Old 08-24-2020, 08:25 AM
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Join Date: Jun 2014
Location: Middle Sound, NC
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Air side of turbo runs hot, just from the heat of compression. Turbo compresses air and that means heat. Just about every B or C marine engine has some browning on the air pipes and turbo before the aftercooler. Really dark brown and that thing has been run hard and probably over propped.

You do want to make sure you operate below the prop load line on your particular engine curve. Most of the time if you can reach rated rpm with load below like 95%, you are good to go at cruising speed. But each boat/engine combo is different.

No way is a common rail Cummins rated for 3300 going to reach 3450. Computer starts backing off fuel rate at about 3350.