Front splitter

When Is a front splitter useful? Autocross? Track days?

Do you need to run rear wing to balance ?

I was looking into this yesterday.

Seem to be more useful at higher speeds (70+). That said, enough national-level autocrossers use aero that it must do something other than increase their drag. They wouldn't do it if it just increased drag. Would quite probably be helpful at track days. Adding effective aero in front will prompt subsequent upgrades elsewhere; rear spoiler, uprated suspension to handle the extra "weight" at speed. There are lots of good books on the subject, and if you're working on a commonly-raced vehicle, there's probably someone else out there who has posted on other forums with these questions specifically for your vehicle.

Now I'll shut up and see what someone who knows what they're talking about has to say.

A splitter (or any aero) will work at pretty much any speed if it's big enough and has enough angle. The flip side: something big enough to work at, say, 40MPH will be a real problem at, say, 80MPH. So design has to be matched to whatever your intended use is. Per did a splitter on the front of his B Mod LeGrand, maybe he has some insight to share. There was also a GRM article series on that same car which covered the aeros.

Mark Huffman's D Mod Elan S2 showing the splitter and rear 'flap' or spoiler(wings are not D Mod legal).

From what Ive read (admittedly not that much), a splitter is not as effective without an air dam to create low pressure under the car - the splitter makes the dam more effective. It may be better to just have the low dam rather than the splitter for lower speed racing.

I'm more interested in finding support rods for them. The local "performance shops" don't carry them. SURPRISE!

Probably have to make your own support rods. IIRC Huffman's car uses cables, that way if he hits the pavement with the splitter it doesn't destroy the bodywork. It definitely has cables on the rear flap, or spoiler, or whatever you call it.

In reply to Curmudgeon:

Good idea. Make them adjustable to... Back to the drawing board...

Woops, a question by the OP that hasn't been addressed: splitter etc design is also based on what you are trying to 'fix'. As in: if the car has a low speed understeer problem, then a splitter is probably not going to make much if any difference. It's certainly possible to have it help, but the thing would be so big that it would bring on another whole set of problems, not the least of which is it creating tremendous drag at higher speeds. You'd get more bang for the buck through suspension, tires, etc.

Now, if the car steers fine at low speeds but at higher speeds starts understeering then a splitter may very well become a viable tuning tool by adding front downforce. It's the same with a rear spoiler etc. I added a rear spoiler to the Abomination (now Toyman's car) because at higher speeds (90+) the rear of the car got squirrely. Along with the squirrely feeling it was possible to feel the rear of the car rise. That's what told me it needed some sort of rear downforce.

It doesn't do much of anything at low speeds because the windshield and the big noggin screw up the airflow. But it definitely made a high speed difference!

N Sperlo wrote: I'm more interested in finding support rods for them. The local "performance shops" don't carry them. SURPRISE!

I bought 4' lengths of 1/4" aluminum rod, cut to length and threaded the ends. Easy and a perfect fit every time.

N Sperlo wrote: I'm more interested in finding support rods for them. The local "performance shops" don't carry them. SURPRISE!

Most hardware stores sell "Turnbuckles". Adding one of these to each support cable can make tweaking the angle easy - raise it up for loading ramps, lower it for racing. A bit of piano hinge as the mounting point of the splitter to the car can aid in this.

How far off the ground should it be. I have the factory front lip on 240sx

lower is better, but dragging on the ground constantly doesn't lend itself to longevity.

Longacre makes support rods for those who want 'em. Summit has them in stock.

If you are looking for rod ends, turnbuckles, clevis or a bunch of other things adaptable to cars try http://www.midwestcontrol.com/ I have used them and they ship quickly and pricing is better then some of the race shops.

How far off the ground? Hmmm. I think a very low splitter would be more efficient, right up to the point a bump ripped it off the car. A splitter lying in the middle of the course is highly inefficient. So my suggestion: see how much suspension travel you have at the wheel, then add 1/2" and there's a good place to start. That way when (not if) the suspension bottoms it won't rip it off.

You need to check the rule book too, if you are running a particular class. IIRC the D and E Mod rules have a spec for how far the splitter can stick out past the body line as viewed from directly above and (again IIRC) it can't be any wider than the widest part of the car's front bodywork.

Here's how low it should be

http://www.gotbluemilk.com/web120331/037/imagepages/image19.html

Keith wrote: Here's how low it should be http://www.gotbluemilk.com/web120331/037/imagepages/image19.html

A serious question: what changes between that picture and when you're running the Targa?

Also, I was looking at the specs on your website the other day, are you currently running without sway bars?

Just curious.

Well, the rain is the same...

That shot has the car in track mode. It's 2" lower (that's no exaggeration) and running about 40% more spring rate. I also change the sway bars for a bit less oversteer - I had it set up quite loose for the Targa. I'm also running Toyo RA1s in the picture as opposed to the R1R I ran in the race due to regulations.

The car's developed further since the race, too. It now has a different cold air intake (stock LS7 Z06, actually) which led to the deletion of the NACA duct on the headlight and the intake on the driver's turn indicator. The splitter is a new addition, as is some under-nose aero work. Brake ducts have also been installed, something I should have had in the race.

But it's still got full skid plates, a rally computer and everything else it needs for the Targa. I could put it back into full rally mode in an evening.

Back to splitter talk - Competition Car Aerodynamics by Simon McBeath is a good, easy to understand read with lots of good visualisations. Recommended.

We have a gentleman in AI locally (NASA American Iron) who put a low front air dam on, and proceeded to trim it down by driving around the track, scrapin as he went. Sounded aweful for a few laps, when he didn't hear it anymore, he trimmed it up and added a splitter.

One quick thing to point out. A splitter almost always improves drag.

Here's the splitter acreage hanging off the front of the Radical. Note: The previous owner bought this fantastic thing that was a gazillion dollars. I had it apart to vacuum bag a number of repairs, particularly where I collected a big chunk of formula vee bodywork at SCCA school last year.

I see lots of splitters made of Alumilite - it's tough and pretty light. Plywood is good, done correctly. This carbon thing weighs nothing - it's made on a Nomex honeycomb core - but it drags on everything so I've got sliders on the bottom/front corners made of 1/4" UHMW.