Fourth Year - Mechanical Power Eng. Dept. First Term - 2016/2017 Internal Combustion Engines

Fourth Year – Mechanical Power Eng. Dept.
First Term – 2016/2017 Internal Combustion Engines
Assignment #1
1- A 4-cylinder, 4-stroke has the following results on the test beds:

Shaft speed = 2500 r.p.m, torque arm = 40 cm, net brake load = 200 N,
fuel consumption = 2 gm/s, H.V = 42 MJ/kg, Area of indicator diagram
(Ad) = 300 mm2, pressure scale (Sp) = 80 kPa /mm, stroke=bore =100
mm, base length of the diagram (Y) = 60 mm.
Calculate : BP, FP, IP, MEP, ηB,th, ηI,th, and ηm .
2- A 4-cylinder, 2-stroke has the following results on the test beds:

Shaft speed = 2000 r.p.m, torque arm = 50 cm, net brake load = 500 N,
fuel consumption = 5 gm/s, H.V = 46 MJ/kg, net area of indicator
diagram = 1500 mm2, pressure scale (Sp) = 25 kPa /mm, stroke=bore
=100 mm, base length of the diagram (Y) = 66 mm.
Calculate : ηB,th, ηI,th, and ηm .
3- Find the air-fuel ratio of a 4-stroke, 1 cylinder, air cooled engine with
fuel consumption time for 10 cc as 20.0 sec. and air consumption time for
0.1 m3 a 16.3 sec. The load is 16 kg at speed of 3000 rpm. Also, find
brake specific fuel consumption in g/kWh and thermal brake efficiency.
Assume the density of air as1.175 kg/m3 and specific gravity of fuel to be
0.7. The lower heating value of fuel is 44 MJ/kg and the dynamometer
constant is 5000.
4- A 4- cylinder, 2-stroke diesel engine with 10.9 cm bore, 12.6 cm stroke

produces 88 kW of brake power at 2000 r.p.m., compression ratio =18.1.
Calculate: (a) engine displacement,
(b) brake mean effective pressure,
(c) torque,
(d) clearance volume of one cylinder,
(e) what is the average piston speed? And what is the piston
speed when the crank angle θ 90 0 a TDC.
5- A 5-cylinder, 3.5 liter SIE operates on a 4-stroke cycle at 2500 r.p.m.

At this condition, ηm = 0.62 and 1000 J of indicated work are produced
each cycle in each cylinder.
Calculate: (a) IMEP (b) BMEP (c) FMEP (d) Torque
If the engine is square (S=B), Calculate:
(a) Specific power (hp/cm2), (b) Output per displacement (hp/cm3), (c)
power lost to friction.
6-The observations recorded after the conduct of a retardation test on a

single-cylinder diesel engine are as follows:
Rated power = 10 kW
Rated speed = 500 rpm
Find mechanical efficiency at half load.
7- A 1500-cm3, four-stroke cycle, four-cylinder CI engine, operating at

3000 RPM, produces 48 kW of brake power. Volumetric efficiency is
0.92 and air-fuel ratio AF = 21:1.
Calculate: (a) Rate of air flow into engine.
(b) Brake specific fuel consumption.
(c) Mass rate of exhaust flow.
(d) Brake output per displacement.
8- A small single-cylinder, two-stroke cycle SI engine operates at 8000
RPM with a volumetric efficiency of = 0.85. The engine is square (bore =
stroke) and has a displacement of 6.28 cm3. The fuel-air ratio FA = 0.067.
Calculate: (a) Average piston speed.
(b) Flow rate of air into engine.
(c) Flow rate of fuel into engine.
(d) Fuel input for one cycle.
9- A single-cylinder, four-stroke cycle CI engine with 12.9-cm bore and

18.0-cm stroke, operating at 800 RPM, uses 0.113 kg of fuel in four
minutes while developing a torque of 76 N-m.
Calculate: (a) Brake specific fuel consumption
(b) Brake mean effective pressure.
(c) Brake power.
(d) Specific power. [hp/cm2]
(e) Output per displacement. [hp/liter]
(f) Specific volume. [liter/hp]
10- A two stroke diesel engine was motored when the meter reading was
1.5 kW. Then the test on the engine was carried out for one hour and the
Following observations were recorded: Brake torque = 120 Nm; Speed =
600 rpm; Fuel used = 2.5 kg; calorific value of fuel = 40.3 MJ/kg;
Cooling water used = 818 kg; Rise in temperature of cooling water = 10°
Exhaust gas temperature = 345°C. Room temperature = 25°C; A/= 32: 1.
Determine:
(i) bp,
(ii) ip,
(iii) Mechanical efficiency,
(iv) Indicated thermal efficiency, and
(v) Draw heat balance sheet on minute basis and also in percentage
11- The following readings are taken during a test of a four-cylinder, two
stroke gasoline engine. Diameter = 10 cm, Stroke = 15 cm, Speed = 1700
rpms Area of positive loop of the indicator diagram = 5.75 sq.cm; Area of
the negative loop of the indicator diagram = 0.25 cm2; Length of
indicator diagram = 5.5 cm, Spring constant = 4.0 bar/cm. Find the
indicated power of the engine.
12- An 8-cylinder, four stroke engine of bore 10 cm and 9 cm stroke has a

