Our old engine was a Cummins six cylinder naturally aspirated (no turbo-charger) 5.9 litre diesel that theoretically put out 120 horse power (HP) at 2800 RPM. (I say “theoretically”, because we suspect that it never did develop its specified horse power or torque due to the blow-by problem.) It swung a 21 inch MaxProp through a Velvet Drive 72 transmission with 1.88:1 reduction gear.
I’m sharing all this mind-numbing detail because it represents an essential starting point for what turned out to be a complex multi-factor decision that many other boat owners will eventually be faced with.
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