Idling at 700rpm, the 40 averaged 3.7kt with a combined fuelflow of 12.2 lt/h and just a gentle rumble coming from the above-water exhausts. The twin-lever controls were certainly not appealing but did provide precise low-speed control and with one engine ahead at 1000rpm and the other astern at 1500 the hull could be quickly spun in its own length without using the 24 volt bowthruster fitted. Spinning 21 x 22.5 inch four-bladed props and driving through 2.5:1 gear reductions, the 8.1S HO engines were very well suited to this hull, which with half tankage, two adults and various options fitted, displaced 9.5 tonnes.īoth engines started instantly, hot or cold, with lower vibration levels across the rev range than the 6.2s tested in a 340. All Sundancers above the 340 (formerly the 375) have V-drive inboards as standard with the props operating in tunnels that reduce shaft angles to around 10 degrees and raise the prop tips above the hull bottom for reduced draft and easier slipping. Lifestyle Marine provided twin units for evaluation in a Sea Ray 40 Sundancer, which measures 12.49 x 4.01m and has a 19 degree transom deadrise. However, reversing the engines compared to sterndrives does limit access to the engine oil dipsticks and serpentine belts.Ĭompared to the 6.2, which has the same dimensions and weight as the 5.7 or 350 MAG MPI Horizon, both 8.1S models are somewhat bulkier and with a Velvet Drive box are 1194mm long (up 102mm), 838 wide (up 92) and 610mm high (up 51mm and again measured from the crankshaft centreline). The V-drive demo units from Lifestyle Marine (02 4959 1444) were fitted with ZF 63 IV boxes, remarkably compact units considering the engine torque they handled. The 8.1S is available with either Borg Warner Velvet Drive or ZF gearboxes and with the Velvet Drive the combined engine/box weight is 513kg, only 19 per cent heavier than the similarly-equipped MX 6.2 MPI Horizon inboard, which develops 320.4hp at 4800rpm. And then there's SmartCraft, which displays fuel tank level, boatspeed, fuel/operating range, fuel efficiency, total fuel used and of course realtime fuelflow. The “Engine Guardian” system has more than 40 sensors to warn of any engine operating problems and in the event of low oil pressure or high coolant temperature it will progressively reduce engine rpm. ![]() The sequential multipoint fuel injection system incorporates Mercury Marine's PCM 555 microprocessor control that optimises fuel delivery for each cylinder according to engine rpm and load and ambient temperature and barometric pressure. The HO has an individual ignition coil per spark plug which reduces radio interference “noise”. Both engines have platinum-tipped spark plugs, watercooled fuel systems to reduce vapour lock, water/fuel separators and remote oil filters mounted at rocker-cover height for easy replacement.Īs with the smaller engines, a serpentine belt drives the high-mounted 14.1 volt, 65 amp voltage-regulated alternator and the cooling water pumps. The standard closed-circuit or heat exchanger cooling increases engine lifespan through reduced cylinder wall condensation and cuts maintenance intervals to normally once a year for oil and filter changes. The standard 8.1S inboard develops 370hp at the crankshaft at 4400rpm and has a Wide Open Throttle rev range of 4200-4600, whereas the HO develops 419.6hp at 4600rpm with a WOT rev range of 4400 - 4800.īoth engines have pushrod-actuated crossflow overhead valves and hydraulic lifters for reliability and 9.1:1 compression ratios necessitating Premium unleaded 95 RON petrol. ![]() The HO designation stands for "High Output" because the 8.1 is available in two outputs. Displacing 8.1 litres or 496 cubic inches, the 8.1S HO has a 108mm bore and 111mm stroke. Although the 8.1S HO has the same 90 degree V8 powerhead design as its 5.7 and 6.2 litre counterparts, it's unusual amongst petrol V8s in that it's an undersquare engine.
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