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WATERSKI MagazineSuck. Squeeze. Bang. Blow. That's the simple description of what an internal combustion engine does. There was once a time when that's about all it had to do to, so long as it moved the boat along and gave the skier a decent pull. But it seems those times are all but gone.
The advent of fuel injection, advanced engine designs and engine- and fuel-management systems have spoiled contemporary skiers. They no longer tolerate hesitations, hard-start conditions or vapor lock. Today's skiers have become used to things that happen quickly and provide instant gratification. They want performance — right now.
Inboard engine manufacturers intend to fill this demand with a bevy of new power plants, some of which were once more at home in luxury and sports cars than ski boats. Dual-overhead cams and port fuel injection are making their way into boat engine bays all over the place and changing the face of the industry and raising the bar once again.
However, installing these engines in ski boats is a little more involved than slapping on some water-jacketed exhaust manifolds, a rubber-coated starter and bolting it in.
For example, boat engines do not have the benefit of air circulating under the oil pan and through the radiator grille, and that can lead to high oil temperatures. The engines are enclosed in a fiberglass box with no ventilation other than the blower fan. And because dual-overhead cam engines are wider than push-rod engines, cockpit space must be considered. After all, what good is a high-tech engine if you can't move freely about the cockpit? Using new power plants also presents other engineering challenges. Take Indmar's adaptation of Cadillac's Northstar engine for use in MasterCraft's flagship MariStar model line.
Indmar
Cadillac's Northstar V-8 marks the largest single engine marinization in Indmar's 29-year history, according to Carl Seyerle, Indmar's engineering director. Because the Northstar was designed for use strictly in front-wheel drive vehicles — Cadillac Seville, Eldorado and Deville – Indmar engineers faced several challenges.
In addition to creating an all-new flywheel and bell housing, Indmar engineers had to modify the transmission, specifically the pump, to accommodate increased rpm's – from 5,800 to 6,200 – that Northstar delivers.
“That forced us to develop the transmission further, which benefits all applications,” Seyerle says.
Like an optional system available on earlier MariStars, the Northstar uses a full freshwater cooling system, which means lake or ocean water never circulates through the engine. Rather, a mixture of water and propylene glycol courses through the engine and into a heat exchanger cooled by incoming lake water. The high-flow coolant pump delivers 200 percent more circulation through the block, cylinder heads and exhaust manifolds. This allows the engine to operate with less than 10 percent temperature variance.
The engine management computer controls the phased warm-up sequence that limits rpm on a sliding scale until the engine and fluids reach proper operating temperature. Operating temperature is thermostatically controlled to ensure even temperature distribution to all parts of the engine, including the exhaust manifolds.
The exhaust manifolds were designed so that they could be reversed to fit V-drive or conventional direct-drive systems. Cast from aluminum, the manifolds are virtually back-pressure free, which enhances performance and efficiency.
On the other side of the cylinder head, the tuned composite intake manifold seems to take on a split personality. It delivers peak torque at 4,400 rpm — at the mid-range rpm where skiers need it — yet pulls strong up to its peak horsepower at 6,100 rpm. Because of its composite construction, it's lightweight and corrosion proof. Smooth interior surfaces of the manifold boost performance by providing a high charge of dense, low-temperature air.
Working in conjunction with the intake manifold, fuel injectors ensure balanced fuel flow to each cylinder. They optimize fuel efficiency, and make up an important part of Indmar's Fail Safe emergency operation mode, which allows the boat to be driven to the nearest harbor or marina in case of water pump failure or coolant loss. The engine-control module shuts down fuel injectors to an alternating set of cylinders, cooling inoperative cylinders with air. Every four seconds, the ECM shuts down the alternate set of injectors.
The Northstar isn't Indmar's only technological offering this year. It also has taken last year's bulletproof LT-1 5.7-liter V-8 a step further. Borrowing technology from the Northstar engine, the new MasterCraft Power MX Plus uses the same 25,000-volt ignition system. The new ECM-controlled ignition system eliminates the distributor and all the maintenance that goes with it. Seyerle also developed a new intake manifold. Using a large plenum and long runners that decrease in size as they near the cylinders, Seyerle was able to achieve a broad torque curve.
Part of that torque curve also is due to the 1.6:1 rocker arms, which give the engine higher valve lift without changing the camshaft. They allow for a lower compression ratio without substantial horsepower loss. It also means you can use less-expensive 89 octane fuel rather than the pricey 93-octane premium.
Pleasurecraft
Marine
This time last year, PCM built a new 90,000 square-foot production facility at its headquarters outside Columbia, South Carolina. This year, PCM president, Chuck Thurman signed a definitive agreement to purchase Crusader Marine Engine from Thermo Power Corp. Combined, PCM and Crusader have more than 67 years' experience building marine engines. But that's not all that's new at PCM, which has introduced the all-new 8.2-liter Python and massaged its proven GT-40.
At 502 cubic inches, the Python is the largest engine available in a ski boat. Derived from Chevrolet's big block V-8 introduced in the mid 1960s, the Python cranks out 430 horsepower and more than 500 foot pounds of torque. That's 100 more foot-pounds of torque and some 50 horsepower more than the next highest rated inboard. But who needs that much power? Aside from people who can never have too much power, barefooters will appreciate the extra grunt as will
the latest generation
of ski jumpers: the
ski flyers.
Using 20 more feet of rope than traditional ski jumping, higher boat speeds and an altered ramp, ski flying replaced traditional jumping at tour stops this year at Fort Lauderdale, Florida; Charleston, South Carolina; and at the Correct Craft-sponsored Masters Tournament in Callaway Gardens, Georgia. Some competitors remarked last year that the boats didn't have enough power. Python has more than enough power to jettison skiers to distances of 250 feet or more.
Recreational skiers and weekend warriors will appreciate the latest tweaks to PCM's workhorse, the GT-40. Based on Ford's 351 cubic-inch V-8 the GT-40 pumps out 310 horsepower and 375 foot-pounds of torque. For 1999 PCM re-calibrated the engine control module for enhanced driving and reliability.
Like other PCM engines, the GT-40 benefits from a micro-adjustable mounting system and a Power Plus transmission. The mounting system uses large heavy-duty brackets and fine-thread stainless-steel hardware so it can be adjusted to allow perfect shaft alignment for smooth vibration-free performance.
Another PCM feature that makes its engines more trouble-free is its patented fuel-control cell. The cell guarantees constant fuel flow to injectors, protects the entire system from contaminated fuel and eliminates vapor lock, which is when gasoline turns to vapor in the fuel lines.
MerCruiser
Four years ago, MerCruise
r sought to expand its presence in the ski-boat market. During that time, the company has learned a few things – some from its experience with inboard ski boats, and some from its other inboard products.
For example, MerCruiser engineers sent sparks flying with its new MEFI 3 ECM digital ignition system. It is now available on the 330-horse Black Scorpion and the 315-horse MAG MPI.
“It's allowed us to integrate the spark controller into the ECM,” says Bob Novotny, calibration engineer with MerCruiser.
MerCruiser engineers were able to further integrate spark- and fuel-management systems to increase idle stability, improve low-speed engine control and enhance the ECM's altitude adjustment capabilities. The changes also smooth shifting in and out of gear.
“Those few things add remarkably to the control of the system,” Novotny says. “It's really much better than before.”
Additionally, both engines will be fitted with the flush system MerCruiser used on its Horizon engines, which were designed to extend maintenance intervals and increase reliability. The 350 MAG MPI also will feature a new intake manifold and a 90- mm throttle body for better breathing. The flush system features hand-removable blue drain plugs, which eliminate the need for tools to winterize.
