Quote:
Originally Posted by Spruill242
'86 23CC with a 2005 Evinrude 225. No name, no number prop. So I don't have a clue on pitch and size. No trim tabs (well currently not working)
WOT is currently 5000rpm and 33-34 knots based on boat mounted GPS. Planes out at 3800-4000rpm. Engine is capable of 6200rpm. New throttle cables so next time I'm down at the boat I'm going to pull the cover off the engine and make sure I'm getting full opening on the TB.
I'd like to be able to get redline if I wanted to (for whatever reason there would be for that) but don't "need" to. 40+ knots at a decent RPM would be nice to make the tower run on a calm day that much shorter but again; that's a want not a need.
Should I start messing with prop sizes or leave well enough alone?
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it's all about load
that motor should be able to run it's max RPM,with the boat loaded in the condition it's normally ran - read that as,if you're running your boat with 4 people,full fuel and 600lbs of gear - duplicate weight conditons
take the boat out and run it on the pin - wide open throttle...record the max rpm you see
check the height of the motor - antiventilation plates out of the water ?
check that the throttle is opening fully...
a motor that's under the rated rpm is overloaded - people often think it's ok,because they never run it hard - that's incorrect,overloaded is overloaded...
every inch of pitch will give approx. 150RPM - problem with that is,when the hull begins to get some air under it,rpm's will climb...read that as,if you're 1,200 rpm down,you won't need to drop 6" in pitch - 2" in pitch is a big difference
a motor being able to reach it's max rpm,is more fuel efficient and it will last longer - overloading the motor,it greatly reduces the durability of ANY motor...