Mercury Racing’s 565 – with digital throttle and shift (DTS), better fuel economy and more grunt – prompted questions. Part 1 answered “How’d you do that?” by reviewing the 565’s torque and power. Part 2 continues to answer: We’ll discuss 565 fuel and DTS.
Fuel Economy. Miserly fuel consumption is a hidden benefit of digital instrumentation. Not just in the boat, but in our laboratory. Since we designed the 525EFI and 600SCi, we have substantially upgraded our dynamometers and engineering analysis tools. In large part, this was done for exhaust emissions, both design feasibility studies and product development, so that we could remain compliant with regulations. As a side benefit: we gained a capability to look at each individual cylinder’s behavior in much finer detail than ever before. Plus, our incredible technicians have the talent to do so.
This enabled improvements in the 565’s air and fuel delivery – through newly designed intake and cylinder head systems. Furthermore, with better on-engine computers (PCMs), we are able to further optimize each cylinder’s combustion – at fine increments of engine RPM. It was a ton of work. However, the net result is leaner operation, which translates to better fuel economy throughout the engine’s rpm range, but especially at cruise speeds.
Why 89 Octane? Yes, the 525EFI and 600SCi live happily on 87 octane gas. With the 565, we carefully balanced fuel cost and rate of fuel consumption with a target: best customer value. The net result was 89 octane, with 565 calibration, provided lower cost of operation. The slightly higher price of 89 over 87 is far out weighed by the better fuel economy and lower emissions. Also, most places our customers go boating, 89 octane gasoline is readily available on the water.
Digital throttle and shift (DTS). Beyond fuel economy and broad torque – and more horsepower – another big benefit of our 565 is DTS drivability. The 565 employs the same PCM used on Mercury Racing’s 1350 and 1100 packages – only two of them. One manages the engine’s fuel and air; the other, its shifting. The control algorithms are similar. The resulting drivability is indistinguishable from its larger siblings. The control levers are smooth and effortless.
Through shifting, the TCM learns the unique boat loads placed on the driveline by differing boat weight, drive gearing and prop inertia. After a dozen or so shifts, the computer has learned to control the rpm drop from neutral to in-gear. No stalls. Just smooth, docile handling – like a pro around the dock.