EWP on Supercharged Atom

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Hi,

Does anyone know the details of how the electronic water pump is wired / works normally? I thought mine was possibly broken as I could never hear it operate but it only comes on with the radiator fan which struck me as a odd but I’m no expert.

From what I’ve read of the EWP it’s usually thermostatically (hence the fan operation?) controlled or can be used to replace a regular water pump with the engine block thermostat bypassed. I wondered if this could be powered manually to help push air out of the cooling system or run continuously to help keep the temps down, anyone tried that?

Cheers!

[John Scherrer]

As I recall, the electric water pump is part of the supercharger option kit.

It is in addition to the stock mechanical water pump and I think only kicks in when the electric radiator fan is called and also continues to run for a time on engine shutdown when of course the mechanical pump isn’t working.

This is to avoid any local water boiling that would lead to an air lock and creating damaging hot spots.

After a heated drive, you can stop with fan going. If you stop the engine by switching the ignition off, the fan cuts too. If you just turn the ignition on again, the fan will restart and cutoff when the radiator water has cooled. Don’t leave the car and forget to switch the ignition off though !

I’m not suggesting that you should do this, it may just be better than leaving the engine idling until the fan cuts out.

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Hi John,

Thanks for the details - you described exactly what mine does after a spirited drive, though the fan doesn't run for very long after the engine has stopped with just the ignition on. It can get pretty hot here (40's) in summer so I was thinking of trying to extend the run time a little, though that could also be a problem given the small battery.

I imagine the pump is operated by the same relay as the fan motor? - oddly I think the owners manual lists the horn and EWP on the same fuse, but I'm not sure how that works?!

Cheers!

[John Scherrer]

I’m not sure about the wiring itself but don’t worry about the horn and EWP sharing the same fuse. (If that is the case)

That doesn’t mean their operation is logically linked, just that they share the same power feed.

The factory have an additional hot country radiator option to manage conditions that you see and that may be the solution.

[autobackup]

John

The 'hot country' radiator is an interesting beast with an added horizontal radiator which really, due to airflow angle, is not particularly effective/efficient.

When my Atom was rebuilt as a 3.5R I had a long discussion with Steve Rooke and, as I have it in Cyprus where it gets REALLY hot, Steve recommended that a much better option would be to retrofit the Atom V8 radiator which decision has been vindicated as I have had no overheating issues during the past 2 years in temperatures that have sometimes been over 40°C!!

[John Scherrer]

Yes, that’s good to know .. probably saves a few pounds in weight and less complex in that there’s fewer parts and connectors/pipes to leak!

Fitting an oil cooler would help too.

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[mention]autobackup[/mention] I’ve now gone a similar route with an upgraded radiator and high cfm fan. I was just curious about the ewp, wasn’t sure if that could also be run to keep the temps down when it gets really hot as an added measure....needless to say it’s not an issue at the moment and I can’t test my new setup (yet).

I’ll see how it goes in the summer all being well, last year on a few occasions the car was really struggling with the heat so I wanted to see what others did etc. My atom is also a pretty standard 3/300, I imagine there is more going on with the 3.5R due to all the other performance bits too.

Cheers!