Nov. 10, 2008 – HP numbers: Fact or fiction?

There’s little question that performance has made a big return to the PWC market. Once king, it had taken a back seat in recent years as manufacturers made the shift to four strokes, and with that move a shift to a more family friendly orientation for their craft. But with four strokes now a proven success, and the entry-level market seemingly taken care of for the time being, performance is making a comeback. Nearly all top-level machines now best the 200hp mark. Meanwhile, Kawasaki and Sea-Doo continue to duke it out for top honors, pushing the mark as high as 260hp for 2009.
But are those hp numbers accurate? Recent testing at Dream Demo, an annual event held by sister publication Watercraft World, again raised the question, as models with notable horsepower differences finished surprisingly close on the radar gun. Those results — as well as numerous others during the past few years — prompted Powersports Business to take a closer look at just what is in a horsepower number.
What’s true, and what’s just clever marketing? We found the answers buried deep within the Web pages of the Environmental Protection Agency (EPA).
What’s In A Number?
The EPA’s interest in PWC engines is obvious. This is the agency that determines emissions compliance, whether those nifty new four strokes are truly worthy of their clean-and-green reputation. The good news, of course, is that they are. The other news that comes out of this testing, however, is that not all tout their horsepower numbers in the same easy-to-compare, apples-to-apples format.
As part of the EPA testing, manufacturers are required to submit a lengthy list of engine and performance specs, part of which includes the engine’s power output, measured in kilowatts. Like any testing, there’s a format. Each manufacturer is allowed to run the test at up to 5 percent less than peak rpm, using an EPA spec fuel and in the lab, not on-the-water conditions. The end result is a measure of the engine’s power output, which can be converted to its horsepower rating through a simple mathematical formula. Marine journalists first stumbled across this info when looking to get the true scoop on emissions ratings. Now, that same info has revealed yet another interesting comparison between the manufacturers.
Want to do your own research? Find the EPA Web site at www.epa.gov/otaq/certdata.htm#marinesi. Or, just keep reading.
The horsepower battles obviously happen at the top of the food chain, so we looked at the engine in the highest output model from each manufacturer in 2008, and compared the horsepower numbers cited by the company to the figures certified by the EPA. Both Honda and Kawasaki were almost spot on in their numbers. The Honda F-15X boasts 197.3hp on the spec sheet; its EPA-certified figure is 197hp. The Kawasaki Ultra 250X cited 250hp in ’08; its EPA-certification lists 247hp. The unknown in the group was Yamaha’s FX SHO. Partially citing the fact that manufacturers were not listing horsepower fairly, Yamaha elected not to publish horsepower numbers starting with the ’08 model year. Rumored horsepower on the SHO seemed to be between 200-211hp. According to the EPA certification, the boat actually produces 202.5hp. Only Sea-Doo varied significantly between advertised and EPA-certified numbers. On the RXT-X, the company cited 255hp, the highest horsepower number claimed by any manufacturer in 2008. According to the EPA certification process, the engine is actually certified over 20hp lower, at 233.3hp.
Marketing Spin
The answer to that inevitable question is the National Marine Manufacturers Association’s “allowance for manufacturing tolerance.” Simply put, the association’s members long ago agreed to allow a 10-percent leeway, up or down, in advertised horsepower from actual horsepower. The purpose was to allow for a nice round, marketable number, say 250hp, to appear on an outboard engine cowl, rather than one that included a decimal point. That allowance still exists and has carried over into PWC engines. With that explanation in mind, Kawasaki and Honda appear to have played it safe, rounding their numbers minimally to get the desired figure. Sea-Doo, however, appears to have taken full advantage of the allowed 10 percent to reach their advertised 255hp.
When asked for comment, the company failed to address the discrepancy directly. “BRP markets the Rotax 4-TEC 255 marine engine to the enthusiasts, the musclecraft buyers,” read a statement prepared for Powersports Business. “It is the most powerful engine BRP has ever equipped a watercraft with in the 2008 Sea-Doo RXP-X and RXT-X and now the new 2009 RXTiS 255 and GTX Limited iS. These models set new standards in power and acceleration, making Sea-Doo the undisputed kings of watercraft performance.”
Whatever the marketing spin, remember that even the numbers can’t necessarily predict the craft’s performance potential. At last year’s Dream Demo, both the EPA-certified 202hp Yamaha FX SHO, the EPA-certified 247hp Kawasaki Ultra 250X and EPA-certified 233hp Sea-Doo RXT-X finished within 1 mph of each other in top speed, despite a 45hp span between them. More real-world testing of these boats, including the Honda F-15X, bear this out. Acceleration, however, favored the Sea-Doo. Clearly there are a lot of other factors at play in determining a boat’s true performance potential. Said Yamaha’s Andrew Cullen: “Overall performance is the story.”
In short, make sure your sales staff understands the numbers game. Because that might very well be what it is.

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