Re: Question regarding "LUGGING" an engine
Just to pick a figure out of the air, The older OMC engines hit their horsepower at say 4500 rpm, with the full throttle rating being between 5000 to 5500 rpm.<br /><br />The various horsepowers are attained via carburetors with various size throats, different jets, port timing (location of the port passages), exhaust baffle design, and exhaust tuning megaphones, and a few more items no doubt.<br /><br />Unless a boater is a marine engine design engineer, my thoughts would be that attempting to increase a engines horsepower etc via the interchanging components route would be self defeating.<br /><br />Pertaining to horsepower, with the rpm figures stated above, the 85hp and the 140hp hit their rated horsepower at the same 4500 rpm. It stands to reason that lowering the rpm of the 140hp to some degree under that 4500 rpm figure would result in lowering the horsepower.<br /><br />The term of "Lugging" pertains to a engine which has a mismatched propeller in relation to the craft it's installed upon, a prop with usually too much pitch. This result is that, at full throttle, the carburetor butterflies are wide open and the timing is at the full spark advance point, but due to the prop mismatch the engine cannot obtain the proper rated rpm. In short, what's being taken in by the engine cannot be expelled.<br /><br />The result of the "Lugging" is a thick sort of white waxy like substance build up on top of the pistons..... very thick! This substance might resemble a thick carbon build up except for its color and the fact that it is not as hard. Whatever the case, the fact that it's there decreases the engine's performance.<br /><br />Although the OMC engines are designed for full throttle performance of a unlimited time span, when properly matched (Engine/Boat/Prop), it is fully acceptable to run any of them at a lesser rpm also for a unlimited time span. The exception being trolling at an extremely low rpm with a high horsepower engine... they have a tendency to eventually load up on fuel somewhat.<br /><br />In automotive terms.... just because ones vehicle, and the related engine at a certain rpm will attain a certain horsepower and do 130 mph, one doesn't obtain that hp rated rpm and drive that fast on a regular basis.<br /><br />Now, to answer your first question.... Yes(grin).
