Splitters and air dams

[Andy Bettencourt]

We have developed a product for RX-7's, but we did it with a primary goal of managing cooling. It does a good job smoothing out the air around the front tires but we have no data on downforce, etc.



I would love to have people post pics of their solutions. We are about to develop a Miata solution but the difference is that it's primary fuction will be aero. Any hints, hits/misses would be great - not car specific, just trying to collect some data and opinions.

Thanks!

AB

[Greg Amy]

Something interesting to read... (see attachment). - GA

[charrbq]

Wow! Good article! All I could add was that a splitter on my air dam increased the turn in so much that I had to soften my rear shocks to compensate for the abrupt rotation in a sweeper.

[Joe Camilleri]

Here's one on the classic Mk1 Scirocco spoiler.[attachmentid=267]

[Bildon]

OK that's enough of that Greg! Don't be showing everyone where to get real information!


2000 Splitter
http://www.bildon.com/pub/PIC00296.JPG

With a little lift of the tail to diffuse
http://www.bildon.com/pub/turnbuckle.jpg

[flaboy]

wow...is that it legal??and if so where can i get something like that for my rabitt?


Tim

[lateapex911]

Sure it's legal, as long as it fits the plan profile and stops in the proper place.

And its strong too! look at it hold up the car!

Where to get?? Looks like Lowes? Or is it HD? LOL....

[tom91ita]

is there any concensus on the proper material of construction?

plastic? aluminum? paneling? masonite?

what thickness?

tia, tom

[MMiskoe]

I've been running a a similar set up to the Bildon model on my Nissan for a while now. Made out of 1/4" thick plywood. The thought process was on mtl selection was that it is cheap, easy to come by, easily formed and if it were to get demolished it won't splinter into parts sharp enough to cut down a tire (at least I don't think it is sharp enough to do that, haven't tried it). The best reason I came up w/ was seeing Trans-am cars, Formula Atlantics and Grand-Am style endurance cars all using plywood. I figured if its good enough for them, it ought to hold up for an IT car.

As far as the down force generated - yes it is noticable. The front feels much more connected and secure while going over hill crests (NHIS turn 8) w/ it on. As far as how much force - it being 1/4" plywood about 14" front to back and supported about 24-30" apart in front (either side of the radiator) I've witnessed 3 to 4" of deflection. When I'm trying to re-create that in the shop w/ my hand I am amazed how hard I have to push.

Similar to the way a Trans-am car is set up, mine is hinged at the back so I can raise it & tie it up for loading on /off the trailer. I secure it at the right height so it won't flap while on track.

[bldn10]

Matt, I remember the first time I saw a splitter on an IT car - it was the famous 70 SpeedSource RX-7 at the ARRC back in the 90s. I went over and scoped it out and was amazed to see that it was made of wood. Years later I buy a used SS car and the splitter is demolished at Barber in 7/04. Then I discovered that the "dive plane" is not your typical Lowes/HD plywood - it is Jabrock, some kind of high pressure-treated, impregnated plywood that is hard as nails. That is what is used for splitters, skid plates, etc. on pro cars. I looked into getting some and found that it was like $300 for a piece smaller than standard 4 x 8 plywood. So much for that. I made one out of 1/4-5/16" BC plywood and it looks good and has held up well over a season and a half. Do not use crappy CDX plywood - the leading edge will splinter. Or, as I did on a previous car, slit some fuel hose lengthwise and staple it over the leading edge as a bumper guard. It protected the edge and looked pretty cool too.

Can you explain your hinge in more detail? What secures the splitter in front?

[Greg Amy]

...I remember the first time I saw a splitter on an IT car...[/b]

Me, too. It was on Tom Blaney's CRX about 3 years ago; he had it in the bed of his pickup truck about to leave. I remember looking at it and thinking to myself "that cheatin' sonova..." Then I went home and read the rules, and recognized he was RIGHT!

I was never particularly convinced of the value of a splitter on our cars (the airdam was obvious), but I've gotten enough positive first-hand accounts such that I'm fabricating one now for my car. We'll see, eh?

