The line-up of supercharged Mercury and Mariner Verado four-stroke outboards has been extended to four-cylinder models at 135HP (99.2kW) and 150HP (110kW). The 2004 introduction was for six-cylinder engines from 200HP (147kW) to 275HP (202kW) and followed five years of development, costing Mercury Marine $100 million.

Such is the demand for Verado that the new manufacturing facility at Fond du Lac, Wisconsin, which has the capacity to produce 30,000 units per year, is planned to be expanded to 60,000 units annual capability.

These latest models are being built on a 1.7-litre in-line-four platform. Other than the number of cylinders, the base engine is similar to the larger Verado line, with dual overhead cams, four valves per cylinder and the bedplate with the long bolt design associated with Formula One race cars, providing maximum rigidity and durability from a compact package. The mid-section is similar to the three-litre OptiMax.

Like the six-cylinder versions, these latest four-cylinder Mercury and Mariner engines boast a supercharger and intercooler, combining to give instantaneous torque at virtually any speed.

The charge-air system has an electronic boost valve that maintains correct boost pressure at all times and sends excess air back through the intake. The sequential multi-port fuel injection is electronically controlled for turnkey starting and smooth efficiency.

Throttle response is controlled and enhanced by the SmartCraft digital throttle and shift (DTS). This uses a data cable rather than mechanical push-pull cabling to give smooth, precise gearshifts and no-lag throttle control. DTS, first introduced in 2002, has been tested for more than 50,000 hours in all conditions. SmartCraft is a controlled area network (CAN) bus system that provides extensive real-time vessel management and boat information at the helm.

The Verado four-cylinder four-strokes are available in Long (508 mm) and XL (635 mm) shaft lengths, the latter offered with standard and counter rotation for twin-engine applications.

They are shipped with a universal steering cylinder, with optional electro-hydraulic steering, coupling a power steering pump with the universal cylinder, as on the six-cylinder models.