Marine automobile engine
Encyclopedia
Marine automobile engines are types of automobile
petrol-
or diesel engine
s that have been specifically modified for use in the marine environment. The differences include changes made for the operating in a marine environment, safety, performance, and for regulatory requirements. The act of modifying is called 'marinisation'.
All of the "Big 3" American auto companies have had engines marinised at some point. Chrysler is notable, because the company marinised engines in-house through Chrysler Marine, as well as selling engines to third parties such as Indmar or Pleasurecraft Marine.
General Motors marine automobile engines are based on a gasoline truck engine. That means four-bolt main bearing caps instead of just two; sometimes the crankshaft is forged steel and the pistons an upgraded aluminum alloy. Most importantly the camshaft profile is different with the overlap ground to 112 degrees instead of 110. Expansion plugs are bronze to better fight corrosion. The head gasket's metal O-ring is also more corrosion resistant.
Fuel systems (petrol/gasoline engines)
Fuel systems (diesel engines)
Cooling systems
However, since the introduction of electronic fuel injection, and electronic engine management systems to marine engines this is not nearly as common. Engines equipped with a suite of electronics are LH rotation. The rotation is reversed for the propeller in the transmission.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
petrol-
Petrol engine
A petrol engine is an internal combustion engine with spark-ignition, designed to run on petrol and similar volatile fuels....
or diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
s that have been specifically modified for use in the marine environment. The differences include changes made for the operating in a marine environment, safety, performance, and for regulatory requirements. The act of modifying is called 'marinisation'.
All of the "Big 3" American auto companies have had engines marinised at some point. Chrysler is notable, because the company marinised engines in-house through Chrysler Marine, as well as selling engines to third parties such as Indmar or Pleasurecraft Marine.
General Motors marine automobile engines are based on a gasoline truck engine. That means four-bolt main bearing caps instead of just two; sometimes the crankshaft is forged steel and the pistons an upgraded aluminum alloy. Most importantly the camshaft profile is different with the overlap ground to 112 degrees instead of 110. Expansion plugs are bronze to better fight corrosion. The head gasket's metal O-ring is also more corrosion resistant.
Safety modifications
Electrical systems- Marine starter motor — it has an internal screen to minimize the egression of spark movements.
- Marine alternatorAlternatorAn alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...
differs from an automobile alternator — it has an internal screen to minimize the egression of spark movements.
Fuel systems (petrol/gasoline engines)
- Fuel pump vented — if the fuel pumpFuel pumpA fuel pump is a frequently essential component on a car or other internal combustion engined device. Many engines do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine...
diaphragm ruptures, then the excess fuel will be directed into the carburettor. This kind of fuel pump is referred to as a marine fuel pump. - Marine carburettorCarburetorA carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....
does not allow the overflow into the boat engine compartmentEngine roomOn a ship, the engine room, or ER, commonly refers to the machinery spaces of a vessel. To increase the safety and damage survivability of a vessel, the machinery necessary for operations may be segregated into various spaces, the engine room is one of these spaces, and is generally the largest...
. - Spark arrestor on the air intake (carburettor or electronic fuel injectionFuel injectionFuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
) — a wire mesh screen on the spark arrestor cools any internal flame or spark created by back-fireBack-fireA Back-fire or backfire is an explosion produced by a running internal combustion engine that occurs in the air intake or exhaust system rather than inside the combustion chamber. The same term is used when unburned fuel or hydrocarbons are ignited somewhere in the exhaust system. A visible flame...
, thereby preventing it from igniting fuel vapours inside the engine compartment.
Fuel systems (diesel engines)
Cooling systems
- Marine automobile engines are water-cooled; drawing raw water in from a pickup underneath the boat. In an open cooling configuration, the raw water is circulated directly through the engine and exits after passing through jackets around the exhaust manifolds. In a closed cooling configuration anti-freeze circulates through the engine and raw water is pumped into a heat exchanger. In both cases hot water is released into the exhaust system and blown out with the engine exhaust gasses.
- The transmission oil cooler is cooled by raw water.
Performance modifications
- The marine distributorDistributorA distributor is a device in the ignition system of an internal combustion engine that routes high voltage from the ignition coil to the spark plugs in the correct firing order. The first reliable battery operated ignition was developed by Dayton Engineering Laboratories Co. and introduced in the...
does not have a vacuum advance. Vacuum advance is normally actuated at high engine revolutions per minuteRevolutions per minuteRevolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...
(rpm) in low load situations - and this situation generally does not occur in the marine environment. Under normal operation, high rpm generally means high engine load.
Engine rotation
- Many marine engine crankshaftCrankshaftThe crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
s rotate in the opposite direction when compared to an automobile engine; RH rotation instead of LH rotation. This difference requires, depending on the engine design, a different camshaft, a different distributor gear, a different oil pump and different crankshaft seals.
However, since the introduction of electronic fuel injection, and electronic engine management systems to marine engines this is not nearly as common. Engines equipped with a suite of electronics are LH rotation. The rotation is reversed for the propeller in the transmission.
External links
- Boatbuilder's Handbook Downloads from the U.S. Coast Guard
- Marine Diesel Engines from Volkswagen Marine