Engine Classifications

1. Types of Ignition

• Spark Ignition (SI)
  an SI engine starts the combustion process in each cycle by use of spark plug. The spark plug gives a high-voltage electrical discharge between two electrodes which ignites the air-fuel mixture in the combustion chamber surrounding the plug.
  
• Compression Ignition (CI)
  The combustion process in a CI engine starts when the air-fuel mixture self-ignites due to high temperature in the combustion chamber caused by high compression.
  

2. Engine Cycle

• Four-Stroke Cycle.
  

  A four-stroke cycle experiences four piston movements over two engine revolutions for each cycle.

  
  
• Two-stroke Cycle
  A two-stroke cycle has two piston movements over one revolution for each cycle.

3. Valve Location

• Valves in head (overhead valve), also called I Head engine.

• Valves in block (flat head), also called L Head engine. Some historic engines with valves in block had the intake valve on one side of the cylinder and the exhaust valve on the other side. These were called T Head engines.

• One valve in head (usually intake) and one in block, also called F Head engine; this is much less common.

• Valves in block on opposite sides of cylinder, T head.

4. Basic Design

• Reciprocating
  Engine has one or more cylinders in which pistons reciprocate back and forth. The combustion chamber is located in the closed end of each cylinder. Power is delivered to a rotating output crankshaft by mechanical linkage with the pistons.

• Rotary
  Engine is made of a block (stator) built around a large non-concentric rotor and crankshaft. The combustion chambers are built into the nonrotating
  

5. Position and Number of Cylinder of Reciprocating Engines

• (a) Single Cylinder.

• (b) In-Line.

• (c) V Engine.

• (d) Opposed Cylinder Engine.

• (e) W Engine

• (f) Opposed Piston Engine.

• (g) Radial Engine

6. Air Intake Process

• (a) Naturally Aspirated. No intake air pressure boost system.

• (b) Supercharged. Intake air pressure increased with the compressor driven off of the engine crankshaft

• (c) Turbocharged. Intake air pressure increased with the turbine-compressor driven by the engine exhaust gases

• (d) Crankcase Compressed. Two-stroke cycle engine which uses the crankcase as the intake air compressor. Limited development work has also been done on design and construction of four-stroke cycle engines with crankcase compression.

7. Method of Fuel Input for SI Engines

• (a) Carbureted.

• (b) Multipoint Port Fuel Injection. One or more injectors at each cylinder intake.

• (c) Throttle Body Fuel Injection. Injectors upstream in intake manifold.

8. Fuel Used

• (a) Gasoline.

• (b) Diesel Oil or Fuel Oil.

• (c) Gas, Natural Gas, Methane.

• (d) LPG.

• (e) Alcohol-Ethyl, Methyl.

• (f) Dual Fuel. There are a number of engines that use a combination of two or more fuels. Some, usually large, CI engines use a combination of methane and diesel fuel. These are attractive in developing third-world countries because of the high cost of diesel fuel. Combined gasoline-alcohol fuels are becoming more common as an alternative to straight gasoline automobile engine fuel.

• (g) Gasohol. Common fuel consisting of 90% gasoline and 10% alcohol.

9. Application

• (a) Automobile, Truck, Bus.

• (b) Locomotive.

• (c) Stationary.

• (d) Marine.

• (e) Aircraft.

• (f) Small Portable, Chain Saw, Model Airplane.

10. Type of Cooling

• (a) Air Cooled.

• (b) Liquid Cooled, Water Cooled.