Medusa 500

One engine to rule them all. Same size and weight as the Medusa 400, but putting out a tsunami inducing 550 Horsepower and 560 ft lbs of torque! Only racing gasoline engines or diesels can deliver similar power, but at several times the cost of the Medusa 500.

This engine is the preferred choice for deep V fishing machines, helping those heavy boats reach speeds never thought possible, while cutting hours off oceanic crossings and shaving thousands of pounds of weight from the monstrous diesels that came originally installed. Obviously, less weight and shorter run times translate into a dramatic reduction in fuel consumption.

The Medusa 500 also breathes new life into those large, wide beam cruisers from the 80s and 90s, allowing them to compete against their bloated, modern counterparts, both performance and price wise. There has never been another engine out there, anywhere, anytime, with a power-to-weight ratio comparable to the Medusa 500. Enough said!

Build Sheet

  • Block: DART SHP. Splayed 4-bolt main, 1-piece rear main seal, cast iron.
  • Crankshaft: SCAT. 4340 forged stainless steel.
  • Connecting Rods: SCAT. 4340 forged stainless steel, I-beam
  • Pistons: WISECO. Forged aluminum, -20 cc dish, 9.5:1 CR
  • Camshaft: HOWARDS. Hydraulic roller, lift: int .500/ ext .510, duration @ 0.050": int .225/ ext .231, angle: 110 degrees.
  • Rockers: SCORPION. Full roller, 1.5 ratio, forged aluminum.
  • Cylinder Heads: AFR. Aluminum, fully CNC'd, 220 cc runners, 75 cc chambers.
  • Valves: BPM. Stainless Steel, 2.10" intake/1.60" exhaust.
  • Intake: PROFESSIONAL PRODUCTS. Aluminum, Crosswind, dual-plane.
  • Ignition: MSD. 8560 Marine Billet Distributor + 6M-2L control box/rev limiter
  • Carburetor: QUICK FUEL. Marine Series 750 CFM, dual pump, vacuum secondaries and black diamond coating.
  • Fuel System: HOLLEY 110 GPH marine pump with fuel regulator, 10 micron fuel filter/water separator and AEROMOTIVE flexible steel fuel lines.
  • Exhaust System: MEDUSA. Stainless Steel headers inside stainless steel water jacket, raw and fresh water capable, integrated anode.
  • Cooling System: MEDUSA.  Fully closed, fresh water. 60 GPH crank mounted raw water pump, high flow heat exchanger & 3-year coolant.
  • Alternator: DELCO. Marine 120 AMP.
  • Starter: DELCO. Marine 1.6 kw, top mounted.


  • Type & Displacement:  DOV 90° V8, 433 cubic inches/7.1 liters, 4,185" bore x 3.85" stroke.
  • Power Output: 550 HP @ 5500 RPM, 580 ft-lbs @ 4100 RPM
  • Compression Ratio, Idle & Max RPM: 9.5 : 1 CR, 750 RPM idle, 5000 max RPM (rev limited)

Target vessels: