Medusa 600

Vanquish the opposition, take no prisoners. 655 horsepower and 695 ft-lbs of torque, Holy Mackerel! Made to compete squarely in the world of diesels, this is the engine that will finally open the eyes of many diesel loyalists whose yearly maintenance bills are higher than the cost of a new Medusa 600!

And still, this monster only weighs 700 lbs, making those engine bays previously occupied by turbocharged diesels feel positively deserted! At an average savings of 4,500 lbs and 96 cubic ft over those monstrosities, what will you do with all that extra capacity? Bigger gas tanks, storage bins, a new freezer? A recent Medusa 600 repower added a head, another one an extra cabin. Seriously. At the very least, you may need to redraw your flotation line.

It is time for those large fishing boats, luxury cruisers and small yachts to lose some fat and feel young again, and for their owners to stop suffering the astronomical expenses that come with big diesels. Step into the light!

Build Sheet

  • Block: DART. LITTLE-M. Splayed 4-bolt main, 1-piece rear main seal, cast iron.
  • Crankshaft: SCAT. 4340 forged stainless steel.
  • Connecting Rods: SCAT. 4340 forged stainless stell, I-beam
  • Pistons: PROBE. Forged aluminum, 8 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 CNCd, 305 cc runners, 119 cc chambers.
  • Valves: BPM. Stainless Steel intake/Inconel exhaust, 2.25" intake/1.88" exhaust.
  • Intake: EDELBROCK. Aluminum, RPM Air-Gap, dual-plane.
  • Ignition: MSD. 8560 Marine Billet Distributor + 6M-2L control box/rev limiter
  • Carburetor: QUICK FUEL. Marine Series 850 CFM, mecanical 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, 540 cubic inches/8.9 liters, 4.5" bore x 4.25" stroke.
  • Power Output: 655 HP @ 5500 RPM, 695 ft-lbs @ 4000 RPM
  • Compression Ratio, Idle & Max RPM: 9.5: 1 CR, 800 RPM idle, 5000 max RPM (rev limited)

Target vessels: