2018 Mercury 4.5L 250HP ECT

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4.5L 250HP ECT



The Next Generation

Featuring a host of engineering innovations, the 4.5L series establishes new standards for power-to-weight ratio, driver experience, acceleration, durability, and ease of maintenance.

  • Built for Marine: Designing a V-6 block solely for marine use allows Mercury to build the 4.5L with the ultimate protection system, using cast-iron componentry where the engine intersects with seawater, and using corrosion-resistant aluminum and composites everywhere else.
  • Powerful Performer: Thanks to its new, long-runner scroll intake manifold which draws in more air and converts it into additional torque, the 4.5L delivers a ground-breaking power-to-weight ratio and gives you V-8 power in a V-6 package.
  • Smooth & Quiet: The 4.5L’s newly designed rear-facing throttle body, anti-whistle throttle plate, engine cover and mounts, lightweight flywheel, fuel-supply module, and structural oil pan all work together to deliver a superior idle, smoothness and low vibration. Resulting in an exceptional driving experience.
  • Corrosion Protection: The MercFusion Paint System creates an outer seal against the elements, while MerCathode® provides automatic protection against galvanic corrosion. For maximum defense against saltwater effects, the SeaCore® industrial hardcoat anodizing system and closed-cooling circuit is available with the Bravo® drive.
  • Sporty Handling: The 4.5L comes standard with Adaptive Speed Control, which automatically maintains engine rpm regardless of load or water conditions. The result is increased throttle response and a sporty feel.
  • Easy to Maintain: When service is required, maintenance is a snap with the front-mounted drive lube monitor, color-coded maintenance points – including easy-to-reach oil filter and fill – and “how-to” videos that can be accessed via the QR code on the label.
  • HP / kW: 250 / 186
  • Maximum RPM (WOT): 4800-5200
  • Engine type: V6, 2-valve/cylinder pushrod
  • Displacement (L): 4.5
  • Displacement (CID/L): 275 / 4.5
  • Bore and stroke: 4.0 x 3.6 in. / 102 x 92 mm
  • Recommended fuel: Unleaded Regular 87 Octane Minimum (R+M/2) or 90 RON 10% Ethanol Maximum
  • Fuel ethanol tolerance: Up to 10%
  • Fuel requirement: 90 RON 10% Ethanol Maximum, Unleaded Regular 87 Octane Minimum (R+M/2)
  • Engine control system: Mechanical Shifting with Optional SmartCraft DTS, Standard SmartCraft with Electronic Throttle Control
  • Fuel delivery system: Computer controlled Multi-Port Electronic Fuel Injection (MPI)
  • Air induction: Performance-Tuned Scroll Intake Manifold
  • Ignition: SmartCraft PCM 112 Digital Inductive
  • Alternator amp / Watt: 70 amp / 882 watt (Belt-Driven)
  • Water drain system: Air Actuated "Season Extender" (Bravo), Easy Drain "Season Extender" (Alpha)
  • Exhaust system: Through prop
  • Cooling system: Water cooled with thermostat; FWC available as factory option (Alpha) and packaged with SeaCore Drive (Bravo)
  • Lubrication system: Integrated wet sump
  • Recommended oil: NMMA Certified FCW 25W-40 Synthetic Blend
  • Engine guardian system: SmartCraft Engine Guardian
  • Dimensions (L x W x H): 28 x 30 x 22 in. / 696 x 740 x 559 mm
  • Weight (engine only): 761 lb. / 345 kg
  • Compatible drives: Alpha, Bravo One, Bravo Three, Bravo Two



Engine Type
V6, 2-valve/cylinder pushrod
250 hp (186 kW)
Bore x Stroke
4.0 x 3.6 in. (102 x 92 mm)
4.5 L


28 in. (696 mm)
30 in. (740 mm)
22 in. (559 mm)
761 lb. (345 kg)


Full Throttle Operating Range
4800-5200 rpm
Fuel Induction
Computer controlled Multi-Port Electronic Fuel Injection (MPI)
70 amp / 882 watt (Belt-Driven)
Water cooled with thermostat; FWC available as factory option (Alpha) and packaged with SeaCore Drive (Bravo)
3 Year Corrosion, 2 Year Limited

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