Rear Wheel Skirt using water heater drain pan

[justpassntime]

Nice job on the skirts. It always makes it easier to use something that is close to what you want already made.

I always thought a satellite dish would work nicely. Especially Dish Networks high definition dish (actually it's the old DirecTV triple sat dish). They are more the shape of a wheel well.

I was also thinking that if you made a louvered vent in the wheel skirt, about where the front edge of the wheel rim would be, that it may help with airflow through the wheel well. Not sure if this would help anything or not. Any thoughts?

[cfg83]

Hello -

Last Monday I finally finished the passenger side skirt. It took longer because I had to carefully match up (eyeball) the attachment holes to match the driver side skirt. I am happy with the results :

Passenger and Driver Side :


Driver Side Close-up :


To solve the size/gap problem, I just added black spongy insulation tape :

Driver Side detail of spongy insulation tape :


Here is the splash-guard front air deflector. I will replace this with a better picture later :

Driver Side Front View with splash gaurd and Rear View :


Problem: I have noticed that the plastic is flappy on the bottom where I cut it in half. While I haven't seen it hit, I see little dents in my center lug-nut plate. I don't mind this, but I think this could cause "negative aero" if it starts vibrating at speed X. I should do a film to find out if it is flapping but I am too lazy right now. I know I can solve this with rigid metal strip.

CarloSW2

[cfg83]

Hello -

Here is another issue I had with the installation. I'll start with this picture of idealized top-view cutaways :

Wheel Well Fitment :


Here are their explanations :

1 - If the wheel well and water heater pan are an exact match, you get a perfect fit. This is the ideal.

2 - If the wheel well is a little bit too small, then you can get a situation where the drain pan "bows out". I think this is next to ideal and in fact the shape we usually incorporate in wheel skirts anyway.

3 - If the wheel well is a little bit too big, then attaching the sides of the drain pan can cause it to "bow in" and hit the wheel. This is in fact what happened to me.

3A - My solution was to add rubber spacers between the pan and the wheel well in order to make it closer to image #1. The spacers were only needed at the lower connections. There is still some bow, as you can see in this picture if you look closely :

Driver Side Rear View :



CarloSW2

[cfg83]

Hello -

I forgot to mention that I solved the "Ziptie" front connection with screw eyelets :



In this picture you can see the spacers I mention in post #13 (red plumbing washers) :



Here are the drain pans in Home Depot :



As you can see, *metal* drain pans are available. For a person with the skillzz, these could be hammered around the edge to fit better than my plastic ones did. They are also a(n ill fitting and more $$?) short-cut for people that don't want to start with a sheet of metal from scratch.

But I like my plastic because it seems to be less of a threat to the tire and other people.

CarloSW2

[cfg83]

Hello -

Quick update. The wheel skirts appear to be helping my MPG. I have 7 tanks with the new skirts so far. I compared the same number of tanks before/after the skirts were added :



Dividing the After MPG by the Before MPG I get :

44.05 MPG / 42.17 MPG = 1.04458 => 4.45% MPG gain

However, I am not going to claim a 4.4.5% gain. There's just too many other possible factors. If I delete the two worst (sub 40 MPG) tanks of the 7 "before" tanks I get 43.46 MPG :

44.05 MPG / 43.46 MPG = 1.0136 => 1.36% MPG gain

Because of the above, I will only *claim* a 1.36% gain.

CarloSW2

[chuckm]

Thanks for the update! I've been considering doing this mod myself.

[Funny]

Originally Posted by cfg83

I compared the same number of tanks before/after the skirts were added :...

Originally Posted by cfg83

Dividing the After MPG by the Before MPG I get :

44.05 MPG / 42.17 MPG = 1.04458 => 4.45% MPG gain

However, I am not going to claim a 4.45% gain. There's just too many other possible factors. If I delete the two worst (sub 40 MPG) tanks of the 7 "before" tanks I get 43.46 MPG :

44.05 MPG / 43.46 MPG = 1.0136 => 1.36% MPG gain

Because of the above, I will only *claim* a 1.36% gain.

CarloSW2

I want to jump in so you can get another opinion on that unusual math .

You want to effect both sides of that mileage equation so the standard deviation is the same, compare apples to apples.

If you take the highest and lowest (highest sigma) off of the before and after tanks, then you come up with something like this:

After skirts: ((44.24+42.3+43.11+45.35+45.25)/5) = 44.05 (left off 45.94 and 42.17)

Before skirts: ((44.57+44.52+42.21+41.01+39.13)/5) = 42.288 (left off 45.01 and 38.71)

((44.05-42.288)/44.05)*100 = 4.00%+

Just don't want you to be short changing yourself, because you were artificially increasing the before tanks without doing anything to your after.

[cfg83]

Funny -

Thanks for the statistics. I usually short-change myself so that my claims are solid. Based on your computations, I think I will claim up to 4% gain, depending on driving conditions (city vs. highway).

CarloSW2

[groar]

This will motivate me to make my non-cardboard skirts.
I had to change my driving a lot to have a result closed to the one with my cardboard skirts.

Denis.

[alohaspirit]

I think this is a great mod cfg83

hope to see updates

(maybe I should splurge and get 2 pans)