Help reaching autocross goals

[rollingworm]

I am entering into a contest that my university is holding this coming May. The contest is an "e-vehicle autocross" this consists of a 30-60 second course with many hard turns and a couple straights (I'm guessing course isn't released until the morning of the race).

I am trying to use a racing kart frame and convert that to electric, while still hoping to be able to swap the motor back in to race it in regular karting events.

So with that out of the way, what would my optimal design be?

 

[Badot]

Having the course so short adds an interesting concept... ideally you'd only use the batteries you'd need to reduce weight, but practicing driving the thing with only a minute's worth of battery onboard would be a pain... and adding more would change the characteristics of the vehicle.

Realistically with high draw low duration a supercapacitor may edge out a battery.

As far as the design itself, seems like you've just about figured it out... replace gas engine with electric motor and batteries.

Maybe you could pull a top gear and couple an electric motor with a gasoline generator.

 

[itsid]

motor limitations ?

if not I'd recommend a diesel truck starter motor or say one off an excavator or something, those can be had for reasonably cheap on a junk yard and still provide TONS of power.
think something around 5-6kw for example, while only running on 24V

that's massive amperages and only very few batteries needed to provide those;
the motor will burn out within a few minutes of continuous use, but 60sec will work well;
so the only drawback will be the controller, which is either expensive to buy (something with up to 400Amps would be needed) or a pretty extensive DIY project.

Anyways, any race has rules, so it'd be important to know what rules apply here
(max motor ratings for example etc.)

And for the swapping.. not that easy I'm afraid,
electric motors do have a very different footprint from gas engines, so if one fits perfectly, the other will not fit at all.
So you need to swap the rear end completely.
for weight distribution you'd want batteries towards the center of the kart (like where the sidepods are)
that subframe must be removed if you want to run a gas engine again... possible, but not optimal.

'sid

 

[rollingworm]

Here are the rules.
Any more suggestions based on these?


https://www.rit.edu/imagine/contests-autox.php

 

[itsid]

cool.. I see no reason why NOT to go for biggest accessible power.
I think you can still beat the (not applied) powerwheels $500 limit with a starter setup.

But keep in mind, that's really for a 1min ride..
after any such power cycle a starter motor needs time to cool down (think in 15min minimum)
otherwise it's likely toasted after run #6

Anyways..
Since I think it'll be a parking lot where the race is being held...
get a race kart frame; find one late 80's early 90's I'd say.. those will most likely not meet FIA rules anymore and are not yet eligible for a true vintage kart race,
so they should be relatively cheap while still being in good condition.
make sure to get a european model with a sunny set up (50mm rear axle / ~2")
and with a working brake.. that'll come in handy when you end up with a large electric motor

Then, make sure bearings and wheels are good (refreshened) to have a braking roller

then check the room you have for the motor, and batteries
(again batteries if they come in bigger numbers are best left and right next to the driver)

And then find a motor.. I'd say 4kw or more should give you plenty of acceleration..
at best try to find a motor and controller from an electric golf cart. just get rid of it's transmission and you'll have a lot of power and reliability

good luck.

'sid