Yamaha F225 Page 2
F225 —By Capt. Bill Pike — January 2002
Bound for Glory
|Part 2: Yamaha F225 continued|
Yet Yamaha’s engineers stuck to their drawing boards. They were sure the size and weight issues haunting their early efforts were largely due to a single developmental oversight: They’d been trying to apply more or less conventional, low-horsepower four-stroke technology to a big, strapping engine, rather than create a compact V-6 four-stroker from a clean sheet of paper. Moreover, they were convinced that coming up with something truly practical would require "thinking outside the box," a concept they were intent on taking to a whole new level.
So the project retreated back into secrecy. More years passed with few, if any, progress reports, either official or unofficial. Then finally, last fall at Boating Week in Orlando, Florida, amid unconfirmed rumors and rumblings of success, the denouement came. Yamaha unveiled a reasonably sized, 225-hp, four-stroke F225 that tipped the scales at 583 pounds, a mind-blowing number considering it was only 50 pounds more than competing manufacturers of 225-hp two-stroke DFI (Direct Fuel Injected) motors were reporting. Although no working specimens were available for immediate testing and wouldn’t be for a couple months (reportedly due to ongoing R&D with various boatbuilders), excitement ran high, and an Innovation Award was conferred.
But cynics remained skeptical. Sure, the size and weight of the new engine looked good, they grumbled, but what about performance? What kind of showing would the F225–and its sidekick, the F200–make in terms of hole-shot? Would throttle response be muscular or mushy with "dead spots" where throttle movement engendered no change in torque or speed? And perhaps most important of all, would the F225 just plain function properly? I’ll never forget standing alongside the new motor at the Boating Week intro and hearing a guy behind me whisper, "Hey Bill, think it’ll actually run?"
Too bad I didn’t know then what I know now. The new F225 not only runs, it rears back, takes a deep, highly efficient breath, and runs. But before I begin hitting the highlights of this phenomenon, a short explication of the engine’s inner workings is in order, starting with the most striking feature: a reversal of the configuration found in most outboards, two- or four-stroke, as well as most modern automobiles. Instead of mounting the intake system inside the ‘V’ of the cylinder banks and the exhaust system on the outside, Yamaha affixed six tuned intake runners on the outside of the block and placed the exhaust tracks that vent downward through the prop on the inside.
When combined with weight- and size-reducing measures like the incorporation of small, inward-turned fuel injectors and throttle valves in each intake runner (instead of a big, space-consuming, less-efficient central throttle body) and an in-bank exhaust system that replicates compact two-stroke design, it generated a piece of pure innovation–a V-6 four-stroke that’s both narrow (thanks to a 60-degree block) and comparatively light. A couple of other trick features that abet the scenario are a top-mounted flywheel, with a space-saving direct-drive alternator underneath, and a 24-valve, double overhead cam (DOHC) design that, by fine-tuning valve timing and nixing bulky rocker arms and other mechanicals, cuts down on size, complexity, noise, and vibration.
All this stuff sounds great, of course. But hands-on experience is the surest way to ascertain the truth of any new product. So recently, with the assistance of the friendly folks at Mike’s Marine Supply of Panacea, Florida, I got behind the wheel of a new Pro-Line 27 Express equipped with a pair of F225s. My overall impression was about as good as it gets. For starters, the comparatively light 5,900-pound Express showed no evidence of excessive trim "by the stern" as she lay tied alongside a dock at Port Panacea–in other words, the stern did not appear to be overly weighed down by her outboard arsenal. The engines started instantly, and shifting via the Yamaha single-lever binnacle control was seamless and smooth. Sound levels at idle were just a few dBs over the level of normal conversation (65 dB-A), and even toward the top of the rpm register they were several dBs lower than 225-hp EFI engines I’ve tested for PMY (see "Hot Shot," March 1999). Finally, the F225s ran virtually smokeless and vibration-free. Throttle response and acceleration were so sporty I had to tell passengers to hang on during acceleration runs. Moreover, I detected no dead spots or mushiness in throttle response, and the fuel economy numbers were well above what I’ve seen from both EFI and DFI outboards.
The only downside: At $17,440 retail, Yamaha’s new 225-hp four-stroke F225 is a bit pricey. But it’s the four-stroke we’ve all been waiting for. In fact, if ever there was a new outboard that’s bound for glory, this baby’s it.
Yamaha Marine Phone: (770) 420-5848. Fax: (770) 420-6165. www.yamaha-motor.com.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.