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Fasttrack
10-05-2005, 06:52 PM
Anyone got some great ideas on how to build a high mileage go-kart for the SAE competitoin? Any veterans here who could share some tips?

madman
10-06-2005, 02:00 AM
We sponsored a local university for a autocross type race car. It made noise layed rubber and was wacky looking but fun. Is youre project for gas fuel mileage .

3 Phase Lightbulb
10-06-2005, 12:26 PM
Make a pedal powered go-kart and hire Lance Armstrong to drive it in the competition.

Ian B
10-07-2005, 09:03 AM
Have a look at:
http://www.bath.ac.uk/mech-eng/ecomarathon/ecocar1/

and

http://www.bath.ac.uk/mech-eng/ecomarathon/ecocar2/

Search on "Shell mileage competition; lots of hits...

hth,

Ian

madman
10-07-2005, 11:09 AM
Wear really baggy trousers. Underneath have hidden a bunch of small yet powerful rodents. A small hamster wheel linked to the transmission and cleverly disguised as a directional aid. Slip rodents inside and let em run. If they slow down poke em in the ass with a sharp pointy stick. Good Luck Dont get caught.

Evan
10-07-2005, 11:25 AM
Machine a small cavity in the engine somewhere to hold an ounce or two of nitromethane...

jburstein
10-07-2005, 12:03 PM
pay mucho attention to aerodynamics. This means your driver should probably be lying down head first (if that's allowed, I don't remember), so that the body of your can taper down to a point at the back. Make it light--composite structures are good, especially since it's relatively easy to make aerodynamic shapes with them.

Chain drives are more efficient that gear drives. Also pay attention to your gearing, so that you're running the engine in it's most efficient range. A continously variable transmission would be a great thing.

Bike wheels are probably a good choice, especially if you inflate them a lot. You should probably only have three wheels--less rolling and air resistance that way, and drive only one wheel, that way you can avoid having a differential.

Those are some basics. I'll probably think of more, and sorry if you know all that stuff already--that's just the stuff that came to mind (we considered entering super-mileage, but are doing FSAE instead).

-Justin

Your Old Dog
10-07-2005, 09:09 PM
Try not to over steer, you bleed off energy everytime you correct with the wheel.

Obviously a smooth surface with a good wax job on the finish.

Hard tires would roll easier then inflatable.

Black is the fastest of all colors for a paint job. If you're not afraid of terminal velocity paint a number 3 on it large and proud.

Don't put an "On Star" system in it. The antenna will cost you in coefficiant of drag.

Enclose the undercarriage.

Don't put brakes on it. (Actually you'll feel like you are going faster than you are without brakes)

If memory serves me correctly, shape the front like a sphere and the rear like a half to a point so that it looks like a falling droplet. Recent aerodynamic revelations indicate that our thoughts on aerodynamics are actually 180 degrees backward from reality. Maybe someone else can confirm if I have it right or wrong. I heard of this research about 2 years ago.

good luck, post pictures !!

instrkdj
10-07-2005, 11:26 PM
Hello,

When I was in grad school, we built a high mileage car for SAE, with an aluminum frame, cycle wheels, and the body was shrink wrap over an aluminum skeleton. The engine platform was specified by ASE and was a 5hp Briggs/Straton with any modifications allowed. We converted to OHC by using the head from a 50 or 70cc Honda and used an external chain to drive the cam. Beyond that, I don't remember, as it was about 25 years ago (my wife says I have a good memory, too bad it's so short).

Good luck!

Instrkdj

SJorgensen
10-08-2005, 12:27 AM
Put a V8 Mercedes diesel engine in it. I hear they are getting up to 60 MPG now.

dneufell
10-08-2005, 03:22 AM
My high milage vehicle!

http://i167.photobucket.com/albums/u141/dneufell/Freeway/right.jpg






http://neufellmachining.com

Fasttrack
10-09-2005, 01:09 PM
Thanks for all the suggestions! I like the nitromethane idea! We have been using three wheeled frames with shrink wrap over a conduit skeleton. I wish we had aluminum but all of our material has been donated by a student and all we got was steel. Not that i am complaining with steel prices being what they are. http://bbs.homeshopmachinist.net//smile.gif
Our major downfall i think is the inability to coast; all the other teams shut off thier engines and coast down to about ten miles an hour before they start back up.

tryp
10-09-2005, 08:18 PM
No coasting means you have drivetrain friction. Make sure your tires are rock hard, overinflated a few psi. You have good bearings (oil bath would be nice as opposed to greased)and perhaps most important make sure you have a one way clutch somewhere in the drive system so the engine isn't slowing you down when you coast.

Also get rid of the steel if you can swing the cost.

Fasttrack
10-13-2005, 07:12 PM
We tap the race out of the bearing, clean 'em, spray a little wd-40 in there and reassemble. Pretty drastic results; talked to a guy in the go-kart racing field and he said they've been doing that for a long time. Not that great for wear though! We have a centrifugal clutch so it can coast, only we have no way of shutting off the engine and since the clutch acts as the one way freestyle, the any resistance there is multiplied by the ratio between the two sprockets...

darryl
10-14-2005, 01:05 AM
Has anyone studied the effect of suspension on fuel mileage? I suspect that eliminating any energy absorbing areas, like shocks, will increase efficiency. Tires are the first shock absorbers, get rid of them. Somehow.

jburstein
10-14-2005, 02:12 AM
Actually suspension helps in most cases. Without suspension when you hit a bump, a lot of that force goes into slowing you down. Besides which it is very uncomfortable, so you do want some suspension travel, it doesn't have to be more than an inch or two, but you need that much.

-Justin

darryl
10-14-2005, 03:33 AM
I agree you need suspension. My thinking is that it should be very compliant, without energy absorbing mechanisms. The tires should be quite hard, and the wheels and hubs as light as possible to minimize energy being transferred into the body.

What are we really talking about here- a driveable get-around vehicle, or a super milage contest winner?

Norman Atkinson
10-14-2005, 06:45 AM
SJ! A joke abot the three pointed star?

My wife returned 53mpg( uk gals) on recent trip. This was toting a C Class 270 CDI Estate body shell.

These somewhat snide remarks are falling flatter and flatter. The cars of non- USA- be they European or Japanese are now doing surprisingly high fuel economies.

Only one Wednesday night last, I was discussing a new CLK petrol 200 with its owner. It was only doing 31 but it was petrol and not diesel.

I said sometime back that it was only money.
Might I be more (im)pertinent- and add Yours?

As I keep saying " The German and Austrian Road sweepers can't be wrong with their Mercs" For my part, I also have a sneaky little Skoda 2cyl 1.2 Fabia. MPG?- I wouldn't like to really rub it in.
I've even got a 903cc Seat Marbella that is 11 years old. Fiat engine- great little thing- cost?- well the Spanish Government gave me £500 towards buying it. Street cred- zero- but my bank manager and stock broker love it.

Norm.

glenj
10-14-2005, 09:56 AM
Check these guys out. They are riding pedal powered machines to over 70mph.

http://www.wisil.recumbents.com/wisil/whpsc2005/resultsfriday.htm

If you built a 3 wheeled version with the engine in back you'd be off to a good start. You might even be able to add gearing straight out of a bike if you could let off the gas a little to shift. Modern high end gearing allows you to shift under pedal loads quite reliably.