Poor Man's Aero Package, Version 2

[Jack Olsen]

My fabrication skills are, well, kind of sloppy. Fortunately, this means I limit myself to making stuff that only bolts on for short amounts of time. I've been playing around with aluminum skirts in front and the sides of my car, and fabbed up a set today that go a little bit lower than the previous ones I was using.

Iteration 1:



Iteration 1B, with revised front:



I figured I could go a little lower based on pictures of the car in turns, where it seems the sides don't compress down as much as I thought they might.





Obviously, you can't run this stuff on the street (no good reason to, either). This means the three sections each have to fold or come apart into two pieces so they can fit in the car for the drive to the track. This means a big ugly hinged joint on the side (but what are you gonna do?).

I'm planning on testing them on April 13th, with ACRA at Willow Springs. If I get my data logger issues sorted out by then, I'll try to A-B some laps to see if there's an easily-measurable effect.

Any suggestions on tweaks to the basic shape? They get painted later today.

Iteration 2:

[Bill Verburg]

Looks good, deeper/closer to the ground is always better, a projecting splitter(most rules only allow to the forward most extension plane of the bumper) wil also help

Do you need the big holes in the spoiler for cooling?

I would be tempted to have a full track only front end, along these lines, flat clean w/ only the necessary holes placed as close to the car ctr line as possible

[TimT]

get some hard rubber, or ABS or PVC plastic, and rivet a strip to each.

On our car we used rivnut, and small button head screws to secure the strip. I made a number of different depth strips, so we can determine which depth lip offers the best performance.

The car currentlly has a much deeper lip on it, only about 1" clearance

[DustinTarditi]

Maybe have the forward side skirt overlap the rear side skirt so the seam doesn't get air intrusion at speed (and shear or pull the skirt)... sort of like the overlapping shingles on a roof.

[Noel]

Looks good Jack. I'm curious to know what the data shows. One additional thing to keep in mind is that your brake temps may increase since you are cutting the airflow to your brake cooling diverters. It may be worth it to also measure brake temps with and without the spoilers.

Looking forward to the full report. Thanks for sharing.

[DJQ911]

Fit some rubber skirts below your aero package. I'm sure after five laps they will have found their optimum shape.

[Tspringer]

Do these skirts really make much difference? Did you get any real measurable gains in lap times after installing the skirts?

[brcorp]

Well the bichen Camaro is in its place......

[Jack Olsen]

I need the front holes for my oil coolers. The downside to a track-only front piece is getting it to the track (no trailer), and keeping it from tearing off in its entirety if I go off track. The later versions of my front splitter have a 3-inch lip in front, but then a straight-down skirt below that. It's not ideal, aerodynamically, but it can take an impact with a berm and simply fold back, rather than the type I had in front that was painted red, where one impact would pull the whole thing off.

I'll try a rubber extension after the first test, since I want to proceed carefully. I'd hate to have a lot of pieces of aluminum flying around in turn 8 at Willow Springs.

I'll keep an eye on brake temps.

Thanks for the input. I'm thinking about mounting a lipstick camera on the testing day to see how close they come to the pavement, and also how much they distort at speed.

[ZCAT3]

Why not leave them raw aluminum - it looks pretty cool as is.

[Bill Verburg]

You're discoverring what I learned many moons ago first w/otorcycles then w/ cars and later boats, street compromises track and vice versa. You may be at the point where a dedicated track car is in the cards.

Same here, I have gotten seat time in various Cup cars over the last few years and find that lesser cars are not acceptable any more.

The thought of a truck and trailer is unappealing in the extreme.

[cegerer]

Jack, ya need a couple of extractor blowers powered by snowmobile engines to complete the job.

[RetroSC]

I'll have to agree with the above, the raw aluminum looks kind of trick. The painted red looks like you're actually trying to make them look nice were the aluminum looks like pure function to me.. sweet!

[bigrubberjeep]

Originally posted by Bill Verburg
Looks good, deeper/closer to the ground is always better, a projecting splitter(most rules only allow to the forward most extension plane of the bumper) wil also help

Do you need the big holes in the spoiler for cooling?

I would be tempted to have a full track only front end, along these lines, flat clean w/ only the necessary holes placed as close to the car ctr line as possible

This is a pretty sick front end, I love it - Who is it from?

[masraum]

Jack, I agree, I like the raw aluminum.

I have a simple, light answer to your hinge problem. Don't hinge the side skirts like a door, hinge them like a pair of scissors. It'll only require an overlap and a bolt.



I also agree that you could use some stiff rubber or plastic like the original lip for the front to remove some of the worry, but the Al seems like it may do. It is just for the track anyway.

[Jack Olsen]

I painted it the same color as the aluminum. It takes such a beating that the ability to quickly repaint it is something I wanted. If I left it bare, I'd have to clean it, which would be more work.

[350HP930]

Now all you need is a four wheel downforce measuring system to determine exactly how effective it is.

[911pcars]

Jack,
Dave @ TRE has a point. As you reduce the spacing between lip and road surface, the chances of the road biting chunks off the lip increase, and replacing the nice aluminum fencing can't be fun after a few ripoffs. It seems a sacrificial-type rubber lip all the way around will find it's lowest allowable clearance by virtue of what's left of it after a few laps.

Are floating lips allowed? That is, perhaps a series of interconnecting rubber sections that can "float" just above the road surface. I think the aforementioned Chapparel Sucker Car had this feature. This would take into consideration the roughness of the road and changing ride heights caused by racing-induced suspension travel.

Sherwood

[jyl]

I think you should use a thick strip of bristles instead of the rubber lip on the front air dam. The bristles would conform to the changing ride heights.

The bristles would also sweep grit and gravel etc off the track. This would give your tires a clean surface for the best possible traction, a very tricky advantage over your less creative competition.

A spanking clean track surface would also allow you to reverse the cooling fan for home-grown ground effects. The main objection to this previously was that the engine would get dirty (must be a buncha concours weenies here).

The material for the bristles will be important. I suspect German horsehair will be the best.

Hey, they probably thought Nobert Singer's ideas were crazy too . . .

[bigrubberjeep]

Jack - I just remembered, do a search online for the 1985 Dodge daytona, I recall it having side skirts made out of some medium to hard plastic. This might give you some insight in to the durability issue.

Just my 2cents