[Bildon]

3 years? You haven't been paying attn. :P People have been running these for a long time in IT.
Another nice bit to exploit is your fuel line guard. D.1.b
It can be WIDE and flat and run the length of the car. Also if needed it can be very heavy.

[JamesB]

Makes me wish my golf wasnt a small bumper car.

[Greg Amy]

3 years? You haven't been paying attn. :P[/b]

True, to a degree. I raced IT from '84-ish to '88, switched to SS for '89-92, then quit racing altogether. Rejoined SCCA '00-ish, hit the track again for the first time 2002. By then the IT rules had devolved from fairly straightforward street mods into the orgasmic broiling flaming pit of Satanic loopholes...

[RX-Heven]

LOL, that is a replica of a Demonspeed splitter for a 2nd gen RX-7 that I and others have been running for several years now.

However, it is good to know that there is an alternative to the pricks at Demonspeed as they are thieving cocksuckers.

That splitter made a huge difference in cooling, especially with my fmic since I was able to direct fresh air to the radiator below the ic. It is all boxed in and sealed with aluminum behind the spltter too.

There are pics in my sig.

[shwah]

If you take your time you can come up with a design that has a lot of horizontal area within the legal envelope on a small bumper or no bumper car. Mathis has a pretty good setup on the front of his car that certainly looks IT legal to me, as long as you set it with the lowest peice even or above the bottom of your wheel rim. We do have molds, might be able to talk Rob in to making some for sale.

Crap - forgot about the BS slow upload connection here at work. I will have to put some pictures up tonight.

If you take your time you can come up with a design that has a lot of horizontal area within the legal envelope. Mathis has a pretty good setup on the front of his car that certainly looks IT legal to me, as long as you set it with the lowest peice even or above the bottom of your wheel rim.

[MMiskoe]

[attachmentid=277]
Didn't know that about the plywood, had I konwn, I would have still done what I did. I did use the higher grade stuff & for its cost & the amount of abuse it has taken I cannot complain. The original intent had been to get more air into the radiator instead of having it just go under the car.

This is the best picture I have of it. The car has a pan between frame rails, below the radiator, but set back quite a ways back from where the bottom of the bumper cover ends. The hinges are attached to that pan so they are a good 10-12" behind the bumper cover. The plywood ends at this pan, the hinges attach to the back edge of the plywood. Since the bumper cover sticks out further, the plywood follows that contour and leads the bottom of the bumper cover. Up inside the bumper cover are mounts for fog lights w/ nicely placed threaded studs. A small pc of aluminum angle iron (horizontile) bolted to the studs recieves a pc of threaded rod (vertical). The threaded rod has nuts top & bottom that can be adjusted to raise or lower the leading edge. At the end of the day, they get backed off and it gets raised so it hits the bumper cover bottom edge and clears my trailer ramps.

My biggest problem with it seems to be stepping on it while working/walking around the car.

[seamus88]

[attachmentid=278][attachmentid=279]Here are pictures of mine. I made a drawing in CAD and had my friend waterjet the aluminum. The one in the picture has been repaired twice.So the original pop rivet tabs are missing.You can see the little "L" brackets I used in there place.The duct work is just standard gutter drain parts that connect to sump pump hoses attached to the car.I have to take it off to tie down the car.

[bldn10]

"Another nice bit to exploit is your fuel line guard. D.1.b
It can be WIDE and flat and run the length of the car. Also if needed it can be very heavy."

Whoa, Bill, are you suggesting what I think you are? A flat piece of metal attached to the underside protecting the fuel line but also acting as an undertray?

I just do not read that rule to allow that. All it says is that the fuel line may be "given additional protection." It then goes on to talk about metal or metal braided lines through the passenger compartment. I think all it means is that you can use metal or metal braided lines or otherwise wrap the lines in some kind of protective sleeve - not weld or bolt some piece of metal to the chassis. Has anyone actually done this? I like the idea; I just don't think it will pass muster.

[shwah]

A metal plate bolted to the bottom of the car is 'additional protection'. However a metal plat along the whole bottom of the car for this purpose would fall under the allowed modification performing a not allowed function. Otherwise it is a smart interpretation of the rule IMO.