Creepy White Van - E150 aerodynamics

[Merlyn2220]

I started a thread in the "Central" forum, but was getting no feedback on aero mods. So I've moved the aerodynamic portion of the thread here for suggestions/complaints/criticism (mostly criticism ). Here's the basic first post, then I'll follow up with current modifications as I go.

My hobbies are Ironman-distance triathlon, building old Mustangs and racing Miatas, I really needed a do-it-all car and a Fit just can't haul 4x8s, carry big blocks or tow a 5000lb trailer. Although a pickup might end up more aerodynamic with a proper tapered tonneau cover, it's just impractical in Floriduh where it rains nearly every day from April to October. I picked up the company's old 1995 E-150 with 31k miles but it has the worst FE engine/tranny combination of 300 I6 and 3spd C6.

Here's my current no-compromise list:

1) Must be able to tow 5000lb or more. This will require a large hitch hanging off the back, which is probably horrible for aerodynamics.
2) Must be able to carry 1000lb or more. As with the towing capacity, this will mean big honkin’ tires with high load ratings. That’s a rolling resistance and aerodynamic compromise, but it’s necessary.
3) Must keep the ability to carry 4x8s flat in the back, preferably 4x10s.
4) Doors must be able to open fully (about 90 degrees) to allow backing up to loading docks, forklift dumps into the bed, etc.
5) Must improve blind spot vision. Even with the stock 3-point towing mirrors you can fit a truck in the blind spot, not to mention a Miata, motorcycle or a bike.
6) Without a doubt the handling must improve, right now it’s like driving a 5000lb pig wallowing in mud.
7) Cannot use a trailer-based tail, it’s already so long that it’s tough to park.

Initial plans are for:
1) Replace the huge 3-point mirrors with later year stock paddle mirrors (with blind spot mirror) and possibly passenger side camera and small spot mirror.
2) Side skirts to fill the huge gaps.
3) Improved headlights and DRLs over the OEM 4x6” sealed beams.
4) Adding anti-roll bars to front and rear. The CG is relatively low in this van, but it came stock with no front or rear bars…yikes!
5) Replace stock 225/75/15 tires with higher load + larger diameter in back (lower cruising RPM) and wider/lower profile in front (better handling).
6) Full belly pan
7) Rear skirting around the hitch – possibly extending the bumper to smooth airflow
8) Front airdam
9) Remove FM antennas and use an internal glass-mount or whip antenna
10) Weight reduction (if possible) though it’s not a critical factor. It’s already over 5000lb, so a 100lb savings is only 2%
11) Electric fan replacement for hydraulic/viscous fan head
12) Eliminate bizarre air pump system for simplicity. If it eventually kills the cat I’ll just buy a new one for $65.
13) Exhaust change to 3” from 2.25”, probably a cat-back setup.
14) Stiffer rear springs and/or helper springs to improve load carrying capacity
15) Rear partial shell taper, keeping in mind 90 degree door opening requirement

And yes, the van's nickname really is "Creepy White Van" or "Creeper Van." The van had some mold growing on the side when I bought it, and friend of mine was so kind as to write "FREE CANDY" on the side in 4 foot tall letters. I had to pressure wash them off...but the name stuck!

[Merlyn2220]

So one of the first mods I did was removing the monstrous 3-point towing mirrors. It was unbelievably loud when I first started driving it on the highway, and I could barely go 70mph, while drafting, at full throttle....downhill. I couldn't keep up with highway traffic unless I lucked out and found a truck to draft. I yanked the passenger mirror and installed a bullet-style camera. I have a backup blind spot mirror inside the door, and wired the camera to a cheap Pyle 8" LCD monitor that I picked up off of fleBay. This drastically reduced the wind noise.



I scored an OEM Ford paddle-style driver's mirror from a 2003+ E150, and drilled a couple of new holes to mount it. It's the same shape as the 1990s mirror mount area, just 2 holes don't line up. These two changes did not improve my mpg, because instead of struggling to keep up with traffic I was suddenly able to drive 70-80mph without being at full throttle or going deaf.

[Merlyn2220]

One of the first things that I did was try to reduce the highway RPM a bit. It was running pretty high at 70-80mph, and the 285/70/17 Grabbers are 15.6% larger circumference than the OE 225/75/15s. So 3000rpm => 2600rpm. Interestingly enough, this made NO change to fuel economy. I was averaging around 13.6mpg before the change, and the two tanks afterwards were 13.6 and 13.7mpg. This is probably due to a couple of things:

1) Unknown rolling resistance changes by a few percent, 225 vs LRR 285s.
2) Substantially higher aero drag, both due to section width and due to a big chunk of the tire sticking out of the fenderwell further.
3) Lower engine speed = closer to torque converter stall speed = possibly higher losses.
4) Lower engine speed might not = to significantly better engine economy, even though it is in the "sweet spot" in the torque curve.

