Having rear big tires on go kart
- Thread starter JH Pinoy
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Thats correct. You could have so little torque though that you will never get moving. Depends on the wheel size
To figure out how much power you will lose and speed you will gain, divide the radius of the tire by the radius of your rear sprocket. Take this and multiply it by your gear ratio. This is your effective gear ratio putting power to the road.
So, if you have a 15" tire with a 7.5" sprocket (just for example), and your gear ratio is 6:1, your effective gear ratio will be 3:1 when putting rubber to road. So, if you engine puts out 10 ft*lbs of torque and the above, you will be putting 30ft*lbs of torque to the road.
One ft*lbs is the force of gravity acting on a one pound object and is 32ft/s^2 of acceleration. You take your torque and divide it by your total weight then multiply by 32. This will tell you your acceleration.
So in the above example with 30ft*lbs of torque. If the total kart weight is say, 300 lbs, this will give us .1 foot, times by 32, and you get 3.2 feet per second.
So, with the above configuration, you will be going 3.2 fps faster each second until you reach maximum speed.
I THINK that what I have stated here is correct. So, in 10 seconds of time, you will be going 32fps, or 21mph.
The only part I am unsure of is calculating acceleration from ft*lbs, I've only ever used Newtons.
So, if you have a 15" tire with a 7.5" sprocket (just for example), and your gear ratio is 6:1, your effective gear ratio will be 3:1 when putting rubber to road. So, if you engine puts out 10 ft*lbs of torque and the above, you will be putting 30ft*lbs of torque to the road.
One ft*lbs is the force of gravity acting on a one pound object and is 32ft/s^2 of acceleration. You take your torque and divide it by your total weight then multiply by 32. This will tell you your acceleration.
So in the above example with 30ft*lbs of torque. If the total kart weight is say, 300 lbs, this will give us .1 foot, times by 32, and you get 3.2 feet per second.
So, with the above configuration, you will be going 3.2 fps faster each second until you reach maximum speed.
I THINK that what I have stated here is correct. So, in 10 seconds of time, you will be going 32fps, or 21mph.
The only part I am unsure of is calculating acceleration from ft*lbs, I've only ever used Newtons.
Upon looking it up, 1 ft*lbs is equal to 4.44822162 newtons. 300 pounds is equal to 136kg.
Force = Mass / Acceleration, so Acceleration = Mass / Force.
A = 136 / 133
A = 1.02 m/s^2
So, in one second of acceleration, you will be traveling at a rate of 1.02m/s. In ten seconds, you will be going 10.2m/s, or 22 MPH.
Force = Mass / Acceleration, so Acceleration = Mass / Force.
A = 136 / 133
A = 1.02 m/s^2
So, in one second of acceleration, you will be traveling at a rate of 1.02m/s. In ten seconds, you will be going 10.2m/s, or 22 MPH.
/\/\/\/\/\ WOW, good answer!!
This is why I hate engines being rated by horse power and not torque. Torque is far more important than horse power.
Horse power is simply how fast your engine can put out power.
HP = (Torque (in ft*lbs) X RPM) / 5250.
So, you see you can have a large horse power rating but have a very small torque rating by simply making your engine rev really high. You can use such an engine, but you will have to step the gearing up quite a bit in order to translate the high rpm's into power at the wheels.
Horse power is simply how fast your engine can put out power.
HP = (Torque (in ft*lbs) X RPM) / 5250.
So, you see you can have a large horse power rating but have a very small torque rating by simply making your engine rev really high. You can use such an engine, but you will have to step the gearing up quite a bit in order to translate the high rpm's into power at the wheels.
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