Are side skirts worth it ?

Hi All,

Looking at many over the road tractor trailers I have noticed that many trailers are equipped with side skirts that help fuel economy.

I was wandering around Lowes the other day and found that they sold rolls of pretty thick plastic like landscape edging that I thought would make for good side skirts.... 20 foot roll or black composite edging for $24.98 item number 514744...it looked to be about 3.5 inches tall (I wished it was taller so the skirts would go closer to the ground)

Has anybody here experimented with side skirts? Is lower better or is 3.5 inches better than nothing?

How do you think they would do without modding the front air dam?

For mounting, I was thinking of welding some bolts onto the seam that runs along the bottom of my Jetta (the same seam that the factory jack raises the car from) and then just drilling the corresponding holes on the side skirt for a simple bolt on operation.

Any thoughts and or experience with this?

Thanks

Andrew

Nascar use them for down force etc so they must work???

the more air you can get to your flux capacitor the more cocaine for the diesel fairies.


honestly sounds like more trouble then its worth. you can probably get better results from braking/acceleration techniques. not to mention doing it in a way that doesnt look ghetto fabulous.

For tractor-trailers, any air that gets underneath the trailer runs into a huge and aerodynamically "dirty" obstruction, in the form of the rear wheel and axle and suspension assembly, so it's a decent benefit to send the air around the sides of the trailer instead of letting it hit that obstruction.

For your Jetta, which has a relatively smooth underbody, air that gets underneath the car pretty much goes out the back unobstructed.

In terms of "downforce" it can be a benefit to stop air from getting underneath the car at the front (large air dam extending down close to the ground) plus side skirts (to minimize the amount of air that gets in from the sides) but this isn't necessarily a drag-reduction scheme.

Andyinchville1 said:

Any thoughts and or experience with this?

Thanks

Andrew

Click to expand...

Try it out, but I'd skip too much permanent fixture points, i.e. welding, IMO.

IIRC the side skirts on OTR trucks are relatively V-shaped, bottoms of the V being at front of their trailers, opening up at the trailer rear.

So keep in mind that you would also be pushing the same debris carried in the air
to the rear of your car; water, dirt, gravel, bugs, sand, whatever.....towards significant systems like brakes and suspension components, fuel tank....

OTR trucks have their skirt Vs pushing air out the rear of the trailer section, in front of the rear wheel assemblies.

Do a vid, post it up.

HI All,

Been working (driving alot) and have decided to try to move ahead with this project.

I have been looking for a suitable material for the side skirts and have decided to see if I can buy a sheet of the materials used on tractor trailer side skirts...

I'll update as I get further into this project....

Thanks

Andrew

Andyinchville1 said:

Hi All,

Looking at many over the road tractor trailers I have noticed that many trailers are equipped with side skirts that help fuel economy.

I was wandering around Lowes the other day and found that they sold rolls of pretty thick plastic like landscape edging that I thought would make for good side skirts.... 20 foot roll or black composite edging for $24.98 item number 514744...it looked to be about 3.5 inches tall (I wished it was taller so the skirts would go closer to the ground)

Has anybody here experimented with side skirts? Is lower better or is 3.5 inches better than nothing?

How do you think they would do without modding the front air dam?

For mounting, I was thinking of welding some bolts onto the seam that runs along the bottom of my Jetta (the same seam that the factory jack raises the car from) and then just drilling the corresponding holes on the side skirt for a simple bolt on operation.

Any thoughts and or experience with this?

Thanks

Andrew

Click to expand...

Just a thought. IF I understand what you are saying

Speed bumps where my wife works (and other place 'round here) would be a situation to deal with.

Andyinchville1 said:

HI All,

Been working (driving alot) and have decided to try to move ahead with this project.

I have been looking for a suitable material for the side skirts and have decided to see if I can buy a sheet of the materials used on tractor trailer side skirts...

I'll update as I get further into this project....

Thanks

Andrew

Click to expand...

