Four-Stroke Outboard Engine Test: Twin Yamaha 115s vs. a Single Yamaha 225
In this outboard engine shoot-out, we pit twin Yamaha four-strokes (115 hp each) against a single Yamaha 225-hp four-stroke. The motors were tested on 23-foot recreational fishing vessel from Angler Boats.
In Powerboat Reports’ constant quest to find more fuel-efficient propulsion packages, we decided to compare two identical boats (Angler 23 VBX center consoles)—one powered with a single four-stroke outboard (Yamaha F225), and the other with twin four-stroke engines (Yamaha F115s). PBR testers recorded fuel flow, noise levels, speed, and calculated mileage and range figures. The boat with one engine kicked butt in every category, with the greatest advantage coming at trolling speeds (7 mph). The boat with the F225 also costs less than the boat with the twins.
We want to help you buy the right propulsion package for your boat. Many boat manufacturers offer both single and twin-engine applications. With the increased reliability of today’s four-strokes, the appeal of a second engine as a backup has lessened to a great extent. Fact is, these engines are more dependable than ever. So why spend money on two, when one could potentially do the job?
Our goal was to find out whether a single 225-hp four stroke could indeed do the job in the areas of speed, fuel economy, and engine-noise levels when matched against a pair of 115-hp four strokes. Sure, the twin-engine setup has a 5 horsepower advantage, but as we’ve reported in the past, horsepower ratings are not based on an exact science. In powerplants this big, with hundreds of horses at work, five horses are negligible
A single Yamaha F225 and twin Yamaha F115s were mounted on identical Angler 230 VBX center console fishing boats. With each boat, PBR testers recorded fuel flow, speed, and noise levels at increments of 500 rpm. We also took fuel and noise readings at trolling and cruising speeds. The charts on page 9 show fuel-burn rates, mileage, and range at 7 mph, 23 mph, and 29 mph. PBR conducts this speed
The engines were tested on identical Angler 230 VBX center consoles. Both had half a tank of fuel and two people on board.
vs. speed evaluation when comparing engines of dissimilar technologies (two-stroke vs. four-stroke) or unequal horsepower. Testing took place on Key Biscayne Bay in Miami. To account for wind and current, testers took fuel flow, speed, and noise levels in two directions and then averaged the figures.
What We Found
We measured significant differences in noise levels between the two engine options, sometimes as high as 10 decibels. At trolling speeds and power settings, the variations were minor (not noticeable to the ear). But at higher speeds, the twin-engine package’s noise levels were an average of 8 decibels higher than the single engine (quite noticeable to the ear). Some of this difference may have been attributable to the fact that we tested on different days, both of which were windy, with considerable variations in measured noise levels depending on the direction of travel.
The single engine also racked up better fuel-economy numbers. At a moderate trolling speed of about 7 mph, the single engine is capable of better than 3.3 miles per gallon (mpg) while the twins just edge over 3 mpg. As one bumps up the speed (to troll lures instead of dead bait, perhaps) to about 10 mph, the single still manages almost 2 mpg quite good considering how much more water drag the slight speed increase adds. At this higher trolling speed, the twin-engine gas mileage drops down to about 1.5 mpg. That’s a big difference when averaged over time. On a single day of trolling, you’re talking about burning 10 or more gallons extra with the twin-engine setup.
The only place the twins even come close to operating for the same cost as the single is at cruising speeds. Still, the single edges the twins at every speed. Using our comparison table, we can see that the single 225 gets better fuel mileage at all cruising speeds. The advantage varies from just about even to as much as two-tenths of a mile per gallon.
Finally, the single engine boat is about 2 mph faster at WOT.
Weight is an issue, too. The twin package adds over 200 pounds to the total weight of the boat and in a bad location, too, right on the transom. With less weight hanging off the transom, the single-powered boat seemed to jump on plane quicker and easier, plus it held its plane at a lower speed.
And then there’s cost. The total retail price of the boat powered with the twin 115-hp Yamahas is $1,600 more than the same boat with the single 225-hp Yamaha. Also consider the greater maintenance cost of caring for two engines. You’ll need to change oil on two engines instead of one. Granted, the smaller 115s hold less oil each, but combined, they require more oil than the single. Plus, you have two oil filters, two fuel filters, two lower units, and more time spent paying the mechanic.
Another important factor to consider is that the single operated at lower rpms than the twins at every speed we tested. When comparing internal combustion engines like these, the one that runs at lower rpms will usually offer more efficient operation and enjoy a longer life. All this adds up to more money spent on the twins over time.
Bottom Line: The single 225-hp engine delivers better performance at a lower price.
Curtesy of Powerboats web site.