Didn't know where else to post this...
Were trying to figure out the minimum required hp for a go kart were building but all the calculators want a trap speed which we don't have.... I just was wondering if someone could help me out in anyway....
We have a high gear ratio of :54 and LG 3.38 with 3600 rpm

minimum HP? more is better ofc.

my g'pa built one with a 6 hp lawnmower enigine. it was ok for a 5 year old (slow and much slower with more than 50 pounds) i suggest at least 20 to have fun on a concrete track, maybe more for grass

This post was edited by juliusjuice on Feb 20 2011 03:57pm

a horsepower is 550 foot-pounds per second. So 1 horsepower can move a single pound 1 foot per second. Let's say the go kart weighs 200 pounds and the kid weighs 50. A single horsepower can move the go kart 2.2 feet per second, or 1.5 mph.

If you've got an adult in it, its total weight might be closer to 400 pounds, in which case it could move 1.375 feet per second, or 0.9375 mph. A 20 hp engine, then, will reach a max speed of 18.75 mph.

dont forget drag, inefficiency of the drive train, the size of gear used and any other friction between the engine and the driving surface. i think the cart would weight 300-400 with a 200 lb adult, i would bet that figure is pretty accurate if the math is correct. i read somewhere that the human body can put out about 16hp so the math seems likely as well. better make it 30hp!

boring...

with close to zero info, you will not get any good answers..