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Sterndrive Stunner

We check out Mercury Racing's HP1075 SCi sterndrive - a 1075hp (802kW) twin supercharged big-block!

By Michael Knowling

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At a glance...

  • Mercury Racing sterndrive
  • 9.1-litre big-block V8
  • Twin Lysholm superchargers with intercooler
  • 1075hp (802kW)
  • Straight from the factory!
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So you love brute power, huh?

Can’t get enough of it?

Well, check out Mercury Racing’s HP1075 SCi sterndrive – a 557ci (9.1-litre) big-block V8 crowned with twin superchargers and a water-to-air intercooler.

You’re looking at a 1075hp (802kW) of high-tech boating muscle!

The HP1075 SCi is trumpeted as the world’s most advanced sterndrive propulsion system and is pitched at high-end 40+ foot sports boats and Class 1 offshore race vessels. We’re talking about craft worth upward of US$1m.

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The engine – which is hand-built in Mercury Racing’s four-cycle Race Shop – is built on a tall deck iron block with 114mm bores and a 111mm stroke. It features five main bearings with stud fastened steel caps, a balanced steel crankshaft, forged conrods and Mercury Racing aluminium pistons (providing a 8:1 static compression ratio). The aluminium cylinder heads are CNC ported and a high performance roller camshaft actuates the large diameter valves. A heavy-duty valvetrain allows safe high rpm operation.

The HP1075 SCi also boasts a dry sump lubrication system. Three scavenge pumps keep oil away from the crankshaft (to help reduce windage and maximise performance) while a pressure pump is fed by a remote oil tank.

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The big bent-eight is boosted by a pair of Lysholm twin-screw superchargers that are more compact and draw less power than traditional Roots style superchargers. The blowers use a self-contained lubrication system that includes a sight plug. Beneath the blowers is a large water-to-air charge-air intercooler, which receives cooling water from one output branch of a three-stage sea pump (the remaining two output branches feed water to the heads and block). A circulating pump is also used as part of the engine’s complex cooling system.

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Boost pressure from the superchargers is controlled by the engine’s PCM (Propulsion Control Module). A boost bypass valve is continuously adjusted to provide consistent power. The engine receives relatively high boost pressure in sub-optimal running conditions to maintain its 1075hp (802kW) rated output. Supercharger induction noise is significantly reduced through the use of twin Helmholtz air inlet resonators made from carbon fibre. Twin flame arresters also act as air filters.

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The HP1075 SCi’s PCM 03 microprocessor delivers sequential fuel injection using an ultra high-flow electric pump and twin injectors per cylinder. The twin injector arrangement is claimed to provide excellent starting, smooth idle and reduce the chance of stalling during gear selection. Idle speed is a relatively low 800 rpm. The PCM also offers cylinder-specific ignition timing thanks to cylinder-specific knock sensing. The use of direct-fire ignition helps eliminate spark plug fouling and a 65 amp alternator is capable of keeping pace with a host of onboard electronics.

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The HP1075 SCi comes equipped with Mercury’s SmartCraft Controller Area Network (CAN) system. The CAN links various sensors to the PCM and enables communication to an optional SmartCraft SC5000 System View unit. The SC5000 System View comprises a colour LCD screen that can be configured to display information on fuel flow, fuel range, fuel used, rpm, water depth, trim angle, water pressure, battery voltage and more. It also shows detailed maintenance reminders and diagnostic information.

The PCM also incorporates Mercury’s Engine Guardian system – a sophisticated failsafe and engine protection strategy which is used in other Mercury engines.

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The monumental output from the twin supercharged V8 is fed through a Huber 1450 series transmission and Mercury Racing’s Six Drive skeg. The Six Drive skeg is a swept-back design with integrated power trim and steering cylinders to improve handling and performance at high speed. The Six Drive also features a heavy-duty universal joint, forged gears and a driveshaft rated for use up to 1000 lb-ft (1355Nm) of torque. 1.15 to 1.61:1 gear ratios are available and you can choose between left or right-hand rotation.

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As its name implies, the Mercury Racing HP1075 SCi produces a maximum power output of 1075hp (802kW). It requires a strict diet of 98 RON fuel and should be configured to operate to a maximum of 6000 rpm – pretty fast for a supercharged 9.1-litre V8!

Given the extreme technology and performance of the HP1075 SCi, it’s no surprise that this is the first engine to be included in Mercury Racing’s TEAM (Total Engine Application Management) initiative. The TEAM process requires training of all boat builder and dealer staff involved with the installation of the new propulsion system. The TEAM initiative ensures proper installation of the engine using all factory-specified components.

Engine durability is enhanced thanks to a host of anti-corrosion materials and treatments and an elaborate water seal system. The engine is also built to meet ISO 9001:2000 standards and comes with a limited 90 day warranty (for recreational use). The engine can now be purchased in Australia on a P.O.A. basis – just don’t expect it to be cheap!

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The HP1075SCi is currently OEM fitment in new Cigarette, Outerlimits and Nortecsports boats sold in the States. It is also finding a home in the ultra tough (and ultra expensive) Class 1 offshore race boat category. The Ugland Offshore Class 1 vessel (which is based in Norway) uses a pair of HP1075 SCis with a race-spec surface drive system. We’re talking about a 40 foot, 4800kg boat that carries 900 litres of fuel and can reach speeds of around 160 mph (259 km/h)...

Now you get an idea of what this awesome engine is capable of!


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