|Number of Cylinders||8 Cylinders|
Displacement: 7.44 liters
Power Rating: 483-hp (360 kW @ 5400 RPM)
Peak torque: 516 ft.-lbs. @ 4400 RPM
Ilmor hand-builds this V-8 based on a GM 454 block, and uses plenty of interior components of Ilmor’s design, including forged steel crankshaft, rods, and pistons. This construction lies at the core of these engines’ durability, holding up their end of the deal with good low-end torque and substantial power.
Multiple closed cooling systems use glycol-based coolant and heat exchangers to take heat away from components such as the exhaust manifolds and steering system, keeping everything operating within temperature tolerances for optimum performance and durability. Hoses for the system are molded in the shapes they need to be for the system, rather than using standard hose that is ungainly to bend. This procedure helps ensure proper seating on nipples without creating stress points, and also allows the hoses to mount more closely to the block to keep them out of the way.
The hard-anodized exhaust manifold is glycol-cooled to help prevent corrosion in the upper section. Additionally, Ilmor uses a clever design in the lower pipe, the only section of the exhaust manifold that is raw-water cooled. It is a separate casting mounted to the manifold with a cuff clamp, allowing for an easier (and likely much less expensive) change of that part if it should suffer corrosion. This section of the exhaust manifold is vertical which allows raw water to drain out after every use.
Ilmor makes the more common maintenance tasks easier too. The engines have a recommended oil-service interval of 75 hours with a 150-hour interval for the sterndrive unit (or once annually). All service points are located on the top of the engine for easy access, and the oil filter is prominently placed within its courtesy tray.
The One Drive is a sterndrive unit that looks a little larger than most, but for all the right reasons. For one thing, the lower unit was initially engineered by Yanmar to be coupled with high-torque diesel engines. The One Drive is fitted with forged gears for added durability and less wear-and-tear.
Each drive is outfitted with precision forged gears for durability, counter-rotating propellers for superior acceleration and directional stability, and large rudder dimensions for enhanced handling on single and twin engine boats. The One Drive transom has a significantly larger exhaust output than comparable systems, minimizing backpressure for improved engine performance. The system is also equipped with the latest in active and passive corrosion protection, and is complete with power assisted steering and hydraulic trim.
Maximum Input Speed: 6000 RPM
Gear Ratios: 1.78 / 1.97 / 2.18
Steering Angle: 30 degrees (to either side)
Tilt Angle: 51 degrees (industry standard = 37 degrees)
Trim Zone: –6 degrees to 10 degrees
Propeller System: Contrarotating twin propellers
Propeller Range: 22 / 24 / 26 / 28 inches
Propeller Input: Counter clockwise
Front Propeller Rotation: Counter clockwise
Rear Propeller Rotation: Clockwise
Clutch System: Hydraulic multi-friction plate
Shift Control System: Electro-magnetic
Power Steering System: Mechanical cable with hydraulic power assist (single engine installation)
Trim / Tilt System: Hydraulic
Exhaust System: Integral through hub
Water Pick-up System: Integral through drive
Anti-Corrosion System: Hard anodized and electronic active control
Weight: 253 lbs. (with fluids)
In the twin engine configuration on the 370 SS, the One Drive engages and disengages gears at two shifts per second, thanks to the hydraulic clutch that’s actuated electromagnetically. And because the transmissions are in the sterndrive unit, outboard of the transom, the whole setup runs quieter. The smooth shifting is especially helpful when a twin One Drive installation is used with the One Touch joystick system, which results in the system’s two sterndrives shifting in and out of gear quickly to deliver thrust in conjunction with the boater’s control. And, there is no clunk.
For twin-engine installations of One Drive systems, Ilmor offers the optional One Touch joystick system. The joystick offers easy proportional control and the quick, quiet shifting delivers reliable low-speed maneuvering with the power and torque of the MV8 7.4L engines backing it up. The One Touch allows the boater to rotate the boat 360° within a boat length, as well as crab the boat sideways and diagonally.
Instant Joystick Response. While it actually has nothing to do with the joystick itself, it is when maneuvering the boat in tight situations with a strong current running that most operators need instant response from the propulsion system to joystick commands. Unfortunately, in drives that use a cone clutch, the gears must first be moved to neutral and then to the opposite gear before being engaged to follow the joystick’s command. This is this joystick/cone clutch “two-step” – and the clunk. Ilmor’s joystick and One Drive system shifts at two times per second, for virtually no delay between joystick demand and drive response.
The MERLIN Digital Dashboard engine display shows a variety of engine data and can be equipped with autopilot compatibility. It’s a CAN-based touchscreen instrument panel that comes standard with One Touch joystick systems. Engine data can be rendered in analog gauge format, digital text, or even in a graphical treatment that shows the force vectors applied to the hull – including where the power is coming from – when the joystick is manipulated.
User Friendly. Directional and force-vector graphics that are not available on other digital systems. The control buttons on the frame of the screen let the user change settings when conditions are too rough for effective touchscreen use.
As a standard feature, the MERLIN also logs data to help boaters understand how to use their boats better, including real-time fuel-burn measurement, a great tool to help boaters dial in efficiency. The system can even provide engine data to service providers, to help them diagnose any problems that could crop up, and aid in troubleshooting.
The Ilmor throttle-and-shift control binnacle lets the propulsion system be programmed to optimize performance for the boat on which it’s installed.
Engine Room. On the Formula 370 Super Sport where we tested the Ilmor 483-hp MV8 7.4L with One Drive, the engine compartment is accessed from a switch at the helm that lifts the aft seats with a powered ram. Forward of the engines we find flip-down steps that allow easy access for daily checks and light maintenance, yet still offer access beneath. For more involved maintenance, the lift arm can be easily undone by removing a pin and the hatch can be opened fully.
We are struck by Ilmor’s level of detail in this system, and the company’s familiarity with the needs of a boat owner. But isn’t that what we have come to expect from almost anything Roger Penske touches? (Penske is also an ardent boat owner.) This marine propulsion system seems to exemplify his corporate culture of excellence.
Ilmor’s strength is its engineering and its experience with high-performance engines and drive systems – and their vulnerabilities. Most of its components are outsourced to quality vendors, thus reducing Ilmor’s expense in building a comparatively few engines for the marine market. And, that is one of its strengths: It is not saddled with old technology that is the company’s legacy.
The selection of the Yanmar sterndrive transmission and lower unit is a prime example of this quality outsourcing. By utilizing this drive and integrating it into a larger Ilmor propulsion system with engine, joystick, and MERLIN diagnostics, Ilmor has been able to create an excellent system for more refined maneuvering and cruising – and we suspect it is better and far more affordable as a result.
Warranty. The system has a 5-year/500-hour limited warranty. This is putting Ilmor’s money on the table where it counts.
While the instant shifting, no clunk, MERLIN joystick vector graphics, cool-looking engines with its painted aluminum air intake, and its 483 horses, are all terrific features, we think that the system’s potential for reliability and high owner satisfaction is its most important attribute.