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eodjohnson

  • Karma: +0/-0
hp vs trq selecting impellers
« on: October 21, 2010, 07:58:07 PM »
i come from car world and torque gets me places but when i see the impeller charts they are all hp vs rpm vs impeller size

is torque not as important as hp in a jet pump?
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go all out or stay at home!

GT Jets

  • Karma: +192/-0
Re: hp vs trq selecting impellers
« Reply #1 on: October 21, 2010, 08:13:01 PM »
i come from car world and torque gets me places but when i see the impeller charts they are all hp vs rpm vs impeller size

is torque not as important as hp in a jet pump?

This could easily turn into a crazy long thread, so here is the first of many two cents... ;D

First I will be quoted as saying; "torque is king in a jet boat"...There, I said it. :sly:

A jet pump absorbs horsepower, but the "peak" horsepower need to be at a substantially lower rpm than in that of a prop boat.

So that being said, low end (low RPM torque) is absolutely useless, the pumps do very little work at a low RPM, so the torque required to get up to and passed about 3000 RPM is extremely low. The torque is required after that point though, and a lot of it, so I call it safe to say that your peak HP should occur at a low RPM and the torque curve should peak at the highest possible RPM and still make good HP..

Really, it is a balancing act between the two.

I think when most people think of a torque monster, they think of something like a stump pulling truck, there are more ways than one of making major twisting power.

I guess another way of stating would be; long stroke, big exhaust, hot ignition and decent compression....

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

eodjohnson

  • Karma: +0/-0
Re: hp vs trq selecting impellers
« Reply #2 on: October 24, 2010, 01:22:11 PM »
ok good so it does have a say i feel better now. 
from looking at all the charts i got the impression it wasnt usefull information
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jet boat performance

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Re: hp vs trq selecting impellers
« Reply #3 on: October 31, 2010, 09:27:03 AM »
ok good so it does have a say i feel better now. 
from looking at all the charts i got the impression it wasnt usefull information

Where your projected motor make power how bigs the boat and what are you doing with it ?
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