I've ran a Davis Craig electric pump and speed controller since putting the car on the road 13,000 miles ago. No mechanical pump at all. No mechanical thermostat.
The voltage suplied to the pump varies based on coolant temperature as read by a thermister installed where the thermostat used to be.
BEWARE of the warm-up curve the Davis Craig controller supplies. It pulses the pump on and off as the engine warms up....off a lot longer than on.
The "curve" it supplies is probably okay for a front engined car, but in a mid engined car, at least mine, the distance from the engine to the radiator causes the radiator to be temperature shocked causing the tubes to crack from the tank. Ron Davis commented that the aluminum radiator can not stand the rapid differential temperature.
I had 2 radiators crack before discovering what what was going on.
The short term fix is to not let the pump cycle on and off during warm up. I keep a constant 3 volts on the pump at all times and let the DC controller ramp it up from there as needed by cooling demand. Warm up times are increased, but I haven't cracked a radiator since allowing it to warm up along with the engine. I am currently working on an upgraded program for the DC controller to better suit my car. Davies Craig did not respond to emails asking for a microcontroller program change for mid engine cars.
Bob Putnam from ERA has had a DC pump running in a car for a good while with no problems. I'm not sure what is different in their setup from mine.
I did have a pump lock up one time while idling in front of the house. Clearances in the pump are close and if allowed to get too hot, it seems like the pump impeller wants to weld itself to the pump housing. I understand DC is making design changes in the area of the seal. This doesn't address the pump impeller problem I had. I've heard of one other person in addition to me that had an impeller lock up
I've had no seal problems.
Plumbing for the Cleveland in the ERA chassis would have been difficult if not impossible using a mechanical pump. The electric pump fit well and works well taking into account the warm up/controller issues and the impeller welding issue.
I believe in the electric pump and feel it can do as well or better than a mechanical pump. It can speed up to max rpm regardless of engine rpm, a benefit going through town in a high gear at low speed.
The controller uses a Microchip PIC controller doing PWM voltage control. It switches the neutral that attaches to the pump NOT the positive voltage.
I believe Davies Craig had cars running their pumps at Le Mans last year. Dual pumps on the car.
Dave