Power transmission question

[2strok4fun]

Here is one that I am sure is simple, but I cant find the answer.

If I have a pump that requires 12hp @ 1800 rpm and a motor that produces hp and runs at 3600 rpm with a 2:1 pulley ratio, what HP motor is needed?

do I still need the 12 hp? or will a 6 hp do with the reduction?

Thanx

 

[mideastrider]

If the pump requires 12hp you'll need 12hp for the pump to make its rated output.

 

[rmc_olderthandirt]

Yep, the engine needs to produce 12 Hp at 3600 RPM.

I would recommed a larger motor and throttle it down some.

Rod

 

[MrLuckey]

You gotta admit it would be really cool to do 12hp worth of work and only use 6 hp getting it done :)

 

[2strok4fun]

You gotta admit it would be really cool to do 12hp worth of work and only use 6 hp getting it done :)

Yes, that is my initial thought, but then I started thinking that HP is only a calculation based on torque and if I am running the motor at its torque output at 3600 rpm, does the 2:1 pulley reduction double the torque at the 1800 rpm at the pump less parasitic loss?