xj220sc

You should buy this at lowes and a few cans of black spray paint

This is bathroom wall liner I'm pretty sure its plastic.

Its pretty strong, light, and $34 for a HUGE sheet. I was going to buy it but it couldn't fit in my car!

Braineack

iTrader: (62)

I wish I could find another supplier of the ABS material I used for my shrouding.

bbundy

FRP = Fiber Reinforced Plastic.

probably glass fibers in it but I don't have a clue what the plastic content is.

Bob

spaztikcamel

quick thread jack

how noticeable is a flat underbody when compared with stock?

does it feel worth the effort or is it more of a thing you would do for a serious track car?

hnguyen037

there is no doubt a flat underbody would be beneficial on a street car, however you probably wouldn't notice it at all unless it were on a track car. Also, I doubt anyone that serious would be doing just a flat underbody alone. We're talking about adding splitters, diffusers, and wings, which could mask the effects of just one of the pieces of aero

jpreston

iTrader: (4)

Are those sheet metal screws, just waiting to come loose and ruin someone's $300 hoosier? Hope I'm never at the track with you.

xj220sc

I made a panel using that stuff I posted before and the car feels smoother at high highway speeds. It might just be the effect. That stuff is cheap and easy to cut.

1993ka24det

If you do alot of driving it will with the gas mileage. One of the Magazines did a undertray on an NSX and they complimented on how quite it was on the highway.

hustler

iTrader: (6)

http://pitstopusa.com/c-132804-body-...d-plastic.html

jacob300zx

The aluminum undertray will help with drag and help intensify the effects of the diffuser. Dont forget that once you make it smooth you want to keep that air under the car and channeled to the diffuser so you'll need side panels to keep it under.

greeenteeee

More noticeable at higher speeds, my car feels much more stable at highway speeds.
^+1s....+10 RE: what jacob300zx said about the diffuser. I have plenty more I can do especially with the positive results so far with the minimal work I've done.

I did light under paneling with corrugated plastic. Of the two 24x36" sheets I got initially, most of it went to underpaneling instead of rad ducting (the original intention)

ClubRicer.net.. I mean ClubRoadster.net is not giving me any usable feedback. Probably because these aren't "nice" pieces.

Simply ziptied on, seems to be holding up so far, only daily driving so far.. Few pics. This project started from a blown radiator.

Front, covering only the front sub.





Rear, 24" x 36" piece

It starts a few inches ahead of where the floor ends, in line with the plastic bolts the tie down the plastic fuel filter cover. This pic has another piece intentionally sitting on the mid-pipe to see if it'd catch fire or merely just melt as I anticipated.



Minimal gap between exh pipe and corrugated plastic:



No signs of melting aside from the aforementioned piece, which was to be expected.

Top piece goes under front sub.. I cut out an outline for the front jack point and a rectangle slit for oil changes. Oil temps are within normal operating range. Oil pan surface temps were not recorded pre- or post-... I don't think it's an issue.

Bottom piece is pre- and post- radiator, guiding the air upwards to an eventual vented hood.



24" wide x 36" long, meets the floor and 5" past the rear eccentric bolts/subframe to mate along with the Lexan diffuser (also a prototype).







Never bothered to record differential casing temperatures before adding these. I believe there is still enough airflow in the tunnel for it to cool the diff. After a 30 minute drive, diff casing is at 170 degree temps using an infrared thermo. Just in case exhaust piping was affecting readings, I took a reading of the subframe (110 degree) and the exhaust pipe ("Hi")-- probably somewhere 200+

This is what I have on the front end:


It is at 75-80mm ground clearance, undertray surface is 115mm above ground. Yes, this creates a low pressure region right behind the front-most airdam, and it would be better if it were lower or at least inline with the front subframe, but for clearance issues, I am testing to see how low it can go without scraping it too much. The front-most airdam is more easily disposable than another splitter/undertray.

I've also been doing some non-traditional coast down tests with variations and also between 3.5" pinch vs 3.75"/4.00" pinch heights.

Would appreciate some criticism-- already observing positive subjective and objective results and already have plans for more aero work...

Some sketches/measurements for some brainstorming.





(p.s. sorry for the long post, and this was the most recent thread on this topic)

fastivab6tg25mr

these guys do alot of areo mods and there are tons f write ups on under body trays:
http://ecomodder.com/forum/

Seefo

iTrader: (5)

I am working on something similar:



I finishing up some ducting in the engine bay and the radiator before i continue down the car.

I am using 4mm coroplast (corrugated plastic).

Faeflora

iTrader: (2)

Wow. Corrugated plastic for the cheap win.

Seefo

iTrader: (5)

yea, I bought 10 sheets of 24x48 (4mm thickness) for $70 shipped. 4mm seems pretty good, Its thin enouugh for things that don't need to be particularly rigid, but can be doubled or even tripled up for a splitter. Since its vertically stiff, sealing up the rows with some foam or something for the sort, could make for nice material to do a diffuser also. Either way, depending on the way you orient it, you can go from something that is stiff, to something that is bendable and durable!

Faeflora

iTrader: (2)

I have a boner.


I am not the fabrication lord so stuf like this that is cheap and easy to work with is my type of material. ---- yeah.

Link please!

Seefo

iTrader: (5)

http://www.corrugatedplastics.net/4m...ticSheets.html

Easy to work with is an understatement, I made the undertray in less than an hour. a dremel with a plastic cutting wheel will make you into an arteest in no time!

Oscar

iTrader: (2)

I need to find some of this stuff, I like cheap and easy to build stuff.

spaztikcamel

How do people secure the undertray to their car?

I'm half way through building mine and my plan was to epoxy bolts underneath the car fit the tray into place, use nylock nuts then cut the bolts down to length for minimal cost and ease of removal.

But then I realised that id possibly have to tie these nuts with wire to go on the track. so I decided to look into other ways.

If anyone has a good cheap solution (not cable ties...) please share.

Seefo

iTrader: (5)

I epoxied the bolt on the coroplast. The undertray is in the bumper, so just put the bolts down. The good thing here, is if it comes loose I am not leaving bolts on the track. A nut is a lot less likely to damage a tire than a bolt. And also, its less likely for the undertray to fall off since the bolt is still going through the bumper hole.

Not sure why you have to tie the nut with wire? Stock miata has plenty of bolts going straight into metal. You can use a locking flange nut if you are worried they will fall out.