source:thecartech.com

__Cylinder Swept Volume__(

*V*:

_{c})_{}

where:

*V*= cylinder swept volume [cm

_{c}^{3}(cc) or L]

*A*

_{c}_{ }= cylinder area [cm

^{2}or cm

^{2}/100]

*d*= cylinder diameter [cm or cm/10]

_{c}*L*= stroke length (the distance between the TDC and BDC) [cm or cm/10]

BDC = Bottom Dead Center

TDC = Top Dead Center

* Increase the diameter or the stroke length will increase
the cylinder volume, the ratio between the cylinder diameter/cylinder stroke
called “bore/stroke” ratio.

- “bore/stroke” >1 is called

*over square engine,*and is used in automotive engines
- “bore/stroke” =1 is called square engine

- “bore/stoke” <1 is called=

*under square engine*, and is used in tractor engine__Engine Swept Volume__(

*V*):

_{e}_{}

where:

*V*= engine swept volume [cm

_{e}^{3}(cc) or L]

*n*= number of cylinders

*V*

_{c}= cylinder swept volume [cm

^{3}(cc) or L]

*A*

_{c}_{ }= cylinder area [cm

^{2 }or cm

^{2}/100]

*d*

_{c}_{ = }cylinder diameter [cm or cm/10]

* The units of cylinder swept volume is measured in (cm

^{3}, cubic centimeter (cc), or liter)
- V

_{e}for small engines, 4 cylinder engines is (750 cc:1300 cc)
- V

_{e}for big engine, 8 cylinder engines is (1600 cc:2500 cc)__Compression Ratio__(

*r*):

_{}

where:

*r*= compression ratio

*V*= cylinder swept volume (combustion chamber volume) [cc, L, or m

_{s}^{3}]

*V*= cylinder volume [cc, L, or m

_{c}^{3}]

* Increase the compression ratio increase engine power

- r (gasoline engine) = 7:12, the upper limit is engine pre
ignition

- r (diesel engine) = 10:18, the upper limit is the stresses
on engine parts

__Engine Volumetric Efficiency__(

*):*

_{hv}_{}

where:

*h*

_{V }_{ }= volumetric efficiency

*V*= volume of air taken into cylinder [cc, L, or m

_{air}^{3}]

*V*= cylinder swept volume [cc, L, or m

_{c}^{3}]

* Increase the engine volumetric efficiency increase engine
power

- Engine of normal aspiration has a volumetric efficiency of
80% to 90%

- Engine volumetric efficiency can be increased by using:

(turbo and supper charger can increase the volumetric efficiency
by 50%)

__Engine Indicated Torque__(

*T*):

_{i}_{}

where:

*T*= engine indicated torque [Nm]

_{i}*imep*= indicated mean effective pressure [N/m

^{2}]

*A*

_{c}_{ }= cylinder area [m

^{2}]

_{ }

*L*= stroke length [m]

*z*= 1 (for 2 stroke engines), 2 (for 4 stroke engines)

*n*= number of cylinders

*θ*= crank shaft angle [1/s]

__Engine Indicated Power__(

*P*):

_{i}_{},

_{}

where:

*imep*= is the indicated mean effective pressure [N/m

^{2}]

*A*= cylinder area [m

_{c}^{2}]

*L*= stroke length [m]

*n*= number of cylinders

*N*= engine speed [rpm]

*z*= 1 (for 2 stroke engines), 2 (for 4 stroke engines)

*V*= cylinder swept volume [m

_{c}^{3}]

*V*= engine swept volume [m

_{e}^{3}]

*T*= engine indicated torque [Nm]

_{i}*ω*= engine angular speed [1/s]

__Engine Mechanical Efficiency__(

*h*):

_{m}_{}

where:

*h*= mechanical efficiency

_{m}*P*= engine brake power [kW]

_{b}*P*= engine indicated power [kW]

_{i}*P*= engine friction power [kW]

_{f}__Engine Specific Fuel Consumption__(

*SFC*):

_{}

where:

*SFC*= specific fuel consumption [(kg/h)/kW, kg/(3600 s x kW), kg/(3600 kJ)]

*FC*= fuel consumption [kg/h]

*P*= brake power [kW]

_{b}__Engine Thermal Efficiency__(

*):*

_{hth}_{}

where:

*h*= thermal efficiency

_{th}*P*= brake power [kW]

_{b}*FC*= fuel consumption [kg/h = (fuel consumption in L/h) x (

*ρ*in kg/L)]

*CV*= calorific value of kilogram fuel [kJ/kg]

*ρ*= relative density of fuel [kg/L]