mag pumps

[NVJAY775]

We have less than 14psi to work with until water boils over the tops of the blades. Maintaining positive pressure is very difficult at low speeds. This is why smaller diameter 140 pumps work well on race boats and sitdowns. Larger diameter impellers with flatter blades do noticeably better from 0 to about 15mph. The stock 144 pump is very good with props up to 16 degrees spinning 7000-7200rpm. This is good for over 600 pounds of static thrust and just happens to be where a good stock stroke engine will run. Strokers need a larger pump because they cant turn any faster and adding pitch on a 144 makes them cavitate more until you get moving. A pressure gauge, thrust meter, and tachometer has suggested that the area in front of the prop and pitch of the blades has more important to freestyle performance.

That helps explain a lot to this pump noob. Thanks!

 

[ryan]

the 148 is in a blaster2

 

[norcal ex]

Nothing higher than a 13 on the first number?

it was getting worse at the 13 so i stayed at a 12/17