Engine testing Flashcards
What is engine testing in automotive?
A series of procedures used to evaluate engine performance, efficiency, durability, and emissions.
What is the formula for power in relation to torque?
P = (2πNT) / 60 (Power is a function of torque and speed).
What happens at high torque, low RPM?
Strong pulling ability.
What happens at high RPM, moderate torque?
More power.
What is mean effective pressure?
A constant pressure that, if applied throughout the power stroke, would produce the same work as the varying pressure inside the cylinder.
What is the formula for IMEP?
IMEP = Indicated work done per cycle / Swept volume.
What is the formula for BMEP?
BMEP = Brake work done per cycle / Swept volume.
What is indicated power? (IP)
The total power developed inside an engine cylinder before friction losses.
What is Brake Power (BP)?
The useful power available at the crankshaft.
What is Frictional Power (FP)?
Power lost due to engine friction.
What is the formula for Mechanical Efficiency (Mₑ)?
Mₑ = (BP / IP) × 100%.
What is the difference between BMEP and IMEP?
BMEP accounts for frictional losses and is always lower than IMEP.
What is the formula relating BMEP and IMEP?
BMEP = IMEP × Mₑ.
What is the formula for Torque (T)?
Torque = Force × Radius (Nm).
What is the formula for Power (P)?
P = (2πNT) / 60.
How is power calculated for a four-stroke engine?
Power = P × L × A × S, where:
P = Pressure,
L = Stroke length,
A = Cross-sectional area of piston,
S = Speed of strokes.
What is the formula for fuel consumption (L/kWh)?
Volume of fuel in L × 60 × 60) / (Time in seconds × kW).
What is the formula for fuel consumption (kg/kWh)?
(Mass of fuel in kg × 60 × 60) / (Time in seconds × kW).
What is the formula for the Air-Fuel Ratio?
AFR = (Mass of air per min) / (Mass of fuel per min).
What is the formula for heat supplied to the engine?
Q = Mass of fuel × Calorific Value.
What are the three ways heat is distributed in an engine?
Heat to Power (Pb) – Useful Work
Heat to Cooling Water
Heat to Exhaust and Radiation
What gases are produced from combustion?
CO (Carbon Monoxide)
CO₂ (Carbon Dioxide)
H₂O (Water Vapor)
Trace Gases
Does nitrogen participate in combustion?
No, nitrogen is an inert gas.
What is the Morse Test used for?
To determine Indicated Power (IP), Mechanical Efficiency (Mₑ), and Frictional Power.
How is the Morse Test performed?
By measuring power output with all cylinders running, then turning off one cylinder at a time.
What is BMEP
Brake Mean Effective Pressure (BMEP)
The average pressure that contributes to the useful power available at the crankshaft after accounting for friction losses.
What is IMEP
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
