Sea water aftercooled versus Coolant?

[Arthurc]

Hi,
Has anyone looked at the advantages and disadvantages of sea water after cooled versus coolant after cooled engines? Specifically I'm curious about options on the AFM series John Deere versus SFM. One thing I see is that the AFM seems to need to jump up an M category to produce similar power, is this a sign that coolant cooled isn't as effective and increases wear?

https://www.deere.com/en/marine-engines/propulsion/powertech-6-8l-6068sfm85/

https://www.deere.com/en/marine-engines/propulsion/powertech-6-8l-6068afm85/

Thank you!
Arthur

 

[rslifkin]

Coolant is hotter than seawater, so the air coming out of the aftercooler isn't as cold for a given input temp. That higher temp reduces how much power the engine can produce safely. However, coolant cooled should be better in terms of aftercooler maintenance.

 

[Lepke]

Some high hp engines have the aftercooler directly after the heat exchanger and some others have a second salt water system/heat exchanger just for the aftercooler. But getting the absolute most hp out of an engine doesn't lead to a long life for engine components.