I don't understand what side skirts are going to do for you.. The air comes in under the car from the front. And like someone else posted, will be an issue on speed bumps, and other perturbations in the road. If you're looking to save fuel, look at driving habits. VW did a lot of aerodynamic testing when designing these cars. Do you have a wind tunnel to study the effects of these side skirts ?

How much of your driving is at high speed?

At less than 40 MPH (65 km/h), I bet these skirts do nothing for you. Something to consider.

Andyinchville1 said:

HI All,

Been working (driving alot) and have decided to try to move ahead with this project.

I have been looking for a suitable material for the side skirts and have decided to see if I can buy a sheet of the materials used on tractor trailer side skirts...

I'll update as I get further into this project....

Thanks

Andrew

Click to expand...

I look forward to seeing the results or hiccups, however it turns out the first time.

Mike_04GolfTDI said:

How much of your driving is at high speed?

At less than 40 MPH (65 km/h), I bet these skirts do nothing for you. Something to consider.

Click to expand...

I do mostly highway driving (delivery work)....only time I'm in town is to pick up and drop off....the rest of the run is city to city (not in the same city).

If you are looking for the biggest "aero" bang for the buck, given that you drive a wagon...

Would be to emulate the other aero-aide - the aero tail.



Your wagon has a large, flat, negative-pressure inducing tail. If you are game, add some aero to that - you would see more gains there than on any side skirt.

Windex said:

If you are looking for the biggest "aero" bang for the buck, given that you drive a wagon...

Would be to emulate the other aero-aide - the aero tail.

Your wagon has a large, flat, negative-pressure inducing tail. If you are game, add some aero to that - you would see more gains there than on any side skirt.

Click to expand...

Ha...great minds think alike!

I want to do that too but side skirts are much easier to do starting out.

Actually, the first thing I need to do is cut the grill blocks out of the Dura Plex I have at the house (got from Lowes) to replace the blue painters tape I now have covering the front grill and all the front openings minus the SMIC air intake and the center opening in the lower valence panel...THAT should help in the looks department big time but I must admit the painters tape has help up very well thus far (been on for several weeks now...and it has survived many thousands of miles including many rains!).

If I can just eek out 5 or 10 percent more mileage I'd be tickled! (using hardware / mods NOT simply adjusting driving methods since I HAVE to drive the limit and then some to make deliveries on time (ironically the more I speed the more I can rest on long runs since the runs are timed).

Andrew

http://evworld.com/article.cfm?storyid=911

Read that.

The back of the wagon is much closer to a Kamm than the cube shape of the class 8 trailer. The Kamm design is deceptively aero by itself.

https://en.wikipedia.org/wiki/Kammback

Was there ever the equivalent of a BlueMotion model of the MkIV in Europe? I assume not, but if so, it would be interesting to attempt to duplicate its aero elements.

There is lower hanging fruit than side skirts. Making the front of car smoother via blocking off grill openings is a good start. Wheel pants for rear wheel well openings may well have some good results. If your running steel wheels than a set of moon disc hub caps.

IMBM but I think shizzler did a lot of mods to his mkiv Jetta to reduce drag: smaller side mirrors, blocking grill openings, under body smoothing. He also has driven a ton of miles so his results would be real world and useful.

Could definitely use the Kamm effect in your design and reduce the back to half at the tail, or add a wing similar to the one in Mike 04's link above.

I really think that the tail is a more meaningful way to do a little.
If it were me, I would play with my IQ and driving habits.

I realize you have time constraints, Modification of braking and acceleration habits can be huge, if you're heavy footed especially!

Given your mechanical preference for modification a hammer mod to move the IQ a bit might be up your alley, or maybe you've done that.

Can't wait to see pics

DeezlMax said:

Can't wait to see pics

Click to expand...

I actually started buying materials for the skirts but I'm having to read up on how NOT to fry electronics when welding the studs to the seam on the bottom of the car.... I don't need a fried ECU or a dead radio because I did something wrong....

It's slow going only because I drive / work so much....slowly but surely I;ll get there!

Thanks

Andrew

Pull the negative battery cable, and ground as close to the work as possible.