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Govt. Engineering College Barton Hill Thiruvananthapuram Exp No.
6 Date:
MORSE TEST ON MULTI CYLINDER (MPFI) PETROL ENGINE
Aim: To conduct Morse test on the four stroke multicylinder MPFI
petrol engine and hence
determine the frictional power of the engine
Specifications:
Theory:
Morse Test is used in multi cylinder engines to measure I.P
without the use of indicator. The BP of the engine is measured by
cutting of each cylinder in turn. If the engine consists of 4
cylinders, then the BP of the engine should be measured by cutting
the cylinders one by one. This is applicable to petrol as well as
diesel engines. The cylinder of the petrol engine is made
inoperative (cut out) by shorting the spark plug where as in case
of diesel engine, fuel supply is cut off to the required cylinder.
If there are 'n' cylinders in an engine and all are working, then
(BP)n = (IP)n - (FP)n ----------------------- (1)
Where FP is the frictional power per cylinder.
If one cylinder is inoperative then the power developed by that
cylinder (IHP) is lost and the speed of the engine will fall as the
load on the engine remains the same. The engine speed can be
resorted to it's original value by reducing the load on the engine.
This is necessary to maintain the FP constant, because it is
assumed that the FP is independent of load and depends only on the
speed of the engine. When one cylinder is cut off, (BP)n-1 =
(IP)n-1 - (FP)n-1 ----------------------- (2) From eqns. (1) &
(2)
(BP)n (BP)n-1 = (IP)n - (IP)n-1 = IP-----------------------
(3)
The difference between the measured BP with 'n' and '(n-1)'
cylinders working gives the IP of the cylinder which is made
inoperative (cut out). Similarly IP of all cylinders can be
measured one by one and sum of IP's of all cylinders is the total
IP of the engine.
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The BP of the engine by making each cylinder inoperative can be
measured by any type of dynamometer.
PRECAUTIONS 1. Fuel and lubricating oil are checked and if
needed they are to be supplied. 2. Cooling water inlet and outlet
for engine jacket and brake drum should be opened. 3. Engine should
be started and stopped with no load.
Procedure: The maximum load that can be applied to the engine is
calculated. The engine is started by starter switch after
taking necessary precautions Allow the engine to run for 5
minutes to get get heated up. Set a particular value of load and
adjust speed to the rated speed by adjusting the throttle
(accelerator knob). Record the load and then cut- off the spark
plug of the cylinder- 1, so that no power is developed by that
cylinder. The speed of the engine is then reduced. Bring back the
engine speed to the rated (initial) speed by reducing the load in
the dynamometer. Note down the load from the dynamometer. Repeat
the same for the other cylinders one by one.
Result: The Indicated Power of the engine is determined by Morse
test and hence the frictional power of the given
MPFI engine is calculated as kW.
INFERENCE
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TABULAR COLUMN
Srl. No Working/ FIRING
cylinders Load (kg)
BP
(kw) IP
(kW) 1
2
3
4
5
1 2 3 4
- 2 3 4
1 - 3 4
1 2 - 4
1 2 3 -
IP
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IP of the engine, IP =
CALCULATIONS
MaximumLoad:
. =2
60
Torque, T =
!" = #$%
Where
N = Speed of the engine in rpm,
W = Hydraulic Dynamometer reading
S = spring balance reading (kg) R = Arm length of hydraulic
dynamometer = 320 mm
Now,
BP1 = BP2 = BP3 = BP4 =
IP1 = BP - BP1 IP2 = BP BP2 IP3 = BP BP3 IP4 = BP BP4
Indicated Power of the engine is IP = IP1 + IP2 + IP3 + IP4
Frictional Power of the Engine is,
F.P = IP1 + IP2 + IP3 + IP4 - BP
= -------------
