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PWM a electric water pump

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I am looking to install a davies craig EWP130 to replace the mechanical pump on my 3SGTE.

plan would be to use a DPO on my haltech PS1000 to drive a solid state relay. (haltech are so far the only SSR I have found that I would trust.)

I want to set it up as a PWM fan and set the start temp at -40 to -10'c as this will give me a starting duty of about 10% to 40% at 15'c (doesn't get that cold where I am plus its a track mostly car).

my question is what starting PWM % have people found to work well? I wont have a thermostat so to much flow will make warm up slow (not the end of the world) but too slow a flow will lead to nucleate boiling.

so what have people found? any tips? anyone see an issue?

thank you

You should consider using thermostat anyway. it will control coolant temp better, then EWP with PWM %.

I had EWP150 with radiator in the back of the car. Even with Duty cycle at 30% it cooled the car too much.

Had to make remote mount thermostat housing and put there 71C degree thermostat. Now have stable 79-81C all the time, even for 10 laps non stop at 2bar boost.

looking into a thermostat now.

how did you control the pump?

I agree with XtraRacing keep the thermostat. I have an EWP 115 on my Holden V8 in my landcruiser and it definitely warms up better with the thermostat in place. You can get a high flow thermostat for many cars now. I just control the EWP with the Davies Craig controller and it does a good job.

its not really possible to keep the thermostat as it is after where the ewp will be.

im looking at an inline bypass style but I really wanted a simpler system.

maybe adding a swirl pot and header tank will get me similar performance to the EWP set up?

I know Davies Craig initially recommended taking the thermostat out because the pump itself is supposed to act like thermostat but like Xtraracing said without a thermostat your engine will run too cool (most of the time). Even in our hot summer climate (43 degrees C in Broome today) the engine temps will not be consistent.

I fiddled with mine for about a week raising and lowering the temps on the controller in order to find a happy medium. My troopie regularly hauled a float full of feed up and down winding roads and without a thermostat it just wouldn't warm up well but (due to the small frontal area of a 75 series landcruiser) under heavy load it would overheat quickly. Fitting a thermostat fixed both issues because it offered just enough restriction to force the water to stay in the radiator long enough to cool down.

Anyway, my EWP is in the bottom hose, where they should all be because it has to be in a location where water naturally falls to, and my thermostat is in the inlet manifold after the EWP. It works a treat because it circulates the water around the engine more efficiently than just the standard water pump (which I have also kept). When the thermostat opens at 160 degrees F the pump is still only on minimal flow (just enough to move the water through the engine more efficiently). This is where the EWP comes into its own it keeps the water circulating but gives it time in the radiator to cool down properly. Likewise when it is needed and the pump is on the majority of the time the flow of 2 pumps in series is better for keeping the engine temps consistent from front to back. I've never had a flash over heating since I set it up like this.

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