Pump Theory Queestion

[IDoSeaDoo]

Somewhere I remember reading that the 140mm pump is at it's max efficiency with the 110hp engine. That adding more power (from say a 155hp 4tec or higher) and a taller pitch prop will not yield any performance improvement (in speed, acceleration, or fuel economy).

1. Is this true?

2. What if I were to use the 1995 pump wedge and a longer prop (increase pump volume)?

3. If there are gains to be had, what's the most power I could put to a 140mm pump?

Thanks!

 

[Coastiejoe]

Even if this is the case, an impeller change would get the extra performance from the increased HP.

 

[Dr Honda]

Its hard to say.


First... a longer impeller wont increase pump volume. It will only "stuff" the pump better, and allow for higher pressures.

Second... if you put more HP on the little pump... it will be fine. (within reason) You can open the bowl section to allow more flow, and then add more pitch to properly load the engine. But as we all know... a larger diameter is the best way to handle HP.