posted 10-25-2000 05:41 PM ET (US)
Since the introduction of the Mercury Optimax engines 3 years ago, Mercury has insisted that these engines outperform equivalent sized four strokes, both in EMISSIONS and in power output. For example, they have advertized that the 135 V-6 Optimax is cleaner running than the Honda 130HP four stroke (less emissions) and 5mph faster on the same hull. The only downside, I guess, is that fuel consumption is probably slightly higher. The notion that 4 cycle engines, and worse, diesels, in boats are not air polluters is a myth soon to be broken, as it just has been with pickups and SUV's. Marine 4 cycle engines are where automobiles were 25 years ago, and trucks/SUV's still are, with basically no pollution controls on them at all compared to your passenger car, including no catalytic converters. That's right, the family pickup or SUV is a terrible air polluter, even the 2000 models. They say one day on 2 stroke jet ski is the same air pollution as 100,000 miles in a passenger car! Right now the marine industry is fighting to avoid having to put pollution controls and catalytic converters on I/O and inboard marine engines, but they're going to lose.
This stuff will eat horsepower, and eliminate the noisy open exhausts that the go fast crowd lives on. (It's about time!). But it's definitely on the way, and soon. I guess the only reason the government is allowing a delay, is dealing with the converter heat issue on a boat. So where does all this leave the 4 stroke outboards?
Will they too need pollution controls? Are they going to be able to legislate clean 4 stroke inboards, but not clean 4 stroke outboards?
Who knows (certainly not I!).
My guess is that this new Yamaha 4 stroke, evidently a 2002 model, will be a risky venture, with justifying the additional cost and performance trade-offs over a pair Optimax 225's a problem. The four strokes are also having problems competing on power curves, top speed, etc of these clean 2 strokes. I guess that's why Yamaha has FINALLY brought out their own clean 2 stokes in these same HP ranges. They're playing both options. Only time and buyer reaction will tell the story, I guess.
The other issue is reliability. Traditionally, 4 stroke inboards have not been as reliable, or trouble free, as the 2 strokes. About 90% of boats that I see being towed in are I/O's or inboards. Will these huge 4 stroke outboards have the same reliability problems? We'll have to see.
This one ought to get you guys going!