An electric pump that will move enough water to cool the motor on the street will be very expensive and will be a trade-off anyway. It'll take just as much electrical energy (mechanical energy to drive the alternator to feed the pump) to run it as it took mechanical energy to drive the mechanical pump. There's no free lunch. Spend you money more wisely somewhere else on the car and follow Dave's sage advice about weight. 100 lbs equals 1/10th second at the drag strip.