After removal/re-installation of my boat's engine and also replacing most of its transmission, including repair (not replace) of the dual props I now have a much better performance from my boat/engine. Obviously I am not complaining but I am curious.
Previously, max-rpm (WOT) was 3700 and speed @ max rpm was about 33 mph. The engine rpm needed to be above 3600 (around 3650) before it would reach planing speed. When we re-installed the engine (no work was done on the engine, just the coupler was replaced) we spent a good deal of time aligning the coupler and the drive using the Mercury alignment tool (really a barbed shaft so you can feel how easily it goes in/out all the way into/out of the coupler) to make sure we had as good a fit as possible. The props were straightened and chrome plated. I now have WOT rpm at 3850. Boat will reach plane at 35xx rpm and max-speed is about 38 mph. My most economic cruise is at about 3470 rpm, 24 mph, burning 1.9 lt/mi.
I am happy but want to make sure that everything is OK. I thought the engine was rated at 3800 rpm at WOT. Whereas I do NOT go above 3670 rpm at all, is it OK that I have capacity to exceed that? Am I just lucky to have a seemingly well tuned/balanced set up?
Thanks,
Previously, max-rpm (WOT) was 3700 and speed @ max rpm was about 33 mph. The engine rpm needed to be above 3600 (around 3650) before it would reach planing speed. When we re-installed the engine (no work was done on the engine, just the coupler was replaced) we spent a good deal of time aligning the coupler and the drive using the Mercury alignment tool (really a barbed shaft so you can feel how easily it goes in/out all the way into/out of the coupler) to make sure we had as good a fit as possible. The props were straightened and chrome plated. I now have WOT rpm at 3850. Boat will reach plane at 35xx rpm and max-speed is about 38 mph. My most economic cruise is at about 3470 rpm, 24 mph, burning 1.9 lt/mi.
I am happy but want to make sure that everything is OK. I thought the engine was rated at 3800 rpm at WOT. Whereas I do NOT go above 3670 rpm at all, is it OK that I have capacity to exceed that? Am I just lucky to have a seemingly well tuned/balanced set up?
Thanks,
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