TERMS CONNECTED TO INTERNAL COMBUSTION ENGINE

1. Mentor:
DEBOLINA MUKHERJEE
Texted From:
R K RAJPUT

2. TERMS CONNECTED TO IC ENGINE
 Bore
 Stroke
 Top Dead Center
 Bottom Dead Center
 Clearance Volume
 Swept Volume
 Compression Ratio
 Piston Speed

3. Bore
 The inside diameter of
the cylinder is called
Bore.
 IC Engine Bore is
denoted by D.
Bore =D
Piston
Cylinder

4. Top Dead Center (T.D.C)
 The topmost position of
the Piston towards the
cover end side of the
engine cylinder is called
Top Dead Center (TDC).
Piston
Cylinder
TDC

5. Bottom Dead Center (B.D.C.)
 The lowest position of the
Piston towards the crank
end side of the cylinder is
called the Bottom dead
Center (BDC).
Piston
Cylinder
BDC

6. Stroke
 As the Piston reciprocates, it has
got limiting upper and lower
positions beyond which it cannot
move.
 The linear distance between
which the piston moves between
the limiting position is termed as
Stroke.
 Stroke = L
 IC engine Stroke is denoted by L
.
Piston
Cylinder
Stroke= L
BDC
TDC
Piston

7. Clearance Volume (Vc)
 The volume contained
in the cylinder above the
Piston, when the [piston
is at the Top dead
center is called the
Clearance Volume.
 Clearance Volume is
denoted by Vc.
Piston
Cylinder
Clearance
Volume
TDC

8. Swept Volume (Vs)
 The volume swept by the
Piston in moving between
the Top Dead Center
(TDC) and Bottom Dead
Center (BDC) is called as
Swept Volume ( Vs) .
 Swept Volume,Vs =
Area of Cylinder x Stroke
Length = ∏/4 D² L
Piston
Cylinder
Stroke= L
BDC
TDC
Piston
Bore =D

9. Total Volume
 When the Piston is
positioned at
Bottom Dead
Center , then
Total Volume =
Clearance Volume
+ Swept Volume
Cylinder
Stroke
Length = L
BDC
TDC
Piston
Bore =D
Clearance
Volume

10. Compression Ratio ( r )
 Compression ratio is the ratio between the
Total Cylinder Volume to the Clearance Volume.
r = ( Vc + Vs ) / Vc
r= Compression ratio,
Vc =Clearance Volume,
Vs = Swept Volume,
Total Volume = Vc + Vs
In modern S.I. engine the compression ratio is 8 to 11
and in C.I. engine the compression ratio is 12 to 24.

11. Piston Speed (N):
 The average speed of the piston is called as Piston
Speed.
 Piston Speed = 2 L N
 L= Length of the stroke
 N= Speed of the Piston in r.p.m.
 Average engine speed for all engine will range
from 5 to 15 m/s.

12. Other Terms associated with IC engine:
 Direct injection (D.I): Fuel injection into the main combustion chamber of the engine.
Engine either have one main combustion chamber or a divided combustion chamber. Divided
combustion chamber is made up of main chamber connected with a secondary combustion
chamber.
 Indirect injection (I.D.I.): Fuel Injection into the secondary combustion chamber of the
engine having a divided combustion chamber.
 Smart Engine: Engine with computer controls that regulates operating characteristics such
as Air Fuel Ratio, Ignition Timing, Valve Timing, Exhaust Control, Intake Timing etc.
 Engine Management System: Control and Electronics used to control Smart Engine.
 Wide Open Throttle (W.O.T.): Engine operated with throttle valve fully opened when
maximum power of speed desired.
 Ignition Delay (I.D.): It is the time duration between ignition initiation and actual start of
combustion.
 Air Flue ratio (A/F): It is the ration of Air to Mass of fuel into the engine.
 Fuel Air Ratio (F/A): It is the ration of Fuel to Mass of Air input into the engine.