The joys of sitting on a train crowded with school kids...
I went back looking at coolant stuff and Electric water pumps and came across this thread again.
http://m.miataturbo.net/showthread.php?t=35609&page=5 This time I actually read it to the end rather then give up in the bickering stage and got some really useful information.
I had already purchased a Davies Craig ewp when I did the head build but got impatient about getting the car back on the road after 12 months of not being mobile.
I also wasn't happy I had answered the questions of thermostat vs no thermostat to my satisfaction and was not happy with how I was going to control the pump. I had a DAvies Craig controller but that would have meant 4 temp sensors! (Ecu, DC controller, dash gauge and after market gauge)
Readers digest of the thread is
- he uses a civic radiator (had missed that the first time around)
- water flowing to fast to cool an engine is a myth.
- Faster flowing water has better heat transfer, makes more loops for time unit so total cooling is better, reduces temperature gradients in the engine and reduces the ability for steam pockets to build
- most ewp are rated for virtually no flow restriction at the publish flow amount for example 80L/min
- thermostats are a large flow restrictor so if you keep the thermostat with an ewp make sure it can flow sufficient fluid at a reasonable pressure restriction.
- using an electronic controller is required if no thermostat. This is arguably a better situation and flow is increased by the lack of restriction.
- a thermostat acts as a restriction which increases the pressure in the cylinder head (normal flow direction) and can help prevent localised boiling. It was argued this an be combatted by increasing total system pressure (radiator cap) or using a higher boiling point fluid.
- reverse coolant flow can lower cylinder head temperatures which is beneficial for increasing power.
- there is a ewp manufacturer which supplies for BMW that makes an ewp with a control circuit built in that allows control with a low current PWM input. I believe the DC pump is only voltage control which makes it hard to control via ECU.
