thinking about an underbody fairing

[lunarhighway]

last week i came across some coreoplast signs at work they where throwing out. these where swiftly transfered from the garbage to my trunk (wich sometimes isn't much difference)

initially i just wanted to make a grillblock, but i've got enough of the stuff to cover the lower end of the bumper as wel. i'd like to span the gap between the edge of the bumper and gently slope down to direct the air over the engine rather that straight onto it.

i know some people here have made similar setups so anyone willing to give some advice in welcome to do so.

what king of FE increase could i expect. i don't do a lot of highway driving but a great part of my dayly commute is between 70 and 90 km/h, a speed range where aero starts comming into play.

i just need to find a simple way to make a rigid frame to attach things to. there's nothing to attach the trailing edge of the cover to so i'll have to find something to span the length of the bumper to the rear. i was thinking in the direction of a thin wooden girder (whats a more appropriate word?) i think wood whould be lighter, stronger and cheaper than a metal tube exept aluminum maybe, of equal dimentions.... but i'll see what comes up.

hopefully i can find time soon to make this so i can start harvesting these FE gains

[Danronian]

I just installed an experimental grill block on my car (aka cardboard), and already I have noticed that the car gets up to normal temp faster. And since the sooner the engine gets off of high-idle, and the o2 sensor is heated up working, the better gas mileage I will see.

I need to find some free chloroplast material so my grill block doesnt reshape itself every time it rains..

[ajohnmeyer]

to solve the self-deforming grill block prototyping problem I went out and got a roll of colored duct tape, and used it to cover the whole piece of cardboard with it. Plus, the color of the tape roughly matches the color of my paint.
It rains nearly every day where I live, and so far this is holding up quite well

[basjoos]

I bent and attached 1"x 1/4" aluminum bar stock to create the nose shape I wanted and attached the coroplast to the aluminum. I drilled and tapped screw holes to attach the bar to the car's bumper and the coroplast to the bar stock.

[lunarhighway]

i've used taped card in the past, and i works really well, as long you you make sure the edges are well sealed. you can also use tape directly depending on the size and shape of the holes you need to cover.

basjoos.

i've always liked your dedication to aeromods... seems like you've build a new car, but sutch a fairing would get me pulled over and forced to remove it in no time.

on the other hand i did recover some old drawings i made for a fairing that blends my licence plate with my bumper... the sides are fairly smooth, but in the center there's a recess with the lince place mounted above. gains from this might be limited but it should make the front of the car a littel smoother.

i'm planning to focus on an underbody fairing mostely, and on the grillblock... these should deliver some improvement over the stock situation i hope.

[brucepick]

I've used wood for various mods with good success.
Sometimes as framing, sometimes as the surface material.
There's plenty airflow in most locations so even if it gets wet, it dries out again.

My most recent project used plywood. I primed it with oil base house paint primer because I don't want the plywood delaminating.

Duct tape will leave behind a nasty mess when you finally take it off. Can be cleaned up with WD-40 or Goo-Gone but either way it's a PITA. Outside of that, it works really well.

[lunarhighway]

for tape i've used vinyl electrical insulation tape. it's sticks very well to smooth surfaces, and proved to be weather proof. unfortunately it's fairly expensive. when removed it doesn't leave behind any big mess so that's an advantage.

plus it can be had in a various colors to math the finish of the car