Block 14: Induction & Exhaust - Ignition & Starting

Define Bernoulli’s principal.

The static pressure of a fluid, liquid or gas, decreases at points where the velocity of the fluid increases, provided no energy is added to nor taken away from the fluid. The velocity of the air is kinetic energy and the static pressure of the air is potential energy.

Throttle valve provides what for the engine?

The throttle valve controls the airflow to the engine.

What causes the piston head temp (CHT) to increase dramatically?

Lean mixture (air > fuel) causes too much air to enter the system which may start a fire within.

Define “Supercharger”.

Also known as a compressor, which forces compressed air into the piston engine to adjust power.

At what temp does carburetor ice form?

Between 30 to 40 degrees F.

The three types of common icing includes?

Fuel evaporation/operation ice, impact ice, and throttle ice.

(F.I.T.)

Alternate air valve purpose?

This valve is opened manually (or automatically) and takes hot air from interior engine cowling, thus sending it to components that clogged by ice.

• This valve shall always remain closed until use.

Difference between Primary and Secondary airflow?

Primary airflow is known as core air that mixes with fuel to generate power for an engine.

Secondary airflow is known as bypass air that cools the exterior of the powerplant’s components.

Would would be the compressor ratio be according to the 8083-32B?

Usually 12:1 of air to fuel mixture.

Ie:

140 cubic in of intake

20 cubic in of compression

140/20 = 7:1

Define “MAP”.

Manifold Air Pressure: The amount of fuel to air mixture within an engine's intake manifold.

Difference between internal and external compression?

Internal compresses fuel and air mixture.

External compressed air exclusively.

What type of compressor are most common in modern compressor systems?

Centrifrugal flow compressor

Define “APC”.

Absolute Pressure Controller AKA Density Controller.

• A component that controls a turbocharged engine compressor output.

What two factors aids in engine cooling?

50% air and 50% lubricating oil.

What should be known about critical altitude?

The limit of 29.9 Hg and Hg levels increase at 40k feet altitude and above.

• Engine power reduction will occur. (Less oxygen and thinner air = increased fuel consumption)

Define “Bootstrapping”.

Bootstrapping is an indication of unregulated power change that results in the continual drift of manifold pressure.

• Not considered dangerous, prevented by differential pressure controller.

Is over boost considered dangerous?

Over boosting is dangerous to engine life as manifold pressure higher than the maximum limits set by the manufacturer.

• A pressure relief valve prevents over boost.

In a exhaust system, what areas need extra inspection?

clamps, welds, and Brackets shall be checked more carefully than other components.

• Simply because vibrations cause cracking (most common issue).