Configuring a secondary electric water pump?

[R1 Indy]

Basically I want to install a electric water pump to assist the mechanical water pump, but on a switch as only really needed for trackdays.

The car is an MK Indy R with a 2008 R1 motor. This is the one that overheats by cyl 2&3, hence the extra cooling.

I've bought a Davies Craig water pump, the 80L/m one.

Now I understand I need to install this between the bottom rad hose and engine.

The bit I'm unsure of is as I'm just running it off a switch, what I do with thermostat etc..

The instructions say if running constantly I need to remove thermostat or drill a hole in it and disable mechanical pump.

Or if run off a temp switch, then keep the thermostat and mech pump.

So am I right if I only turn it on once up to temp, I can keep thermostat and mech. Pump? Or should I put a small hole in thermostat?

What would happen if I turned it on and thermostat wasn't open?

Can anyone advice me what's best here?

Cheers

[greengreenwood7]

at the risk of being a numpty i'm intrigued by this, because surely the elec pump will be hampered by the mechanical one ( or vice versa).....i'd have thought that in a closed loop system of any type unless 2 pumps are equally matched 1 will restrict the other?

FWIW i have a Davies/Craig elec pump and no mechanical pump, works very effectively on a zetec. When i bought the car the prev owner hadnt fitted the controller and it ran continually - and therefore the temps were a bit low. Since fitting the controller its bang on and is now set to also run after the engine is turned off so to bring the final temp down a bit.

[gtmdriver]

I ran one of these in my GTM Coupe as the Mini engine is in the rear and the rad is at the front so it's a long way for the A series pump to push the water. It is only an impeller after all.

I was also loading the cooling system even more by using a Laminova oil/water intercooler.

It made a tremendous difference to the cooling efficiency and the oil temperatures.

It fits in the return hose from the radiator where the water is cooler.

If you have the electric pump running all the time it will obviously be trying to pump water when the engine is cold and the thermostat is shut. This will damage the pump. This is why you have to remove the stat if you hard wire the pump.

I wired mine using a thermostatic switch so it only came on when the temperature rose to a pre-set level and the thermostat was wide open. Under these circumstances the Davies Craig pump simply assists the standard pump.

If you wire yours to a manual switch and only use it when the engine is hot you can leave the thermostat and mechanical pump in place BUT you must never have the pump running when the engine is cold and the thermostat is shut or you will damage it.

[Noble P4]

We run a Rover V8 in a mid engine kit car with no through flow of air. Fitted Davis Craig pump with stat switch and did away with mech pump and thermostat. Never overheated or caused any probs in 18 months of road use.