posted 03-25-2007 09:54 AM ET (US)
The models with the "H.O." designation (which is universally assumed to mean high output) have a 1.86:1 "high speed" gear case and are only available in 20-inch and 25-inch shaft lengths. [Oops--not quite true, see below.]The regular models have a different gear case, one with a 1.85:1 ratio, and they are available in 20-, 25-, and 30-inch shaft lengths.
The engine blocks are the same, a 3.1-liter V6. The horsepower ratings and models for this block are
--200 H.O.
--225
--225 H.O.
--250
The H.O. models are intended for high speed applications like 75-MPH or faster bass boats. The design of the gear case has been modified for better performance at high speeds.
The horsepower ratings are confusing. If you compare the engine power ratings in kilowatts as shown on the emission label on the engine, you will see that a 225 H.O. engine produces as much power output as a 250-HP engine. The engine is labeled a "225" but produces more like 225-HP plus ten-percent (which is the usual tolerance given to all power ratings), or about 247-HP.
The odd rating method may be something of an accommodation for certain situations where there is a limit to the rated horsepower which can be used, for example, as might occur in a fishing tournament.
The "H.O." models have different pricing than the standard models. I think in some cases they might have different cowling graphics, too.
Because most Boston Whaler boats are not routinely operated at speeds over 50-MPH, I don't think the "H.O." models of the Evinrude E-TEC have a great deal of application for Whalers.