling Resistance tire.

version 2.0
 

the belly pan as it is was not very sturdy. it's always got caught in the wind and the choroplasr melted near the transmission and engine. therefore I decided to build a frame out of aluminum to make it more stable.

the frame is made out of aluminum screen door frame found at home depot. it is sturdy because of the box shape, lightweight, and cheap.

5/16 in. x 3/4 in. x 84 in. Aluminum Screen Frame-3021650 at The Home Depot

the main goal was to use pre existing holes and not drill into the body.

First, I made 4 horizontal braces. I used pop toggles from home depot to drill into the pre existing holes that are originally for the side skirts

http://i101.photobucket.com/albums/m...e/IMAG0033.jpg

Front of the car brace. It's attached to existing tow hooks

http://i101.photobucket.com/albums/m...e/IMAG0008.jpg http://i101.photobucket.com/albums/m...e/IMAG0006.jpg http://i101.photobucket.com/albums/m...e/IMAG0009.jpg http://i101.photobucket.com/albums/m...e/IMAG0010.jpg

From the back http://i101.photobucket.com/albums/m...e/IMAG0011.jpg

Next is 2 parallel bars down the back. I plan on covering the exhaust with aluminum sheets http://i101.photobucket.com/albums/m...e/IMAG0022.jpg http://i101.photobucket.com/albums/m...e/IMAG0023.jpg

NEXT step is to attach the middle bars to the rear horizontal bar http://i101.photobucket.com/albums/m...e/IMAG0029.jpg

Then, tomorrow, attaching all of the choroplast back on.

I gave it a few tugs, and its actually very sturdy!

What do you plan on doing about the melting issue?

I'm.going to cut out the melted.sections and replace.with aluminum sheets