Re: Y'all see the ad for Evinrude E-tec on TV?
Several reasons...<br /> There is a bit of "fudge factor" built into the ratings measurements. I don't know the percentage offhand, but it's something in the neighborhood of 5-6%. So, it's possible that one 225 is actually only 215, another is 225, and another is 235. Also, as Mercury once did on their Hurricane 10s, horsepower can vary with RPM. For the sake of the argument, say all three motors are rated at 225 hp at 5500 RPM. But, perhaps the Evinrude actually makes 240 at 6000 RPM. Prop it to hit 6000 and you'll have that extra power. May not be the case, but it's possible... <br /> There are also differences in lower unit design. Some might be more hydrodynamic than others. Different gear ratios may come into play. If they set all motors at the same height with the same prop for the test, then it's possible that some gearcases were running deeper or higher than optimum. <br /> Also, torque plays a part, particularly where in the horsepower curve the most torque is made. Motors with good low-end torque may accelerate better, but lack a little on top end. Motors with higher end torque may have good mid-range acceleration.<br /> Lots of other things, too, but those are the most likely...<br />- Scott