2004 MINI Cooper S - Improving Aerodynamics

[superchow]

Hello fellow Northwesterner! One thing I noticed about your car is the rounded transitions from side to the back. It may be promoting turbulence in the wake. Maybe adding a sharper transition ala Chevy Volt, Toyota Prius could produce a cleaner wake without altering the look of the car too much.

Also, consider inflating the tires a little more to reduce rolling resistance. Good luck!

[johnf36]

Yes, the car has a horrible vacuum on the rear. On the second gen cars BMW add a raised section to the c pillar to help. I installed Vg's in this location which helped and I have more to go on the roof

[botsapper]

This classic boat/dog tail was a little off.
Mini Cooper Oscar Mayer Weinermobile on Flickr - Photo Sharing!

[johnf36]

I find this worked better

[johnf36]

Something else is the tires if you have the stock 205 45 17's you could go to a smaller rim with narrow tires. The stock meats are conducive to sticking not MPG

[comptiger5000]

I'd say 205s are a decent compromise. They're really not that wide, although they're not 155 pizza cutters.

[iplaysdrums]

The tires (tyres) are 195/55 R16 (16" rims). I thought about going with smaller rims, but I really don't think they'd fit around the brakes =D. I actually just got new tires yesterday (Bridgestone Potenza G019 GRIDs). Once I get them broken in a bit, I'll experiment with jacking the pressure up. I was floating between 40 and 50 with my old tires, but I want these to last a good long time, so I'll have to monitor things pretty closely. The tread on these tires is deeper than I've seen on many road tires - for a second I thought, "whoa, those are rally tires!"

Loving the pics, botsapper and johnf! I'm thinking more along the lines of what superchow is talking about, though. Someone posted a video about the Volt a while back, and the 5mm "trip device" they have going all along the back of that vehicle has been a big inspiration for what I'm planning. The second stage of the wheel skirts will hopefully extend beyond the rear bumper, flanging slightly at the tip for a clean release. The removable partial boattail/kammback (I really don't like that term, which probably stems from the fact that it's an Americanized [*******ized?] version of Kammtail/K-tail, named after the German guy who invented/discovered it), which I'll be building onto a bike rack (once I get one), will extend back a couple of feet, employing a similar "trip device" to the wheel skirt extensions, and that will take care of the top and bottom of the car. I'm not sure what to do with the remaining couple of feet in the middle - I may go with vortex generators like the ones you use, johnf. Where did you get those, by the way? I've found them a couple of places online, but I'm a very thrifty man, and I want to get the best deal possible.

On the same lines (i.e. - me being cheap), my birthday is later this week, and I plan to use some birthday money to buy a rotary tool (think Dremel), which will greatly aid in fabrication. That said, I don't have the wheel skirts cut yet, but once I do, I plan to attach them using the stock holes in the bumper, possibly even reattaching the existing arch covers over the top, though that might end up looking goofy AND increasing drag. I'll probably put pizza pans on the front wheels (think racing discs, thanks very much to whomever mentioned that a page or two ago), attaching them via screws though the existing holes in the center hubs.

I think I may have mentioned this before, but I want everything I'm doing to be reversible, so in the unlikely event that I sell the car, the new owner won't necessarily have to have a permanently equipped AeroMINI.

edit - apparently we're not allowed to use the word b@st@rd. good to know.

[iplaysdrums]

I've just picked up my first rotary tool, and though I'm still figuring out which cutting wheel works best for what, along with everything else, I have stage one of my rear wheel skirts in about the shape I need to mount them. The actual mounting, of course, is a horse of a different colour, and I may have to modify the arch covers to accommodate the skirts. Nevertheless, it should be a *fairly* painless process, and when I'm done, I'll definitely have one of the more unique MINIs around.

While I was walking around Home Depot after picking up the Dremel, I decided to look around in the building materials, because you just never know what you'll run across. Lo and behold, they have unpainted aluminum gutters for under $6! With a bit of cutting, flattening, cutting, drilling, and cutting, I'll probably be able to use that metal for side skirts and as much of a belly pan as I'll ever actually install. I'm pretty darn excited about that. I'm actually not convinced the belly pan will help as much as some would predict, because it's fairly flat down there anyway. I definitely don't want to cover the exhaust, particularly the cat, and there's not much I can do about the control arms (I think that's what they are - I'm not terribly tech savvy just yet, particularly where the chassis and suspension are concerned) without lowering the car another inch or two, and it's hard enough to get under as it is, never mind how the side skirts are going to affect it.

In preparation for the belly pan, I removed the front airdam I'd installed, so right now my only aeromod is the upper grille block, which is made of tape. I should probably take some new pictures so I'm up to date. Someone yell at me if I haven't done that by next week.

In a somewhat unrelated move, I removed the rear seats today. They add a surprising amount of weight, and I'm working on the rear speakers (which are ridiculously difficult to get to), anyway, so I figured I might as well see what the next tank looks like without them. I don't expect to see a significant change, and I'm going to have to reinstall them eventually, but I enjoy the adventure of making reversible changes.

Speaking of weight reduction, I'm seriously considering this. It's definitely not easily reversible, but it'll save me 20lbs and make the car sound cooler, so there's not a lot to lose here, provided I can find a place that will do it for a good price without ruining the exhaust or the car.

I've also decided against using pizza pans to cover the wheels, because the metal-on-metal could end up marring the wheels beyond repair, and any savings in fuel economy that ruins any part of the car is officially not worth it. Instead, since the plastic from the water heater drain pan (for the wheel skirts) is fairly rigid, I'm thinking something like that would work pretty well. I'm hoping to find something smaller and cheaper to cut rather than another pair of drain pans, but if push comes to shove, I'll just have to go with that.

All in all, things are looking pretty good right now, though I'm leaving the biggest project (the Kamm tail) for a little bit later. For one thing, I'm going to have to spend some serious time designing and consulting to have it be effective (finding the proper angle, getting all the curves right, getting it to fit to the body without damaging the paint, making sure the whole thing is secure, etc). For another thing, I don't have the base for it yet (another shameless plug for the Yakima MegaJoe 3 bike carrier - the thing is solid as a friggin' rock).

[iplaysdrums]

Well, it seems my plans for this project change every week, but I have a couple of major updates: front reverse mudflaps and vortex generators!


These redirect the air that would hit the front tires around the sides.



Detail!




Since I'm not going to be getting around to the Kamm-tail for a while, these should work pretty well as a stopgap, reducing the car's turbulent wake one delta wing at a time.

I may well have the side skirts on by the end of the week.

[AeroModder]

The reverse mudflaps was definitely a good idea, but I'm pretty sure VGs just don't do anything on a flat rear end. They're made to keep airflow attached, but there's nothing to attach to in this case.