Grassroots Splitter

The shark nose of the ZX2 lends itself particularly well to this little project.

It's made out of good ol' aluminium. Made to street-prepared rules, which means that the splitter is under the profile of the bodywork when viewed from above.

There will be additional bracing (Longacre) added to the two shown in the photos. They will be almost directly under the headlights.

More to come, including the ploycarbonate spoiler out back...

Nice !

Thats awesome!

nice work

Very neat work! Please post a build thread - I would love to do that for the Manic Miata.

FSP_ZX2 wrote:

I am interested in doing this too and have a serious question.

Wouldn't the plates you have tying the splitter to the dam at the ends be very disruptive to the airflow, therefore spoiling the effects of the splitter?

Not really. Think about the front of the tire - at 60 mph, your air meets a surface that's moving down at 60 mph. That pulls the air down and then you get a couple of really strong vortices heading out from the tire/ground interface. Much better to "shield" the tire from the air. Adding a vertical end plate (if allowed) will help too. You want high pressure on top of the splitter.

I've built one very much like this. A couple of suggestions.

• Canards. Very effective. These guys added considerable front-end grip.

• Consider using cable instead of Longacre rods. Cheap, light and it lets the splitter move upwards if you bump something. For the splitter/cable interface, I used some blind nuts and an eyebolt. To give the eyebolt more strength, I welded the little open piece closed - probably not necessary. If I ground out the splitter, the replacement hardware is inexpensive and there's no damage to the bodywork.

This front end setup was able to balance the very effective wing hanging off the back of the car.

Thanks for the tips, Keith.

I'm not sure that canards are allowed. They're specifically allowed in Street Mod, but there is no mention of a canard allowance in SP.

A spoiler/splitter may be added to the front of the car below the bumper. It may not extend rearward beyond the front most part of the front wheel well openings, and may not block normal grille or other openings, or obstruct lights. Splitters may not protrude beyond the bumper. Openings may not be used for the purpose of ducting air to the radiator or oil cooler, but they may allow air to flow through a permitted oil cooler provided no ducting is used. The spoiler may not function as a wing.

In reply to FSP_ZX2:

Very nice!

Keith Tanner wrote:

Hey, is that a step?

Very cool.

We use PolyMetal splitters on our racecars. Inexpensive (race wise) since we go thru a good number of splitters. We also use 5 Star Body braces as our splitter struts. They are adjustable with a 7/16 wrench. Similar to this:

http://pitstopusa.com/i-5070467-allstar-performance-spoiler-support-6.html

If you hit something, will it rip off the entire bumper, or just the splitter? I can't tell from the pictures.

WILL SOMEONE PLEASE MOUNT A GOPRO ON THEIR SPLITTER AND THEN DRIVE THROUGH SOME WATERMELONS AND PINEAPPLES AT SPEED PLEASE?!?!?!?

Thank you.

unevolved wrote: If you hit something, will it rip off the entire bumper, or just the splitter? I can't tell from the pictures.

About the most we plan to hit are cones--it's a dedicated autocross car. Might see a few HPDEs as well, but that is it...

Why was I thinking about firewood?

I would love to build one of these for the Scirocco but does it actually make a noticeable difference on an autocross coarse? Also it would be awesome to see some of the steps to build one.

i love the looks. thinking about one for the 64 elky, ut im pretty sure that the aero advantages are offset by the fact that it is, after all, a 64 el camino.

Dusterbd13 wrote: i love the looks. thinking about one for the 64 elky, ut im pretty sure that the aero advantages are offset by the fact that it is, after all, a 64 el camino with no engine.

Hope it's not too soon to make jokes.

93EXCivic wrote: I would love to build one of these for the Scirocco but does it actually make a noticeable difference on an autocross coarse? Also it would be awesome to see some of the steps to build one.

We mocked it up in cardboard (find a refrigerator box or similar) and duct tape. Transferred the patterns to aluminum and used a jigsaw. Lots of time cutting and fitting everything, but not difficult or mind-numbing in any way.

Its hard to quantify the "difference", but, yes, it should make substantial downforce even at 50-60mph. Stick your hand out the window at those speeds, and change the angle-of-attack. Can you feel it? There is a lot of air that will be "packed on" the splitter...that air has to go somewhere.

In reply to FSP_ZX2:

How did you get the bends on the edge of the bumpers? Have you run an autocross yet with it?

93EXCivic wrote: In reply to FSP_ZX2: How did you get the bends on the edge of the bumpers? Have you run an autocross yet with it?

Not run yet. Still have some more finishing to do...

Which bends? Not sure I understand what you mean...

pinchvalve wrote: WILL SOMEONE PLEASE MOUNT A GOPRO ON THEIR SPLITTER AND THEN DRIVE THROUGH SOME WATERMELONS AND PINEAPPLES AT SPEED PLEASE?!?!?!? Thank you.

I have a GoPro mount in the nose of the car, and watermelons are in season.

Plywood would be less expensive, it might be fun to play with that.

Here's a step-by-step of mine. FSP has a more stock car so his experience might be more applicable to most. In terms of effectiveness, our local track has an average speed of about 50 mph and a max of about 75 for this car. The difference between the small and large splitter here was notable.

Aftermarket airdam.

First step was an undertray. Not needed for most stock cars.

Shaping the splitter - this is easy enough. If your class does not allow you to change the outer dimensions, I'd use a plumb from the nose to determine the shape. This is my first one, it was about 2.5" deep. The newer one (with the cables) is more. I attached the splitter to the undertray and the airdam with rivnuts. The car's too low to get into the trailer with the splitter in place, so it had to be easily removeable.

Attaching the original Longacre struts.

The wheel spats. They're attached to rivnuts in the wheel arches and on the splitter so they can be removed.

Canard fab. They weren't really intended to look quite like this, it's what happened as I bent them up Riveted to the bumper, rivnuts to the splitter.

FSP_ZX2 wrote:

93EXCivic wrote: In reply to FSP_ZX2: How did you get the bends on the edge of the bumpers? Have you run an autocross yet with it?

Not run yet. Still have some more finishing to do... Which bends? Not sure I understand what you mean...

Sorry yeah that didn't make sense. I was really talking about the air dam on the bends.

The splitter matches the curve of the bodywork (including the inner bodywork of the nose/fascia. It was cut to match--there is no undertray behind the splitter like on Keith's Miata. The air dam was mocked-up out of cardboard as well, but it is a pretty thin gauge...it fits the curve/radius of the back of the splitter/"floor". There are tabs on the "floor" that the dam is riveted to--but they were not done in the picture, the tabs held things in place for the purpose of the photos.

FSP_ZX2 wrote: The splitter matches the curve of the bodywork (including the inner bodywork of the nose/fascia. It was cut to match--there is no undertray behind the splitter like on Keith's Miata. The air dam was mocked-up out of cardboard as well, but it is a pretty thin gauge...it fits the curve/radius of the back of the splitter/"floor". There are tabs on the "floor" that the dam is riveted to--but they were not done in the picture, the tabs held things in place for the purpose of the photos.

Ok that makes sense. Thanks. Look forward to hearing driving impressions. Are you also run a rear spoiler?