Marine automobile engines are types of

automobile A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarde ...

petrol- or

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-ca ...

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'.

Background

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 In an internal combustion engine, a head gasket provides the seal between the engine block and cylinder head(s). Its purpose is to seal the combustion gases within the cylinders and to avoid coolant or engine oil leaking into the cylinders. Leak ...

's metal

O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...

is also more corrosion resistant. Examples of the opposite of a marinised car engine also exist, e.g. the 6,2 or 6,5 liter

Detroit Diesel V8 engine General Motors introduced a line of Diesel V8 engines for their C/K pickup trucks in 1982. This engine family was produced by GM through 2000, when it was replaced by the new Duramax line. AM General's subsidiary General Engine Products (GEP) st ...

found in Chevrolet and GMC utility vehicles was originally a marine engine adapted for automotive use.

Safety modifications

Electrical systems

* Starter motors and

alternator An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.Gor ...

s have internal screens to minimize spark egress.

Fuel systems (petrol/gasoline engines)

Fuel pump A fuel pump is a component in motor vehicles that transfers liquid from the fuel tank to the carburetor or fuel injector of the internal combustion engine. Carbureted engines often use low pressure mechanical pumps that are mounted outside the f ...

s are constructed such that if their diaphragm ruptures, the excess fuel will be directed into the carburettor. * Carburetors do not allow overflow into the boat engine compartment. *

Spark arrestor A spark arrester (sometimes spark arrestor) is any device which prevents the emission of flammable debris from combustion sources, such as internal combustion engines, fireplaces, and wood burning stoves. Spark arresters play a critical role in ...

are installed on the engine's air intake (carburetor or electronic

fuel injector Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All comp ...

). The arrestor is a wire mesh screen that cools any internal flame or spark created by back-fire, preventing it from igniting fuel vapours inside the engine compartment.

Fuel systems (diesel engines)

Cooling systems

* Engines are water-cooled, drawing raw water through a pickup at the bottom of 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, while in a closed cooling configuration anti-freeze circulates through the engine and raw water is pumped into a

heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct conta ...

. 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

Distribution

The

distributor A distributor is an enclosed rotating switch used in spark-ignition internal combustion engines that have mechanically timed ignition. The distributor's main function is to route high voltage current from the ignition coil to the spark plug ...

does not have a vacuum advance. Vacuum advances are normally actuated at high

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...

/low load situations, which rarely occur in the marine environment: under normal operation, a high rpm generally means a high engine load.

Lubrication

* Lubricating oil is cooled in a shell-and-tube type heat exchanger by raw water. * The oil sump is bigger and often has a different shape, so as not to affect the boat's stability.

References

External links

marine transmission
from the U.S. Coast Guard
Marine Diesel Engines
from Volkswagen Marine {{DEFAULTSORT:Marine Automobile Engine Internal combustion piston engines Marine engines