Engines — By
the PMY staff
Gasoline — MerCruiser
|2001 Engine Preview|
Out of the boat, a gasoline inboard joined to a stern drive has a zoomorphic profile. Powerful V-8 above, sleek drive below, it's like a barrel-chested merman in Neptune's mythological honor guard. However (and despite that overwrought metaphor), when you first lay eyes on MerCruiser's new 8.1S Horizon (370 hp) or 8.1S HO (420 hp), the first thing you notice is a nifty little blue hand pump mounted on the heat exchanger. It's part of the new air pressure-actuated raw-water draining system, a convenience designed for those weeks in the spring and fall when nights are freezing cold but daytime weather is pleasant enough to encourage cruising. Pump air into a pair of fittings located near the top of the engine, and within moments valves below open to drain the entire raw-water system. Release the pressure with the pull of a pin, and the valves close again. Boaters reluctant to call a halt to their seasons at the first hint of cold weather will no doubt find this means of quick, if somewhat abridged, winterization attractive. For those hot months of the high season, a water-cooled fuel system combines with a water/fuel separator to forestall vapor lock.
MerCruiser has also designed a special exhaust system for these engines. Aluminum manifolds and stainless steel elbows, both ceramic coated and painted using the electro-deposition process (in which paint is given one electrical charge and the object to be painted the opposite), reduce the weight of the system by 65 percent. Cooling water that used to travel directly between the manifolds and elbows now bypasses a dry joint, so the occasional "weeping" at this juncture should be a thing of the past.
Both the 8.1S Horizon and 8.1S HO are also equipped with an electronic engine-control module made by Motorola. Built into this unit is the PCM 555 processor, the heart of MerCruiser's new SmartCraft system. Thus both the models are SmartCraft-compatible. Available prerigged from a number of boatbuilders, SmartCraft in its most comprehensive version, the SC5000 System View, integrates engine data such as fuel flow, rpm, and temperature with GPS and depthsounder readouts, water, fuel, and waste tank levels--you name it--all on a single LCD screen. In all, the processor gathers information on 64 internal functions while keeping tabs on numerous sensors installed throughout the vessel. Big Brother has indeed gone to sea, but you still call the shots: Through the same SC5000 screen you will eventually control trim tabs and bilge ventilators.
Whether or not you take advantage of this remarkable technology, MerCruiser backs these engines with a standard one-year warranty and offers extended coverage for two, three, or four years.
Boaters interested in cruising at only a slightly quicker pace will be intrigued by another new engine from MerCruiser, one not based on the new GM 8.1. The company enlarged its existing GM 5.7-liter V-8 to 6.2-liters, thanks to a new crankshaft that offers a longer stroke and reconfigured rods and pistons. The new MX 6.2 MPI puts out 320 hp at the prop, produces more torque, and shares many of the performance-enhancing features of the 8.1s, including multiport fuel injection and a billet-steel, special-profile camshaft. Also like the 8.1s, the 6.2 can be mounted as a conventional inboard or with a stern drive.
MerCruiser/Mercury Marine (920) 929-5770. Fax: (920) 926-7070. www.mercurymarine.com.
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This article originally appeared in the May 2003 issue of Power & Motoryacht magazine.