2018 Mercury SeaPro™ FourStroke 90 HP - 20 in. Shaft

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SeaPro™ FourStroke 90 HP - 20 in. Shaft



The most efficient mid-range, working FourStrokes ever.

The SeaPro FourStroke Mid-Range takes it to the next level – unbridled power, unusually compact, uncompromising reliability, unbelievably fuel efficient.

  • Easy to Gauge: Accurate digital information is presented in a clean, easy-to-read gauge for instant, reliable information at a glance. Combined with additional sensors, Mercury’s standard gauges are powerful tools to provide safety and comfort while on the water.
  • Corrosion Resistance: Mercury’s proprietary formula – XK360, is an extremely low copper content aluminium alloy, which leads the industry in corrosion resistance. This makes costly corrosion failures and high labour bills a thing of the past.
  • Repower with SeaPro: The compact size also means older boats that were not initially designed for the weight of heavier four-strokes can now be repowered and reborn to perform at their best with the latest technology.
  • Leading Gearcase Technology: All 75-115hp SeaPro FourStrokes utilize the Command Thrust gearcase. This heavy-duty gearcase allows users to run an oversized prop, sits deeper in the water and incorporates a different gearcase ratio – all designed to improve handling and more easily lift heavier boats.
  • Stiffer Upper Mounts: On the SeaPro range the upper mounts are designed to be also two times stiffer than recreational models to maximize durability. Their longevity makes them ideally suited to the demands and rigors of commercial applications.
  • Bigger Footprint: The larger Command Thrust gearcase creates a bigger footprint in the water, which provides more leverage to control your boat. The larger torpedo, combined with a bigger-diameter prop, can lift a heavy boat onto plane more easily and hold it there at lower speeds without impacting top speed.
  • HP / kW: 90 / 67
  • Engine type: 8-valve single overhead cam (SOHC) Inline 4
  • Displacement (L): 2.1
  • Full throttle RPM: 5000-5500
  • Air induction: Performance-Tuned Scroll Intake Manifold
  • Fuel induction system: Computer Controlled Multi-Port Electronic Fuel Injection (EFI)
  • Alternator amp / Watt: 35 amp / 441 watt with water-cooled voltage regulator
  • Recommended fuel: Unleaded Regular 87 Octane Minimum (R+M/2) or 90 RON 10% Ethanol Maximum
  • Recommended oil: NMMA Certified FCW 25W-40 Synthetic Blend
  • Engine protection operator warning system: SmartCraft Engine Guardian
  • Compatible with SmartCraft digital technology: Yes
  • Starting: Smart Start Electric
  • Controls: Mechanical throttle & shift
  • Steering: Big Tiller; Dual cable mechanical; Hydraulic
  • Shaft length: 20 in. / 508 mm
  • Gearcase ratio: 2.38:1
  • Dry weight *Lightest model available: 363 lb. / 165 kg
  • CARB star rating: 3
  • Bore and stroke: 3.5 x 3.2 in. / 90 x 81 mm
  • Ignition: SmartCraft ECM 70 Digital Inductive
  • Fuel system: Electronic Fuel Injection (EFI)
  • Cooling system: Water-cooled with thermostat
  • Gear shift: F-N-R
  • Trim system: Power Tilt; Power Trim
  • Exhaust system: Through prop
  • Shallow water trim range (degrees): 20
  • Color: Phantom Black
  • Lubrication system: Wet sump
  • Oil Capacity: 5.5 qts / 5.2l
  • Maximum Trim Range: 22° (-6° to 16°)
  • Maximum Tilt Range: 70° (-6° to 64°)
Dry Weight based on lightest model available.



Engine Type
8-valve single overhead cam (SOHC) Inline 4
Bore x Stroke
3.5 x 3.2 in. (90 x 81 mm)
2.1 L
Smart Start Electric


Shaft Length
20 in. (508 mm)
363 lb. (165 kg)


Trim Method
Power Tilt; Power Trim
Propshaft Horsepower
90 hp (67 kW)
Full Throttle Operating Range
5000-5500 rpm
Gear Ratio / Shift
2.38:1 / F-N-R
Fuel Induction
Computer Controlled Multi-Port Electronic Fuel Injection (EFI)
35 amp / 441 watt with water-cooled voltage regulator
Water-cooled with thermostat
Big Tiller; Dual cable mechanical; Hydraulic
Three Year Corrosion, Three Year Limited

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