by how much will the coolant (50/50 fresh water/antifreeze) temperature increase when it is already 180F flowing into the manifold thru a 1/2quot; ID hose? the coolant will flow out of the back of the block thru 1/2quot; NPT fittings, into the base of the manifolds, then out of the top (dry joint) and into 2 (each manifold has it's own, 1 traditionally used for bypass, the other for the heater core in an automotive application) 1/2quot; auxillary coolant-intake ports on the waterpump. when the water reaches 180F, the thermostat will open flushing the block water to the heat exchanger, but the manifold coolant will always come out of the block and return directly to the pump. my concern is; will i over-heat the coolant? i figure this could be an elegant way of keeping the block at 180 and prevent cold shock as the heated water from the manifolds would mix with the cooled water coming from the exchanger. also, is 1/2quot; ID hose too small? assume an aftermarket water pump.thanks!
The thermostat doesn't just snap open at 180 degrees. It gradually opens and closes over a temperature range that allows the cooling system to maintain an average of 180 degrees.
Your heat exchanger will not create cold shock when coolant is running through. The exhaust manifolds are relatively a small area to exchange heat, the block produces much more hot water. Your water pump is not plumbed with two inlets, rather two outlets. Stick with the factory hose routing and the proper pump, which does not use a bypass system and you won't have any problems.
at one time merc cruiser sold aluminum manifolds. Check with them and see if they are still listed.
