 RE: Does mounting the engine higher increase top-end?
Actually yes and yes to a point. The more lower unit that's in the water the more drag, which is why the sum total of twin engine horsepower applications usually won't produce the same performance of single engine same horsepower (ie twin 150's vs, single 300). Most props today are designed to be partially surface piercing though most folks don't realize they're operating that way. The more you raise the motor the less ability the prop has to hold the bow up meaning you can trim the motor out further to get same bow lift and get even more lower unit out of the water (if you don't believe that can make a big difference go trim your motor on a level trailer from full tuck to to full trim - it can raise the lower unit as much as 4"). If you get the prop too high it will loose bite and cost you speed and performance. Also keep in mind that in rough water the prop can't get a proper bite and will slip at "optimal smooth water settings", making a jack plate or a lower, compromise setting a necessity. Some bow heavy boats benefit from putting the motor lower because it's necessary to lower the motor further in the water for the motor to get the leverage needed to hold the bow-up (jack plate helps a lot here). Don't forget to keep a close eye on water pressure if you change motor height, many combinations will have the prop hanging on really well even when they're too high to keep good water pressure - good way to burn up a motor.
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19 Custom Aluminum, 150 Yamaha
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