Would mid range be around 2500 to 3000 RPMs? And what about top end speed that is what I am looking for. The way I see it HP= acceleration and more RPMs= more MPH. Its MPH that I am looking for. Right now Iam not sure if more HP is going to give me MPH.
boat motors are built like dump truck motors. a boat is effectively a dump truck in 4th gear going up-hill in sand.
you need grunt (torque). you need a fat torque curve. Ignore chasing HP.
the RPM's are a byproduct of the engine torque curve and the boat's prop curve
a 2 barrel carb chokes the engine's ability to breath. no breathing, no power on the firing stroke. allowing an engine to breath is what allows it to make power. there are many ingredients in making an engine breath to make power. bore, stroke, combustion chamber shape, cam profile, intake plenum size, and incoming throttle plate size are some of the things that go into the formula to make power. Think of it this way. you can breath thru a snorkel and you can walk around without a problem. now try running with a snorkel. you soon get out of breath and you are back to a walk
that searay is a big boat. that being stated, if you want more speed, you need more grunt. there is no replacement for pure displacement. With the 350, the 4 barrel will help a bit. as Chris stated a few mph. however better yet would be a 383 stroker or moving up to either a big block or a 6.2 LS/LT motor. and a bravo 3 drive. that way you have duo props give you more grunt.
BTW, on big hulls, 120hp extra may only equate to 10mph. YMMV
if you go 4 barrel, add intake plenum volume with a carb spacer. that fattens up the mid-range where the boat needs it to get out of the hole. this is where prop optimization comes in. once the boat is on plane, the power requirements of the hull drop off. a fat mid-range gives allows you to swing a bigger prop, getting you out of the hole with the bigger prop and as a byproduct, it gets you more MPH per RPM.
