Outboard Expert: Squeezing More from Mercury Verado
Less oil equals more power for this Mercury outboard engine.
Mention windage to a sailor, and he’ll think about how big a sheet he can hang on the mast. But mention windage to an outboard engineer, and be prepared for a discussion of the power-sapping effect of excessive oil in the crankcase. Sound boring? What if I told you that by reducing the amount of oil flying around in the crankcase of its 2.6-liter Verado motors, Mercury was able to gain 14 hp? That’s free performance, achieved without burning more fuel.
Three times 300 – the 35-foot Triton 351CC is a high-performance offshore rig that can top 64 mph when powered by three Verado 300 outboards. By reducing internal friction, Mercury was able to extract significant power and economy gains from its 2.6-liter four-stroke outboards.
The subject came up late last summer when I was invited to take a ride with some Merc engineers on a Triton 351 CC rigged with triple Verado 300 motors. These joy-rides are one of the benefits of living just two blocks from the Mercury engineering test center. It was a nice day and the boat was in the water, so why not? In the course of the ride, one of the engineers mentioned that changes to the oiling system were key to taking the 2.6-liter Verado from 275 to 300 horsepower back in 2007. My recollection was that a new camshaft and recalibrated fuel injection and spark timing were responsible for the power boost, but nobody from Merc mentioned oil in 2007. Well, now I have the rest of the story.
What Mercury accomplished is “windage based friction reduction,” essentially by reducing the amount of oil in the atmosphere of the crankcase.
The original Verado platform peaked at 275 hp. Mercury was able to make the jump to 300 horsepower in large part by reducing parasitic power loss due to internal friction.
“Windage is the resistance encountered when passing through a substance,” explained Verado platform manager Steve Miller. “Wave your hands in the air and it’s easy. Waving them in oil is a lot harder. When the crankshaft is spinning around it creates a low pressure area that attracts oil, which swirls around the crankcase. We need some of that to cool and lube the bearings, but excessive oil just robs power because the crankshaft has to push through it.”
Mercury was able to reduce the amount of oil falling out of the crankcase by 33 percent, from 60 liters per minute to 40 liters per minute, according to Miller. This was accomplished in part by switching from cast to stronger, more-durable forged pistons, and then eliminating the oil jets that were employed to cool the cast pistons. The forged pistons do not require cooling jets. Next, changes were made to better control the oil in the crankcase. Oil dams, which look like raised ridges in the crankcase casting, were used to reduce the area of open space around the crank lobes, so there’s “less oil hanging around,” according to Miller. Finally, new main bearings with “eccentric grooves” keep oil from squirting out the end of each bearing only to be flung around the crankcase. The result was 14 free horsepower, or to look at it another way, the same power with less fuel consumption. The new intake camshaft profile and calibration tweaks got Mercury the rest of the power it needed to take Verado to 300, and in the hands of Mercury Racing, 350 horsepower. The rest of the Verado line simply became more fuel efficient.
“We gained 13 percent at wide-open throttle, and 21 percent in fuel economy at cruising speeds, which is important because that’s where people really use the motor,” said Miller. “The new 300 has about the same fuel economy as the old Verado 275.”
Mercury offers some efficiency comparisons at its Range Plus webpage.
Mercury gives its 1.5-liter two-stroke platform a boost in performance and bass-rig styling with this new OptiMax 115 Pro SX.
Mercury Offers New Motors for Bass Anglers, and a New Big Tiller
Mercury has introduced two new direct-injection two-stroke OptiMax Pro XS outboards. The 3.0-liter V6 OptiMax 200 with a 20-inch shaft will now be offered in the Pro XS livery that looks hot on a bass rig. This will be a powerful option for boats with a 200-hp rating. For those looking at a smaller boat, Merc offers the new OptiMax Pro XS 115, a tuned-up version of the standard 1.5-liter OptiMax 115. According to Mercury, carbon fiber intake reed valves and a revised intake tract combine to allow this motor to flow more air, so it can also burn more fuel and make a little more power. The result is a “hot” 115 that also has the same Pro XS graphics found on the big bass V6 models.
There’s also a new OptiMax 125, which will now sport the most-generous rating in the 1.5-liter, in-line three-cylinder platform. Available with a 20 or 25-inch shaft, this motor will be a nice, lightweight fit on boats in the 17-foot range. At 375 pounds, the OptiMax 125 weighs about 25 pounds less than a four-stroke Yamaha F115 or Mercury 115 Four Stroke.
Now available for 40-to-60-hp four stroke motors, the Mercury Big Tiller places power trim control on the end of the throttle grip and is available with electronic trolling speed control.
Finally, Merc is bringing its Big Tiller concept down to the 40- to 60-hp Four Stroke range. We tested the original Big Tiller in 2007. Sold as an accessory for 75- to 225-hp Mercury outboards, with power assist steering for motors over 115 hp, the Big Tiller put safe tiller controls on the biggest motors. This new version has all of the features of the original, except for the power-assist option. It’s center-mounted and has a front-mounted shift lever for better control. The throttle rotation range of 110 degrees gives the operator good throttle modulation that can be twisted through its range without “re-gripping.” The tiller can be locked in two raised positions. Options for this tiller include an LED cockpit light ($38.67) and an electronic RPM trolling speed adjuster ($59.67). The Big Tiller kits cost $718.57 to $865.00, depending on application.
