Piston Engines

Question 1

The end of a connecting rod which attaches to the piston is called?

Answer 1

The small end

Question 2

The end of a connecting rod which attaches to the crankshaft is called?

Answer 2

The big end

Question 3

The component in the engine that is subjected to the most amount of force?

Answer 3

The crankshaft

Question 4

What is the crankshaft made of?

Answer 4

Chromium-nickel steel

Question 5

Valves are made of either?

Answer 5

Tungsten or chromium steel

Question 6

The valves are opened by means of the

Answer 6

Camshaft

Question 7

The camshaft is always rotated at -

Answer 7

half the rotational speed of the crankshaft

Question 8

If the valve clearance is excessive -

Answer 8

It result in the valve opening late and closing early

Question 9

Which type of horsepower:

The theoretical power developed in the combustion chamber of a frictionless engine

Answer 9

Indicated Horsepower

Question 10

Which type of horsepower:

This term is used to define the power lost due to friction and driving accessories

Answer 10

Friction Horsepower

Question 11

Which type of horsepower:

This is brake horsepower, and is the actual power available at the propeller shaft. BHP =

Answer 11

IHP - FHP

Question 12

Mechanical efficiency =

Answer 12

BHP / IHP

Question 13

During the induction stroke, the crankshaft will rotate -

Answer 13

180 degrees

Question 14

The inlet valve lead should open?

Answer 14

between 10 and 55 degrees before top dead centre

Question 15

The exhaust valve lead should open?

Answer 15

between 50 and 80 degrees before bottom dead centre

Question 16

Ignition is timed to occur at

Answer 16

between 20 and 25 degrees before TDC

Question 17

Which type of combustion error:

This occurs when the temperature and pressure of the compressed mixture in the combustion chamber reaches sufficient levels to cause instantaneous burning (explosion) of the mixture.The piston then receives a “hammer-like” blow instead of a rapid powerful push. Also called knocking.

Answer 17

Detonation

Question 18

The four causes of detonation

Answer 18

1. High manifold pressure causing excessive temperatures
2. High temperature of intake air
3. Overheated engine
4. Using fuel of a low octane rating

Question 19

Which type of combustion error:

This is caused when there is a hot spot within the cylinders such as red hot spark plug electrodes, glowing pieces of carbon or red hot exhaust valves. These hot spots cause the mixture to be ignited prematurely before the spark plug fires. This can cause an engine running even with magnetos off.

Answer 19

Pre-ignition

Question 20

The two causes of pre-ignition:

Answer 20

1. Excessively lean mixture

2. Incorrect ignition timing

Question 21

pre-ignition will lead to -

Answer 21

detonation

Question 22

To avoid detonation and pre-ignition, what type of octane should be used?

Answer 22

High octane

Question 23

What type of symptom:

This caused by burning oil, and is a sign that there is oil seeping into the combustion chamber, past the piston rings which may be worn or stuck in their grooves.

Answer 23

Blue smoke from the exhaust

Question 24

What type of symptom:

If this is noticed immediately after start, the likely cause is too rich a mixture due to over-priming the engine. This may be accompanied by an initially rough running engine.

Answer 24

Black smoke from the exhaust

Question 25

Valves are closed by means of -

Answer 25

coiled springs