Electric water pumps re-visited

[Sam_Q]

revisiting a simular thread a while back I would like to drive my current water pump on my 20v engine with a small belt and an electric motor instead.

much like this:







I would like to know what sort of motor people think I may beed that would provide enough power. I am thinking a thermofan or heater fan motor should do the trick.

[Cuts]

i know this is not anwsering the question you have asked but have you considered a davis craig electric water pump?

[Sam_Q]

no I don't mind the question. I did but I want something that can work properly that over-rated thing can't

I want to keep a thermostat in the system and have something simple piping wise so this seems to be the best bet.

[Cuts]

there is the electronic controller to go with the water pump, that works similar to a thermostat i suppose you could say, as it only comes on when a certian temp is reached.

[Duk]

The most obvious questions are: How much power does it take to run the pump at an effective rate of flow?
And what is the best pump speed range?

*Clever people who have had more sleep than me could have even better and/or relevant questions too

2 motors spring to mind. Either an interior fan motor or a decent size radiator fan motor.

[CrUZida]

I seriously doubt a heater fan motor will have the torque to turn a water pump.
You can usually stop those with your fingers.

Have a look atthe peak current the Davies Craig pumps draw, and look for a motor that draws at least that much.

btw, can you link us to the other thread where you made this decision, just seems kinda backwards to me?

[Tweak]

that pic you have would be for a drag setup. Its designed to run for maybe 5mins max.
Id say once the heat soaked into the plastic motor it would begin to slow down.
Id go a craig davis pump its a proven fact that it works and works well
Also either way you can put a warning light on the dash hooked into the pumps circuit so you can tell if its failed

[Duk]

I seriously doubt a heater fan motor will have the torque to turn a water pump.
You can usually stop those with your fingers.

Probably right about the heater fan motor, but some of the big single fans used in late model car, and some of the grunty aftermarket fans, can draw over 30AMPS.

http://autospeed.com/cms/A_111234/article.html

[Radar]

Davies craig EWP is the shiz... Flows stacks, doesn't draw heaps of power, and best of all helps SHITE loads in the top end..

[beerhead]

I'm not too sure about those Davies Craig EWP's. A mechanic I know has tried using them in the past and was never happy with how they cooled the motor. He thinks the pump physically works well, but doesn't like how the control module mimics a thermostat (or fails to mimic). I'd say over the years it would have become more refined, but I still haven't seen too many people run with them, just sell them 6 months later.

Anyone here had some experience of the later model gear?

I think on a revvy car it might be benificial to use an auxillary and a RPM change over point to turn off your alternator too. But I suppose the golden rule is 1hp per 100amps, so 1% hp gain on a 20V tops...

[Billzilla]

The latest DC EWP is a good thing, but like the earlier models you have to keep it cool and isolated from vibration.
There was a team from the UK (TVR I think) that used them at the Le Mans 24 Hour race on their six litre V12 engine.

[knightrous]

Ford AU Falcon thermo fan motors would be suitable, they are based on the old Bosch GPB fan motor used in a fleet of EV bikes (The motor was tagged EV Warrior). Were used successfully on 12v & 24v in the combat robot community for years.

If you've got a but of money to spend, a brushless motor setup could be done with significant weight reduction and a much more compact package.

[river]

Hi,

Maybe a tad OT, but seeing we're discussing electric water pumps, it may as well go here for discussion......

What benefit do you get out of an electric pump? The conservation of energy still applies, so if you are chewing (for example) 250watts of power for an electric pump, then this must be supplied by the alternator, so there is that load... probably a little more because of inefficiences. The engine drives the alternator, and the extra load the alternator has to put out for the electric pump, would ultimately come from the engine.

I can understand electric thermo fans, because they switch off and on as required, as opposed to having the engine driven fan, or even the hub with viscous coupling, running all the time.

Maybe the electric pump gets its savings in overall power consumption if it also cycles on and off, as opposed to the continually engine driven water pump? Or are these electric pumps variable in speed?

seeyuzz
river

[timbosaurus]

Couple of reasons Mate.

1) water flow doesn't need to be proportional to engine RPM. ie: an idling motor at standstill should need nearly the same flow as a revving engine at high speed.

2) At high rpm the standard pump takes power to run regardless whether it's needed or not. An electric pump only takes power if it's needed. A bit like Alternators that only charge during deceleration.

3) High RPM could cause cavitation on a standard pump.

edit: I wrote that reply in a hurry. Basically what i'm saying is, the power taken out by the pump is somewhat proportional to impeller RPM. The faster the engine runs, the more power the pump takes from the accessories belt. Often when racing etc, the water pump does not need to spin as fast as the engine is making it, so it can be slowed down with an EWP to save a bit of power. In my opinion though, this power saving would be 2/5's of F-All in the scheme of things, and the other things, like water cavitation and pump durability at high RPM are more important.

[Sam_Q]

there is the electronic controller to go with the water pump, that works similar to a thermostat i suppose you could say, as it only comes on when a certian temp is reached.

yeah well someone on this board had one of those and the engine always ran cool, in the end even the tech support guy from Davies craig said to run a normal thermostat, so what a load of shit