Internal Combustion Engine Theory & Performance

All valve timing positions

After Bottom Center After Top Center Before Bottom Center Bottom Center Bottom Dead Center Before Top Dead Center Exhaust Closes Exhaust Opens Intake Closes Intake Opens Top Center Top Dead Center

In order to properly time the proper valve opening and closing the gears on the camshaft

Half the teeth number ratio of 1:2

Boyle's Law

States that the volume of any dry gas varies inversely with the absolute pressure sustained by it, the temperature remaining constant. - In other words, increasing the pressure on a volume of confined gas reduces its volume correspondingly. - Thus, doubling the pressure reduces the volume of the gas to one-half, tripling the pressure reduces the volume.

During each stroke, the crankshaft rotates 180 degrees. What are the opposing position names?

TDC, top dead center BDC, bottom dead center

What is the purpose of a straight, v, or flat engine firing order?

To eliminate vibration to the extent that this is possible

Boyle's Law Formula

𝑽𝟏/𝑽 𝟐 = 𝑷𝟐/𝑷 𝟏

Charlie's Law Formula

𝑽𝟏/𝑽 𝟐 = 𝑻𝟏/𝑻 𝟐

How does a reciprocating engine operate?

Uses the heat to expand a combination of gases and thus to create a pressure against a piston in a cylinder.- The piston, being connected to a crankshaft, causes the crankshaft to rotate, thus producing power and doing work

What are the five events in four stroke engines?

intake, compression, ignition, combustion, and exhaust.

What are the Four Strokes in a four stroke engine?

intake, compression, power, exhaust

Compression Ratio

volume of space in the cylinder when the piston is at BDC : volume when the piston is at TDC in cubic inches

What is an engine?

Device for convening a source of energy to useful work.- The heat is converted to power (the rate of doing work) by means of the engine.

Diesel cycle unique events

Intake sucks in pure air Compression fuel injected and air compressed Ignition is a result of air temp increasing

Rotary Cycle [wankle] engine

Invented by Felix Wankel in 1957 Four-stage internal-combustion engine which provides an excellent weight-to-horsepower ratio It can be liquid- or air-cooled and consists of a rotor that turns inside an elliptical housing. Problems with the internal seals did not give this engine a very good reputation. The use of supercharging has greatly decreased this engine's weight-to-horsepower ratio.

How is the firing order determined?

The firing order is determined by the relative positions of the throws on the crankshaft and the positions of the lobes on the camshaft.

Two-stroke cycle engine

The intake and compression is one stroke and the combustion and exhaust is one stroke. The two-stroke-cycle engine is mechanically simpler than the four-stroke-cycle engine. Less efficient, less cool, and is more difficult to lubricate; therefore, its use is restricted.

Diesel Engine

The operating principle of the four-stroke-cycle diesel engines superficially resembles that of the four-stroke-cycle gasoline engine except that the pure diesel engine requires no electric ignition.

Charlie's Law

The pressure of a confined gas is directly proportional to its absolute temperature. - Therefore, as the temperature of the gas is increased, the pressure is also increased as long as the volume remains constant

How must the valve operating mechanism on the intake or exhaust valve operate during cycling?

one operation for two turns of the crankshaft