IC Engine IHP BHP& FHP

1. IC Engine Terminologies
and solved problems
Dr Satish K Sharma
Scientist ( Agril. Engg.)
College of Agriculture JNKVV
Ganjbasoda VIDISHA (MP)

2. Introduction:
Measurements Systems:
Fundamental units { L ‘length’ , M ‘mass’, T ‘time’}
C.G.S. (centimeter, gram, second)
F.P.S. ( foot, pound, second)
M.K.S. (meter, kilogram, second ) becomes
S.I. (systems of international) when add
electric current ‘ampere’, temp. ‘kelvin’ ,
amount of substance ‘mole’
luminous intensity ‘candela’.

5. Complementary units :
Derived units

6. Physical Quantities
1. Scaler quantities : having only magnitude
modulus or number but no direction at all
eg. speed, pressure
2. Vector quantities: having magnitude & direction
eg. velocity , force , acceleration , moment &
electric field. B

7. General Term s
1. Force : Action which changes or tends to change the
state of rest or of uniform motion of a body in a
straight line.Unit is ‘kilogram’ of ‘Newton’
Force = mass x acceleration ,{ 1 kg = 9.8 Newton}
2. Work : When force overcomes a resistance and
causes a body to move ,work is said to be done by F
Work = force (kg) x distance moved (m) = kg.m
3. Power : It is the rate of doing work or work done per
unit time.

8. 4.Energy : capacity to doing work is called energy
(a) Kinetic energy K.E. = =
Where , w= weight in kg , v= velocity in m/s
(b) Potential Energy P.E.= It is due to position of
the body
P.E. = force x distance moved = mg h
5. Electrical power (watt)= Ampere x Volt
Electrical work = Watt x sec. = joules
1 H.P. = 746 watt
1 kw= 1000 watts
1 kw =

9. 6. Torque (kg.metre):
Torque is the twisting or engine’s rotational force &
measures how much of that twisting force is available
when an engine exerts itself.
It is an force acting on an object causes that object
to rotate about an axis or (pivot point)
T = F x r
(Nm, Newton metre which is also called joule)
Hence , torque is inversely proportional to speed or
R.P.M (revolution per minute)

10. Term related to engine power:
1. Mean effective pressure (Mep): avg pressure
exerted during power stroke (kg/cm2)
2. Bore : It is the diameter of the engine cylinder
expressed in cms.
3. Size of the engine : “Bore x Stroke”
4. Horse Power (H.P.) : it is the unit of measuring
power of an engine in metric unit & is equivalents as
1 H.P. = 75 kg-m/sec
= 4500 kg -m/min

11. Indicated Horse Power (I.H.P.): power generated in
cylinder & received by the piston
Break Horse Power (B.H.P.):power available for useful
work at pulley
Frictional Horse Power (F.H.P.):power consumed by an
engine operating itself at no load
I.H.P. = B.H.P.+ I.H.P.
Draw-bar Horse Power (D.B.H.P.): power available at
the draw bar for pulling the farm machine.
D.B.H.P =

12. Mechanical efficiency (M.E.)
It is the ratio of B.H.P. to I.H.P. Is called mechanical
efficiency as under by its formula:
X100
Specific fuel consumption (sfc):
It is the quantity of fuel consumed by the engine per
unit of B.H.P and per unit of time. It is expressed as kg/
bhp.hr or litre / bhp hr.

13. Formula for numerical :
For 4 stroke IC engine
For 2 stroke IC engine

14. Where ,
P= Mean effective pressure in kg/ cm2
L= Length of stroke in metre
A= area of cylinder in cm2
and ‘D’ is bore of cylinder in cm =
N = No. of revolution of crank shaft per minute (rpm)
n = number of cylinders

15. Q. A four stroke 4 cylinder I.C. engine
having engine size is 10 x 12 cms which is
running at 1400 RPM with the mean
effective pressure generating about 5.11 kg/
cm2 .
Find out the I.H.P. of the engine.
Ans. 30

16. THANKING
YOU