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EXPERIMENT NO. 4

1. Objective: To perform the Morse test on a given multi cylinder petrol engine and to find indicated

horse power, brake horse power, friction horse power and mechanical efficiency of a multi-cylinder petrol

engine.

2. Apparatus:

2.1A multi-cylinder petrol engine with hydraulic dynamometer attachment.

2.2 Tachometer.

3. PRINCILE: The Morse test is only applicable to multi- cylinder engines. The engine first run at

required speed and (B.H.P) is measured. Then one cylinder is cut off by shot circuiting the spark plug.

Then the output is measured by keeping the engine speed constant. The difference of (B.H.P) shows the

indicated horse power of cut out cylinder. In this way the (I.H.P) is measured of each cylinder, and the

total (I.H.P) is calculated by adding all the (I.H.P) values of individual cylinders.

(Considering a four cylinder engine)

Let friction horse power (F.H.P) of cylinder no 1, 2, 3, and 4 be F1, F2, F3 and F4 respectively.

The total friction horse power of the engine (F) = F1 + F2 + F3 + F4.

Let indicated horse power (I.H.P) of cylinder no 1, 2, 3 and 4 be I1, I2, I3 and I4 respectively. Total

indicated horse power of the engine (I) = I1 + I2 + I3 + I4.

Let the total brake horse power (B.H.P) of the engine when all the cylinders are working is B.

So; B = (I

F).

When one cylinder is cut off, (B.H.P) developed by the rest cylinders.

B1 = (0 +I2 + I3 + I4)F.

So; I1 = BB1.

Similarly; I2 = BB2.

I3 = BB3.

I4 = BB4.

The total (B.H.P); B = (WN)/C

Where ; W = Load on the balance arm in kg, N = Shaft speed in r.p.m.

C = A constant i.e. (2000) for B.H.P metric.

Mechanical efficiency = {(B.H.P) / (I.H.P)} 100

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4. PROCEDURE:

1. Before starting the engine check the fuel supply, lubrication oil, and availability of cooling water.

2. Set the dynamometer to zero loads.

3. Run the engine till it attains the working temperature and steady state condition. Adjust thedynamometer load to obtain the desired engine speed. Record this engine speed and dynamometer reading

for the BP calculation.

4. Now cut off one cylinder. Short-circuiting its spark plug can do this.

5. Reduce the dynamometer load so as to restore the engine speed as at step 3 .Record the dynamometer

reading for BP calculation.

6. Connect the cut off cylinder and run the engine on all cylinders for a short time. This is necessary for

the steady state conditions.

7. Repeat steps 4, 5, and 6 for other remaining cylinders turn by turn and record the dynamometer

readings for each cylinder.

8. Bring the dynamometer load to zero, disengage the dynamometer and stop the engine.

5. OBSERVATION:Table no1.

Readings Cylinders

Working.

Speed (N)

In r.p.m.

Dynamometer

reading (W)

In kg.

(B.H.P)

.

(I.H.P) of

cut off

cylinder.

i (1-2-3-4) B -----------

ii (0-2-3-4) B1 I1

iii (1-0-3-4) B2 I2

iv (1-2-0-4) B3 I3

v (1-2-3-0) B4 I4

Table no2.

Engine (B.H.P). Engine (I.H.P). Engine (F.H.P). Mechanical efficiency

{(B.H.P). / (I.H.P)} 100.

6. Conclusion: