Electric Water Pump Options

[Ribfeast]

Running the pump and thermo fans for 5 mins after the ignition is switched off, maybe through a turbo timer, would be the go Reduce heatsoak somewhat.

[bobob]

why not run it on a temprature switch like http://jaycar.com.au/productView.asp...Max=&SUBCATID=

rather than a turbro timer..

[TooF]

yeah youd always run it based off temperature.. no real good reason to run it for a specific time. just like a turbo, if your oil isnt hot no need to idle down.

[Ben Wilson]

The bigger question is how do you turn it on?

If you just hook it up to a temp switch, you've got a great chance for thermal shock when it first turns on...

The Davies Craig controller has a really nice 'soft start' which takes care of that.

[TooF]

edit: sorry i didnt think that thought properly..

you would have it start as you started the enigne straight up no warm up period (the thermostat sill in factory housing would provide that)

and the control off the temperature switch would only be for the shutdown procedure. when the engine was on and running the pump would always be ON. the only time the temperature switch would come into it would be when the engine was off and you were in cool down mode.

[jezza323]

yeah you need to to be run when the engine is running OR the temp is greater than X (thermo switch) and you use the std thermostat to control flow on startup

[Sam_Q]

I can see no way that this can be controlled tempreture wise unless its changed from full speed to a low speed. While this does sound strange theres some logic in what I am saying. I would think that the heat generated in a engine is relatively localised and although the cast iron and aluminium changes that somewhat it still is focused around the upper parts of the cylender bore. Lets say you put the tempreture probe in the water pump inlet or outlet, the bores could be cooking and I think it would take a while for the heat to reach the tempreture probe through the block or head. In other words If theres no water flowing then theres no way for the hot water to reach the sensor.

So I think it might be best to have the pump on a very low speed whenever the ignition is on and a high speed via a tempreture sensor.

Does this sound right?

[TooF]

yeah i dont like the idea of the pump not running at all on start up, hence why in not a huge fan of the DC pump and they way they do their cold start up. thats why ive struck an interest in these procomp pumps. you get the soft start up of the mechanical pump with the temperature controlled by the wax thermostat jsut like a stock mechcanical system then you also get the cool down benefit of the electric.

i have no real concern trying to scavenge the last couple of hp by not running the mechanical pump its just a post shutdown cool off issue.

[jezza323]

i would go with just a standard speed, when the ignition is on, then a temp switch after shutdown (set to a fairly low temp, say 70ish?), until temp drops below the switch, as the pump wont stop you always have coolant flowing past the switch when you need it

[Ben Wilson]

The DC pumps are off when the engine is cold to let the motor warm up easily. Once the temperature starts to come up, they run in 3 second burst at 3v increasing in frequency until they get near operating temperature, once the engine reaches operating temperature the pump runs constantly at 3v which ramps up as the temperature increases.

With my setup, I could start the car in the garage, back out, then get out and close the garage door. By the time I reached the end of my street, the engine was at operating temperature, I never saw the guage move after that...

Luckily, with the mr2, if you got the ignition switch half way between acc and on, the thermo fans turned on along with the pump, so it was easy to cool down nicely.

[Sam_Q]

how can it know the temprature if the water isnt flowing?

[Ben Wilson]

Because there is a temperature probe in the water jacket inside the head.

[Sam_Q]

ok this might sound dumb but how do you get a probe in there? is on on a pigtail set of leads?

[TooF]

the 4age has one from factory at the back of the head.

[Sam_Q]

I know its a bit far fetched but the water jackets around the bores could get hot spots before that tempreture probe would pick up much at all. I stick with what i said at the start: yeah sure its highly unlikely but I want a low volume of water going through there at all times