Engine testing

Question 1

What is engine testing in automotive?

Answer 1

A series of procedures used to evaluate engine performance, efficiency, durability, and emissions.

Question 2

What is the formula for power in relation to torque?

Answer 2

P = (2πNT) / 60 (Power is a function of torque and speed).

Question 3

What happens at high torque, low RPM?

Answer 3

Strong pulling ability.

Question 4

What happens at high RPM, moderate torque?

Answer 4

More power.

Question 5

What is mean effective pressure?

Answer 5

A constant pressure that, if applied throughout the power stroke, would produce the same work as the varying pressure inside the cylinder.

Question 6

What is the formula for IMEP?

Answer 6

IMEP = Indicated work done per cycle / Swept volume.

Question 7

What is the formula for BMEP?

Answer 7

BMEP = Brake work done per cycle / Swept volume.

Question 8

What is indicated power? (IP)

Answer 8

The total power developed inside an engine cylinder before friction losses.

Question 9

What is Brake Power (BP)?

Answer 9

The useful power available at the crankshaft.

Question 10

What is Frictional Power (FP)?

Answer 10

Power lost due to engine friction.

Question 11

What is the formula for Mechanical Efficiency (Mₑ)?

Answer 11

Mₑ = (BP / IP) × 100%.

Question 12

What is the difference between BMEP and IMEP?

Answer 12

BMEP accounts for frictional losses and is always lower than IMEP.

Question 13

What is the formula relating BMEP and IMEP?

Answer 13

BMEP = IMEP × Mₑ.

Question 14

What is the formula for Torque (T)?

Answer 14

Torque = Force × Radius (Nm).

Question 15

What is the formula for Power (P)?

Answer 15

P = (2πNT) / 60.

Question 16

How is power calculated for a four-stroke engine?

Answer 16

Power = P × L × A × S, where:

P = Pressure,

L = Stroke length,

A = Cross-sectional area of piston,

S = Speed of strokes.

Question 17

What is the formula for fuel consumption (L/kWh)?

Answer 17

Volume of fuel in L × 60 × 60) / (Time in seconds × kW).

Question 18

What is the formula for fuel consumption (kg/kWh)?

Answer 18

(Mass of fuel in kg × 60 × 60) / (Time in seconds × kW).

Question 19

What is the formula for the Air-Fuel Ratio?

Answer 19

AFR = (Mass of air per min) / (Mass of fuel per min).

Question 20

What is the formula for heat supplied to the engine?

Answer 20

Q = Mass of fuel × Calorific Value.

Question 21

What are the three ways heat is distributed in an engine?

Answer 21

Heat to Power (Pb) – Useful Work

Heat to Cooling Water

Heat to Exhaust and Radiation

Question 22

What gases are produced from combustion?

Answer 22

CO (Carbon Monoxide)

CO₂ (Carbon Dioxide)

H₂O (Water Vapor)

Trace Gases

Question 23

Does nitrogen participate in combustion?

Answer 23

No, nitrogen is an inert gas.

Question 24

What is the Morse Test used for?

Answer 24

To determine Indicated Power (IP), Mechanical Efficiency (Mₑ), and Frictional Power.

Question 25

How is the Morse Test performed?

Answer 25

By measuring power output with all cylinders running, then turning off one cylinder at a time.

Question 26

What is BMEP

Answer 26

Brake Mean Effective Pressure (BMEP) The average pressure that contributes to the useful power available at the crankshaft after accounting for friction losses.

Question 27

What is IMEP

Answer 27

Indicated Mean Effective Pressure (IMEP) The average pressure inside the cylinder that contributes to generating total power. Since BMEP accounts for frictional losses, it is lower than IMEP. BMEP = IMEP × M