Crank driven vs block mounted raw water pump pros/cons

[Scott Danforth]

must have done a few hundred heat exchanger setups in my prior life. you need to make sure the expansion tank is about 20% of the total system capacity. you need about 10% for draw-down and 6% for expansion.

is this a full system or a half system?

 

[IslandExplorer]

Don't have a pic but my friends is mounted to the bulkhead away from the motor

Haven't decided where to mount it yet but good to know that on the wall is a good option. I do prefer keeping the motor as uncluttered as possible so mounting coolant res on the bulkhead would be sweet.

 

[IslandExplorer]

must have done a few hundred heat exchanger setups in my prior life. you need to make sure the expansion tank is about 20% of the total system capacity. you need about 10% for draw-down and 6% for expansion.

is this a full system or a half system?

Experience is definitely a big plus. That capacity ratio is just what I needed to know, thanks! Definitely don't want an udersized exp tank.. Imagine it would boil over and/or blow a line or something pretty quick. Slightly oversized a bad thing? I have plenty of room.

I am planning to run a full system. This is part of why I want to be sure to run a big enough raw water pump that it should keep up with the cooling flow needed. Read that some surprisingly will overheat while idling bc of pump being too small/low idling pump output. Planning to run a Johnson F6B9. Do you think that might be sufficient? Believe it is used on much higher HP and bigger block V8 motors than mine so I was thinking it would be a good match but I don't really know.
Any thoughts on these points would be much appreciated.

 

[Scott Danforth]

The F6 is more than enough. It's for big blocks

The F5 pump is more than enough

A full system will require a 5" diameter heat exchangers or larger

For plumbing a full system it may be easier to run two in-house thermostats.

Water flow on raw water side..... from seacock and sea strainer would go to the raw water pump. From raw water pump to HX inlet. Raw water outlet to exhaust elbows

Water flow on glycol side. HX discharge to bottom circulating pump inlet. With a 3/4 line running to bottom of surge tank. This is the fill line. A spacer under the thermostat that runs 2 3/4" lines to the manifold supply the manifold discharge goes directly to the heat exchangers after the engine thermostat. The thermostat is sitting on top the spacer. The outlet of the thermostat ties in the two manifolds and runs to the heat exchanger.

Run orificed vent lines from the heads and manifolds to the deareation section of the surge tank.

You still need to run the inleg pump to keep the drive cool. Suck it in and discharge as a drive shower