You can see how bad the aero performance is in the photo in the previous post. The wheel does actually stick out a bit, I had to hammer-roll the inner fender well so it didn't cut down the sidewall when heavily loaded!

[Merlyn2220]

After messing around a bit with the mirrors and antennas, I was consistently in the 14-ish mpg mark. I tried removing the "cold air snorkle" but all I noticed was an increase in noise level and a decrease in throttle response. No changes in MPG, so I reinstalled it.

The one thing I did that I know improved fuel economy was the driver's side front fender flare. I hit my highest overall MPG when I had the flare finished, at 15.5mg. Unfortunately I don't have any decent photos of it, just this one from when I bought new front rims in December and had to redo it!



I had also started on a driver's side bellypan, you can see the front section with coroplast.

[Merlyn2220]

I'm reasonably certain that the bellypan was a net negative to fuel economy, and I'm not 100% sure why. I went from 15.4mpg before it back to the 13s with it. Unfortunately I don't know for sure, since the fuel pump died in the middle. It had been stumbling at tip-in throttle for a while, but then it started stumbling really bad at idle and slow cruising. It turns out the pump was only putting out around 25psi. So I cut a hole in the floor of the bed (instead of dropping the 250lb full gas tank) and replaced it. I was immediately back into the mid 13mpg range, probably because it was actually spraying fuel when I stepped on the gas. It is likely running richer than before, since I'm sure the pump was at a marginally effective ~30psi for a long time, instead of the 40-50 that it should be. Here's a couple of pics of the belly pan:

[Merlyn2220]

At some point I will go back and remove the driver's side axle-axle bellypan, and run a full tank of gas without it. It's not too difficult to remove, since it is held on by rivnuts. I've just been working on other parts and haven't gotten around to trying it. The next thing that I did was build a really poorly designed rear shell/taper...with NO TAPER!!! I had a bit of taper to the side, but the spray foam bulged it out, and because I built the top first, I didn't have any vertical taper...especially at the edges! So learn from these pictures and DON"T DO THIS! It took 4 days of work to make this mess:

[Merlyn2220]

You can sort of see in the 3rd picture, the flare actually goes OUTWARDS near the top. Fortunately I realized my mistake and only partially finished the passenger side before stopping. I've since hacked it up and tried some other tapers, and will have more pics and MPG results later. In the meantime I was sure that the front wheel flare helped a lot, so I started rebuilding the flare for the new 20s. Rollin' on spinnaz!!!







That big white vertical cylinder is a jacking post, welded to the frame. I made them for all 4 points, and welded a "cup" to my stock jack, and it works remarkably well!

[Merlyn2220]

I continued down the side, boxing in the doors and keeping the contours nice and smooth. The build is various thicknesses of styrofoam, glued together with Loctite PL 3X Premium urethane adhesive. I tried 3 or 4 different types, and the generic construction adhesive was by far the best. Most others won't cure with 2 solid surfaces, or have good initial grab but then fall apart 5 minutes later, etc. This urethane is a moisture cure, so if you are gluing two non-porous surfaces (foam and fiberglass sheet) you just spritz a light mist of water on it, slap it together and tape it down.

Here's the door buildup:


And the fiberglass sheet skin over the foam buildup to the rear wheel.


And the finished, rough sanded side skirt!


I've had to do some touchup where the tire rubbed, but otherwise the side skirt was responsible for a 1mpg improvement, from ~13.5mpg to 14.6mpg. The worst tank of gas was during construction, where I had a DTM-looking square cutoff behind the front wheel. 13.1mpg, ouch! One good side effect of the layers of foam is excellent sound damping of road noise, it's incredibly quiet now!

[Merlyn2220]

My new MPG was somewhat short-lived, because installing the giant hitch (Draw-Tite Class V 41906) hanging off the back both added 60lb to the van, and also totally ruined any chances of having nice clean airflow off the back. It took noticeably heavier throttle on the highway, and went back from 14.6mpg down to 14.0mpg. I'll figure out a way to smooth airflow around it, it'll just take some pondering to get it right!

Adding the rest of the side skirt behind the driver's rear wheel dropped my MPG yet again, but I think I know where I screwed up. I copied some of the geometry of the Volt, Prius and XL1, but utterly failed to keep the maximum departure angle in the 10-12 degree range. The exit taper is around 25 degrees, which is absolutely the worst possible choice! So while it's nice and smooth and looks pretty neat, it's not very effective. 14.0mpg dropped to around 13.7mpg with the rear wheel flare in place:

Outer foam all glued in place!


Some CAD (Cardboard-Aided-Design) of the behind-the-wheel aluminum cover, intended to protect the AC and heater lines for the rear and allow for easy access:


Inner structure with rivnuts and trimmed foam:

[Merlyn2220]

Bondo skinned over the top of a layer of fiberglass. Bondo goes over the foam, then angle-grinder'd flat-ish, glass cloth (2 layers) or mat (1 layer) and then more Bondo over the top:


And it looks pretty reasonable, even if it's not actually aerodynamic!