How much water does a outboard use?

dont forget the pump becomes centrifugal at high rpm, load drops

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Originally Posted by powerabout

dont forget the pump becomes centrifugal at high rpm, load drops

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1/2 or 3/4 inch water tube in the equation also will effect the amount.

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Originally Posted by phillnjack

Its a very valid and good question, as I like a few others have often though about an external electrical water pump to feed the motors.
one way to find out would be to put a drill on a drive shaft and see just how quick you empty a certain amount of water in say 3 minutes. BUT you have to remember its not the amount a motor actually uses, the adaptor chucks out any excess water that the motor dont need and dumps that into the mid section..... so what the motor consumes will be very different to how much the water pump pushes out... I would think you dump out more than you consume by a long way..

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Let me know when ya find a drill that will spin 6-7 k

I'm going with yes.

Roughly 4 gallons a minute at 30psi from a 1/2 tube

just put an attachment on a angle grinder, can then spin upto a lot more than 7 grand then..

and that would make the pump even more efficient.

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Originally Posted by phillnjack

and that would make the pump even more efficient.

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But your angle grinder does not have the power to move that much water? what ya gona do take a generator on your boat to power the grinder or one hella long cord from your house outlet.:leaving:

water psi formula is velocity squared times .0142, once past say 25 mph the impeller is the restriction.

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Originally Posted by Whaaaaat

I think once your up to speed, especially the speeds some of us see. The water pump is actually limiting flow. If it wasn't for idle time I doubt a water pump would be necessary. Someone better at math than me should be able to get close just by knowing the inlet area × pressure.
Pressure would be a factor of speed. That should give an idea of how much water your passing, how much you actually need, would get a lot more complicated

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I’ve often wondered if at speed on say a sporty of there was no pump would water actually go into the pickups or just pass them. I think the suction from the pump might be pulling water into the pickups at high speed.

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Originally Posted by racervboat

Sorry killer I just could not resist. How much wood could a wood chuck chuck if a wood chuck could chuck wood.:D

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Why is a cow??

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Originally Posted by 90 5.0

I’ve often wondered if at speed on say a sporty of there was no pump would water actually go into the pickups or just pass them. I think the suction from the pump might be pulling water into the pickups at high speed.

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no, a lwp can over pressure the system so you could run without an impeller but no stopping..

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Originally Posted by 90 5.0

I’ve often wondered if at speed on say a sporty of there was no pump would water actually go into the pickups or just pass them. I think the suction from the pump might be pulling water into the pickups at high speed.

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The water pump is if anything a restriction. It has no suction beyond low speed.

Put on a test wheel and put the motor in a tank and see what the pump doesn't do at higher rpm.

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Originally Posted by FMP

Put on a test wheel and put the motor in a tank and see what the pump doesn't do at higher rpm.

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How often you go cruising with your test wheel? What kind of numbers you put up with that thing?