I would like to confirm or disprove something I have heard. I have heard that over propping a boat will cause a catastrophic engine failure. Is this true? Why or why Not?
The question was about OVER propping a motor which puts excessive load on and will not allow the motor to pull up to rated RPM, greatly over stressing, and overheating, the motor, radically shortening it's service life and sometimes ends in glorious destruction.
By over propping what I meant to say was: having too much prop (pitch) effectively slowing the motor down while at WOT. Example: only turning 5000 RPM when at WOT and reccomended WOT is 5500-6000 RPM. Also, I know this probably isn't an issue on an EFI, but what I am really curious about is a carbed 2-stroke. Thanks!!
The question was about OVER propping a motor which puts excessive load on and will not allow the motor to pull up to rated RPM, greatly over stressing, and overheating, the motor, radically shortening it's service life and sometimes ends in glorious destruction.
Lean conditions are not related to props. Leaning out, is caused by not enough fuel in the fuel/air mixture. This cause's too much heat, and melts pistons. Generally its caused by air leaks in the fuel system, or too advanced timing.
Over proping and under proping are both not good either, and all three can lead to an expensive repair.
I get the concept of a lean fuel/air mixture, thanks. My question was; if the boat is over propped, and you go WOT, it seems to me that the throttle butterflies would be open, but the engine would not be pulling enough vacuum to pull in enough fuel from the main fuel jet, because it is not spinning fast enough, but all the potential air could come down the venturi, thus more air than fuel.....is this correct?
Think of a stick shift car climbing steep grades at 30mph in 5th gear.
Nothing to do with mixture, just simply stressing the engine outside of its best operating range. Some can take it, some can't. The ones that can't break.
