bb2 surge pump

[pierre]

i have a 2hp motor 3450 rpms what size pulley do i need on the motor with a 12"on the pump

[Dennis H.]

Not sure if will be able to make the motor work for you.
The bb2's or for that matter piston pumps like to run below 500 rpms but the sweet spot is about 480rpm
To get the pump pulley to spin at 480 rpm you will need a motor pulley of something like 7/8"!
With motor rpm of 3450 you need a combination of pulleys ro give you a 7:1 drive ratio.

Pump pulley of 12" = 18.84" circumference. 18.84/7=2.69 od for the motor pulley. Which gives you a motor pulled sze of .857".
That motor shaft size is probably a 3/4".

[Bucket Head]

Take the pump speed (Surge shows 475 as the higher rpm on an SP11 pump) divided by engine speed. That equals the reduction. Take the pump pulley diameter and multiply it by the reduction. That equals the engine/motor pulley diameter. My figuring shows a 1.65" diameter pulley, which is pretty close to a 1.75 (1 3/4") pulley. Maybe an industrial supply can get a 1.65. I would shoot for, if possible, a 1 1/2" diameter pulley. That would put you at about 425 rpm's on the pump, which will be a little easier on it. Remember speed eqauls more heat, and both are bad for these old piston pumps. With low rpm's, cool operating temperatures and good (changed often) oil, they will run forever.

Steve