After researching various engine options worldwide, Pacific Hovercraft selected the Hirth 3503, a 625cc 70 HP water-cooled, carbureted engine. This engine produces 57 ft/lbs of torque at 6,000 rpm and offers an extremely flat torque curve. (see graph below). What does this mean? Lower engine speeds, lower noise levels, lower fuel consumption, smoother throttle response and longer engine life.

This engine has an operating RPM range less than conventional 2 cycles resulting in a very smooth and quiet running engine with impressive power. The 3503 incorporates Al-Nikasil coated cylinders for superior performance and reliability.

Al-Nikasil is a nickel based material applied in a paste form, when super heated it becomes part of the cylinder itself. Nikasil coated cylinders have a hardened surface that cannot peel and is more wear resistant that steel sleeves. Al-Nikasil provides for a super low coefficient of friction, reducing engine heat and wear. Since the aluminum Nikasil coated cylinders and pistons expand at the same rate, cold seizures are eliminated unlike other water-cooled engines. This is why Hirth engines can handle cylinder head temperatures over 500° F without failure.

Engine Type:
2 cycle, Two cylinder
Bore:
76 mm
Stroke:
69 mm
Displacement:
625 cc
Compression:
9.5:1
HP Output:
70 HP @ 6,500 RPM
Torque:
57 ft.lbs. @ 6,000 RPM
Ignition:
Electronic
Carburetion:
Dual 34mm slide or optional electronic fuel injection
Lubrication:
Fuel mixed with oil @ 50:1 / Blue Max @ 100:1or optional oil injection.
Rotation:
CCW (viewed from output end)
Starter:
12 volt electric, plus a manual recoil pull-start as a safety backup.
Alternator:
250 watt / 20 amp, standard
Cooling:
Water cooled
Weight: