Engine Formulae Flashcards
Knowing all the engine formulae (7 cards)
What is the formula for volumetric efficiency?
Intake Volume/Swept Volume
Intake volume - amount of air drawn into cylinder
Swept Volume - the volume displaced by a piston during its stroke
What is the formula for swept volume?
Stroke x Cross-sectional area of cylinder
units: cm^3
*Stroke - distance between TDC and BDC
What is the formula for piston displacement?
(pi x D^2 x L)/4
units: cm^3
D - diameter of the cylinder (bore)
*calculates the volume displaced by a piston during its stroke
What is the formula for compression ratio?
Volume at BDC/Clearance Volume or Max Volume/Min Volume
*Clearance Volume - the volume left at the top of the cylinder as the piston reaches TDC
What is the formula for brake thermal efficiency?
(Brake Power/Heat Supplied)*100
Heat Supplied = Fuel Mass Flow Rate x calorific value
What is the formula for brake specific fuel consumption?
Fuel Mass Flow Rate/Brake Power
units: g/kWh
What is the formula for absolute pressure?
Gauge Pressure + Atmospheric Pressure
