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MAX Update No. 63: What Could Be Better?

No, this is not a rhetorical question. I'm confident I can get MAX back the way it was, but surely this is the perfect opportunity for improvements.


Here's a few I have in mind, clumsily photoshopped onto a photo of MAX. No, this is not a recent photo, Oregonians don't wear shorts in November; we clicked this pic a couple months ago, but I added the computerized imagery today and, as you can see, I've never had a lesson.

From a drag standpoint, MAX still has some low-hanging fruit. Here are five improvements that won't break the bank:

1) I know, I know, intuitively it doesn't make any sense, but we can reduce MAX's drag by adding a spoiler to the stern. Mind you it would be even better to make a whole new stern section, and a spoiler is a way to solve a problem that ideally wouldn't be there in the first place, but car design is a compromise. The Lola which provided MAX's rear fenders was a race car, and it needed to be short enough to snick in front of other race cars, and that's a little too short for optimal streamlining. As far as the wind is concerned, a spoiler can make a car behave like its trunk deck is longer and taller, yet it'll still fit in the same size parking space.

A spoiler for MAX will cost peanuts. A sheet of aluminum with a 2” lip on top and holes for the tail lights and the license plate bolts. It'll be easy to plant a spoiler on the back..

2) A head fairing. MAX is getting slippery enough that little things are starting to matter, such as my head sticking up in the breeze. We can cut that drag in half by streamlining my head from the back. It will also cover the roll hoop, which should probably be there, right? Roll bars pay for themselves with a single using.

I'll make one for the passenger too, though I didn't draw it in yet. As you can see, I was rapidly running out of artistic talent.

3) I'm still torn on the best way to deal with this part of the car. A chin-high bump on the scuttle is enough to deflect the air over the driver — it doesn't even have to be clear since I can see over it — but that bump won't deflect a deer. I wear goggles for eye protection, and they're fine for bugs, but goggles won't stop a deer either. Even a windshield won't stop a deer, unless it's well braced with other structure, and a windshield with a roll cage behind it is the safest way to go, but that will add drag safe is safe enough? Hey, Danger is my middle name, and I have a motorcycle endorsement on my driver's license — I think MAX is safer than a motorcycle and apparently that's good enough for me, though it may not be good enough for you.

4) I think filling in that notch behind the front tires will improve airflow a tad. Tuft testing will tell.

5) Goodyear sent MAX a set of Goodyear Assurance Fuel Max tires, like the ones on the Avion (see MAX Update No. 57) which they say can improve fuel economy by 4%. If so, that's a lot of bang for the buck, and I'm looking forward to testing them.

But first I have to get MAX back on the road. Busy busy busy, work work work.

Photo by Jacky Leggitt 

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jack mccornack
11/29/2010 11:15:04 PM

Thanks for the comments. My 14" wheels are cast aluminum and conventional racing hubcaps won't fit, but I'm looking into substitutes (I wasn't kidding about the pizza pans). As for hypermiling, I want to make the car do the work, not the driver, so no pulse-and-glide or the like. Air dams are very effective on cars with draggy bellies, but with a sufficiently smooth undercarriage I think you're better off without them. At Bonneville Speed Week, modified stock cars run air dams, but the streamliners don't. Full skirts on rear fenders are always going to be a help. Full skirts on front fenders, well, it depends on how wide you want your car and how much you want to steer. Dodici, one man's underpowered is another man's adequate. Which of my ideas are not applicable? (And BTW, I've been an EAAer since the '70s; lots of good information there)

dodici cilindri
11/27/2010 2:12:56 PM

Since we are basically dealing with an underpowered vehicle that has difficulty getting out of it's own way, some of the ideas you presented are not applicable. Prior posts indicate a terminal velocity that may exceed a Piper Cub. However not by much. As such you need to be looking at the reading list of the Experimental Aircraft Association (EAA). I would also suggest the book section from the catalog of Aircraft Spruce. You will also find much worthwhile information concerning both metallic and non metallic body construction means and methods. The end goal of improving the mpg of your land vehicle is not that much removed from the lift/drag ratio of a glider.

11/26/2010 2:41:05 PM

full skirts on the Auto Union V16 type C Streamliner. Like this one.

abbey bend
11/26/2010 12:47:05 PM

Another item to consider, very cheap to build, very effective results, is an air dam under the chin. The ones I have used, I designed to hit the ground at the same time as the suspension bottomed out. I have found using a stiff rubber or lexan piece that moves up and down with the suspension, not very hard to do, this enables it to have a movable piece almost on the ground, keeps more air for under the automobile. Even a stiff rubber bit below the air dam proper, works very well at reducing drag under the car, much better than what a belly pan does. They also have and added benefit, of reducing engine compartment temperatures. I think it is because of increased air movement through the engine bay. I have achieved results of 1 to 3 MPG with a dam and top speed increases of as much as 10 MPH with better stability. Not a big concern for your project I know, but it does show good results when used.

charles j_3
11/22/2010 2:57:07 AM

for hubcaps try these And for driving techniques from a chap who gets 62 miles per gallon from a Ford Escort Zx2 see if you can contact him from here He has all kinds of hypermiling ideas.

jeff dean
11/20/2010 7:01:54 PM

Jack, When you put the new Goodyear Fuel Max tires on (hopefully they are taller), maybe you could scrounge up some light aluminum rims. Reduced rolling weight might help mpg without much work.

jack mccornack
11/19/2010 11:55:38 PM

> does max have a belly pan or one in the future? MAX does, it's pretty well covered, I can do a bit more. I'll show pix on another Update. > Skirts covering the wheels might help On the rear wheels yes, the fronts have the problem of needing space for the wheels to steer, or... > Maybe just moony hubcaps. ...I've been looking at pizza pans. Champagne living on a beer budget (or at least a beer and pizza budget).

jeff dean
11/18/2010 8:35:15 PM

Jack, Its me again, does max have a belly pan or one in the future? Skirts covering the wheels might help, but wouldn't do much for styling. Maybe you could start a new trend. Maybe just moony hubcaps.