### I.C. ENGINES

```I.C. ENGINES
Practical No: 3
(22 Apr, 2014)
Report Writing
• Title
• Date
• Object
• Reason for carrying out the
experiment and whether it s to prove
some theory
• Apparatus
• Specification of engine
Report Writing
• Apparatus
• Specification
of
engine
and
equipment
• Clear description if the apparatus
used
• Illustrated by simple diagrams and
photos
Report Writing
• Procedure
• An account of things done before and
during the experiment
• Results
• Record of all data
• Reading taken before and during the
experiment
• Results should be in tabulated form
Report Writing
• Results
• Formula used foe the calculations
and one specimen of each type of
calculation should shown
• Graphs drawn to show the results
must be clearly marked with
• Title
• Date
• Scales
Report Writing
• Conclusions
• An account of any incident or event
during the experiment
• Suggestions why the experiment and
theoretical results do not agree
• Do not always blame the equipment
Report Writing
•
•
•
•
•
•
Hints
Always write in past tense
Make no personal references
Examples
Weights were placed on the carrier
Reading were observed at two minutes
intervals
• Engine speed was increased
• Temperature was constant
Brake Power Test
• Apparatus
• Hydraulic or electrical dynamometers
are used for the testing
• Dynamometer
• Dynamometer can measure the
output torque when driven by engine
• Also measure input torque when used
as electric motor to drive or rotate
engine
Brake Power Test
• Dynamometer
• The motoring test if carried out when
engine is cold gives a measure of the
load which would be put on the starter
motor when the engine is in the vehicle
• Further tests can be carried out at
various engines temperatures including
extreme starting conditions and with
Brake Power Test
• Dynamometer
• Motoring the engine at normal
working temperature enable the
friction and pumping losses to be
determine
• For pumping losses engine can be
relieved of its effective compression
by removing the spark plugs or
injector the remaining losses are
frictional
Calculation for Power and Torque
•  =
()   ( ) (  )
•  =  ()  ()
•    =  ×
•
=  × 2 ×  × /sec
= 2   ( /sec)
Pb = 2  FL ( rev/sec)
•
•
•  =

)

2 (
60
Calculation for Power and Torque
•  =
• If
2
2
60
• Then
•  = kc

(
)

60
= Constant say kc
Example
• A four cylinder , four stock engine has a piston
area of 0.008 m2 and stock of 0.025 m and it is
tested against a dynamometer with torque arm of
0.4475 m,
• P ( brake power) is given by Fk c1
Rev
min
60
• Torque in Nm by Fk c2
• and b.m.e.p (break mean effective pressure) in
kN/m2 by F k c3
• Where F = break load in N and k c1 , k c2 and k c3
are constants dependent upon the dimensions.
• Find the values of k c1 , k c2 and k c3
Example
•
•
•
•
Data
Formula
Sol
To find k c1
•  =
•  =

(
)

2

(
)

60
Example
• Sol
•  =
•  =
•  =
•  =

)

2(0.4475 ) (
60

)

3 (
60

)

(
20

(
)

• k c1 = 20
Example
•
•
•
•
•
•
•
•
Sol
= F x 0.4775 ( Nm)
k c2 = 0.4775
For k c3
Work done = Force x Displacement( Nm)
= m.e.p x Area x Stock ( Nm)
= pAL
Work done / sec = p x A x L x S ( no of
stocks)
Example
•
•
•
•
•
•
Sol
i.m.e.p = work done / sec
Indicated Power (Pt) = p x L x Ax S
b.m.e.p =  Pt

×p×L×A ×
×4
60×2
×p
×0.125()×0.008( 2 )
60×2

×
×4

Example
• Sol
•
×p

×

30000
• Now Brake Power =
• ×p =
F x 30000
• k c3 = 1500
20
F

×

20
= 1500
=
×p

×

30000
```