posted 06-08-2004 09:16 AM ET (US)
There are many engines which have a common displacement but are rated at different horsepower. Manufacturers always scale the pricing to match the horsepower. There is a popular notion that a less expensive, lower horsepower model of an engine could be turned into to the higher horsepower version after purchase. Unfortunately, I don't recall reading of many success stories for such conversions.Many anecdotal reports exist of simple devices like throttle stops or flow restrictor plates which could be easily removed to yield more horsepower. Or perhaps just something really simple, like removing all the carburetors, tearing them down, replacing some components, re-installing the carburetors, re-installing the linkage, re-calibrating and synchronizing the carburetors, then finally putting the engine on a dynamometer and seeing if any real increase was obtained. Opps, better put the engine on the dynamometer, first, to get a baseline. No problem for the average outboard motor owner, I am sure.
On modern engines, it gets more difficult. The additional performance may come from code in the engine control module. The engines may be mechanically identical, and the difference in horsepower rating is obtained entirely as a result of the engine control module functions. Just buy a new control module for about $700 and you get the improved horsepower.