How many GPM from the water pump?

[Topless]

Originally Posted by itsnotanova

I'm looking at going to an electric water pump on my rallycross boxster. Anyone know how many gallons per minute the factory water pump puts out?

This is an interesting question and not as simple as it seems. The stock WP is belt driven continuously variable based on rpm. It flows twice the gpm at 6k rpm as it does at 3k rpm, less head losses. Electric pumps also vary in gpm a lot based on head loss. You need to match the electric pump flow to the OEM pump through the system to get it right.

You could run an experiment. Do some math and figure out the actual pump rpm while the motor is turning at 6k. Then rig a drill to drive the pump, run water from one 5 gal bucket through the pump > through the plumbing and radiators, back to the motor, and into a second 5 gal bucket. Fire up the drill to simulate the engine at 6k and time the process to fill bucket #2. This would reveal the max flow needed from an electric pump.

Hook up your chosen pump and test it to make sure it meets or exceeds your minimum required gpm through the system. Allow your t-stat to regulate engine temp by opening and closing as needed to keep coolant at 180F-220F.

I don't know anyone who has measured this on a Boxster but it would be very useful in a racing application. The drag racing guys have been doing this for years on V8s.
https://www.chevyhardcore.com/tech-stories/fuel-cooling-ignition-tech/tech-feature-what-you-should-know-about-electric-water-pumps/

[JayG]

Originally Posted by Topless

This is an interesting question and not as simple as it seems. The stock WP is belt driven continuously variable based on rpm. It flows twice the gpm at 6k rpm as it does at 3k rpm, less head losses. Electric pumps also vary in gpm a lot based on head loss. You need to match the electric pump flow to the OEM pump through the system to get it right.

You could run an experiment. Do some math and figure out the actual pump rpm while the motor is turning at 6k. Then rig a drill to drive the pump, run water from one 5 gal bucket through the pump > through the plumbing and radiators, back to the motor, and into a second 5 gal bucket. Fire up the drill to simulate the engine at 6k and time the process to fill bucket #2. This would reveal the max flow needed from an electric pump.

Hook up your chosen pump and test it to make sure it meets or exceeds your minimum required gpm through the system. Allow your t-stat to regulate engine temp by opening and closing as needed to keep coolant at 180F-220F.

I don't know anyone who has measured this on a Boxster but it would be very useful in a racing application. The drag racing guys have been doing this for years on V8s.
https://www.chevyhardcore.com/tech-stories/fuel-cooling-ignition-tech/tech-feature-what-you-should-know-about-electric-water-pumps/

Great idea!

Only problem I see is finding a drill that will go to 6k rpm.
A dremel will, but probubly doesnt have the power to spin the WP
Might need to rig up a motor and pullys to get to that rpm

[Topless]

Originally Posted by JayG

Great idea!

Only problem I see is finding a drill that will go to 6k rpm.
A dremel will, but probubly doesnt have the power to spin the WP
Might need to rig up a motor and pullys to get to that rpm

Because it is belt driven and runs on different size pulleys I don't think the OEM WP runs anywhere near 6k rpm. With a little math and knowing the pulley diameters you could calculate the equivalent WP RPM at 6K RPM motor crankshaft speed. A pulley rig could also be used to gear your drill to the necessary speeds.

Without doing any of this you could probably just use a 12VDC external pump designed for V8 engines and get close enough... maybe 20-40gpm. I like this idea a lot. With a 12V WP and a 12V PS pump you would remove a lot of parasitic drag from the motor and get better steering, better cooling, and higher reliability. Probably 15-20 HP at higher RPM.

[stephen wilson]

How about an electric water pump with a stand-alone controller that varies pump speed in response to cooling needs ?
https://daviescraig.com/?gclid=EAIaIQobChMIu4SqyMGe4wIVCLbICh0toQcpEAAYASA AEgJk0fD_BwE

[itsnotanova]

Originally Posted by stephen wilson

How about an electric water pump with a stand-alone controller that varies pump speed in response to cooling needs ?
https://daviescraig.com/?gclid=EAIaIQobChMIu4SqyMGe4wIVCLbICh0toQcpEAAYASA AEgJk0fD_BwE

That's pretty much what I was thinking but on a cheaper scale. I like DC water pumps, but I was thinking of using a generic rotary switch. I would control the flow myself by keeping an eye on the temp gauge.

[itsnotanova]

In case someone is searching about electric water pump and comes across this thread. I've successfully installed one and you can see the install here. 6 months to live build thread