Getting back to the original question about doubling the impeller speed. Here is the basic relationship that will apply to centrifugal pumps:

Doubling the impeller speed will increase the flow rate by up to a factor of 4 under ideal conditions. It could also require up to 4x the amount of power to drive it as a result, depending upon conditions.

To roughly double the flow volume (at the same head pressure), increase the speed 140 to 150% of stock. Power required to do the work will double as well.

The key here is that the amount of power required to move the coolant is proportional to the weight of coolant that it must move in given time. Notice that I said flow and not pressure. I know this seems counterintuitive, but as an example, increasing the head pressure will reduce flow and thus reduce the amount of power required to pump it.


On the subject of motors:

General purpose DC motors tend to have some wiggle room in them. Keep in mind that it is generally thermal considerations that will usually determine the maximum rating of a motor. In many applications, it is not unusual to adjust the load to bring it within the capacity of a motor. This is done by measuring the current input to the motor (at its rated voltage) while increasing/decreasing the load to achieve its rated current. Additionally, it is not unreasonable to attempt to increase or decrease the voltage to a DC motor (within limits), but you will have to reduce the maximum current to the motor to keep the product of current and voltage constant, or below the max wattage rating.

I don't think you have much to lose if you want to try to adjust your pump's speed and capacity within some reasonable limits.

 

now THAT is how you answer a question!

but what was wrong with the stock water pump in the first place?

 

i need to increase the cooling capacity of the motor. but cannot have the stock mechanical because it takes too much of the needed room in front of the motor.

 

Just doing a little research and thought I'd mention something....

The reason you run an electric pump inline with a machanical pump is because mechanical pumps dont flow worth **** at low rpms. The electric pump flows the same all the time so it picks up the slack of the mech pump at low rpms.

If you reseach some you'll see many companies sell aux elec pumps for cars with large engines like big blocks so that they dont run hot at stop lights ect. Its pretty important for real high compression N/A big blocks and other high performance N/A engines.

I dont think that scenerio would be of much use to us though.

Stephen

 

that's the point i was getting at with the porsche/vdub conversions. that water has to pump through like 15-20 feet of pipe.

 

It is sad to see that more and more posts in this forum are turning into CAT FIGHTS. Come on guys grow up.


Speed of light – You are right on the money – for DC operated motors.

 

That's complete bullshit. I don't know where you get this idea from. Faster flow cools better, if only because it creates more turbulence.