This document defines key terms related to internal combustion engines, including bore, stroke, top dead center, bottom dead center, clearance volume, swept volume, compression ratio, and piston speed. It explains these terms and how they relate to engine components like the piston and cylinder. The document also discusses other related terms such as direct injection, indirect injection, smart engines, engine management systems, wide open throttle, ignition delay, air fuel ratio, and fuel air ratio.

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.