[Woodsmith]

Interesting thing on the dyno result is that at 50mph it requires 11.7hp to overcome rolling resistance.

 

[Woodsmith]

that is what I mean... Do I absolutely need a peak 120hp motor? when 50mph = 11.7hp?

to travel at 50mph I would need a nominal 8728Watts of power to push around the vehicle...

Im sooo confused

No you don't need 120bhp.

At 50mph you would have 11.7hp in rolling resistance plus a bit in aero drag, you could say the same again, depending on how 'slippery' the car is.

You may only need a motor with 15kW nominal 1 hour rating and it will probably give you a bit more for overtaking that lorry on an up hill run for a few seconds, depending on your batteries and controller.

 

[Woodsmith]

It's called evdrivepower.xls
Hope that helps

Here's a link.

It is very similar to my own simpler spread sheet but I don't have acceleration or gradient and I only calculate for each speed I enter.