compression ratio of 7 is 4500 rpm on a dynamometer which has 54 cm
arm. During a 10 minutes test the dynamometer scale beam reading was
48 kg and the engine consumed 4.4 kg of gasoline having a calorific
value of 44000 kJ/kg. Air at 27°C temperature and 1 bar pressure was
supplied to the carburetor at the rate of 6 kg/min.
Find (i) the brake power delivered (ii) The brake mean effective pressure,
(iii) The brake specific fuel consumption, (iv) The brake specific air
consumption, (v) The brake thermal efficiency, (vi) The volumetric
efficiency, (vii) The air-fuel ratio.
13- A gasoline engine working on 4-stroke develops a brake power of 22

kW. A Morse test was conducted on this engine and the brake power
(kW) obtained when each cylinder was made inoperative by short
circuiting. The spark plugs are 14.9, 14.3, 14.8 and 14.5 respectively. The
test was conducted at constant speed. Find the indicated power,
mechanical efficiency and bmep when all the cylinders are firing. The
bore of engine is 80 mm and stroke is 90 mm. The engine is running at
3000 rpm.
14- A 3.1-liter, four-cylinder, two-stroke cycle SI engine is mounted on
an electrical generator dynamometer. When the engine is running at 1200
RPM, output from the 220-volt DC generator is 54.2 amps. The generator
has an efficiency of 87%.
Calculate: (a) Power output of the engine .
(b) Engine torque.
(c) What is engine bmep?
15- Plot dimensionless piston position against crank angle for S/2L = 0.5,
0.4, 0.3, and 0.2.
16- Obtain expressions for the piston velocity and acceleration as a

function of the crank angle, constant angular velocity, and S/2L ratio. Use
a spreadsheet to calculate and plot velocity and acceleration against
crank angle for S/2L = 0.5, 0.4, 0.3, and 0.2.
17- A single-cylinder four-stroke-cycle spark-ignition engine operating at

3500 rpm has a brake mean effective pressure of 1800 kPa and a
displacement of 400 cm3. Atmospheric conditions are 101kPa and 27°C.
(a) If the stroke is 6 cm, what is the bore?
(b) What is the brake power?
(c) If the mass air-fuel ratio is 16 and the fuel flow rate is 0.00065
kg/s, what is the volumetric efficiency?
(d) Compare your results with the performance of a two-cylinder
engine with the same overall geometric characteristics.
18- A four-cylinder four-stroke-cycle spark-ignition engine with 200 cm3
displacement and operating in air at 27°C and 110 kPa has a friction
power of 27 kW and a brake power output of 136 kW at 3600 rpm.
(a) What is the mechanical efficiency?
(b) If it has a volumetric efficiency of 74% and burns liquid
Methanol with 15% excess air, what is the brake specific fuel
consumption?
19- A two-cylinder four-stroke-cycle engine produces 30 brake

horsepower at a brake thermal efficiency of 20% at 2600 rpm. The fuel is
methane burning in air with an equivalence ratio of 0.8 and a heating
value of 21,560 Btu/lbm. Ambient conditions are 520°R and 14.7 psia.
The engine mechanical efficiency is 88%, and the volumetric efficiency is
92%. What are the fuel flow rate, the displacement volume per cylinder,
and the brake specific fuel consumption? What is the bore if the bore and
stroke or equal?
20- A single-cylinder, two-stroke cycle model airplane engine with a
7.54-cm3 displacement produces 1.42 kW of brake power at 23,000 RPM
using glow plug ignition. The square engine (bore = stroke) uses 31.7
gm/min of castor oil-methanol-nitromethane fuel at an air-fuel ratio AF =
4.5. During intake scavenging, 65% of the incoming air-fuel mixture gets
trapped in the cylinder, while 35% of it is lost with the exhaust before the
exhaust port closes. Combustion efficiency = 0.94.
Calculate: (a) Brake specific fuel consumption.
(b) Average piston speed.
(c) Unburned fuel exhausted to atmosphere.
(d) Torque.
Design Problem:
21- Design a six-liter race car engine that operates on a four-stroke cycle.
Decide what the design speed will be, and then give the number of
cylinders, bore, stroke, piston rod length, average piston speed, imep,
brake torque, fuel used, AF, and brake power, all at design speed. All
parameter values should be within typical, reasonable values and should
be consistent with the other values. State what assumptions you make
(e.g., mechanical efficiency, volumetric efficiency, etc).
Good Luck
Prof. Dr. Saad A. El-Sayed

Fourth Year - Mechanical Power Eng. Dept. First Term - 2016/2017 Internal Combustion Engines

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Fourth Year – Mechanical Power Eng. Dept.

First Term – 2016/2017 Internal Combustion Engines

1- A 4-cylinder, 4-stroke has the following results on the test beds:

2- A 4-cylinder, 2-stroke has the following results on the test beds:

4- A 4- cylinder, 2-stroke diesel engine with 10.9 cm bore, 12.6 cm stroke

5- A 5-cylinder, 3.5 liter SIE operates on a 4-stroke cycle at 2500 r.p.m.

6-The observations recorded after the conduct of a retardation test on a

Find mechanical efficiency at half load.

7- A 1500-cm3, four-stroke cycle, four-cylinder CI engine, operating at

9- A single-cylinder, four-stroke cycle CI engine with 12.9-cm bore and

12- An 8-cylinder, four stroke engine of bore 10 cm and 9 cm stroke has a

13- A gasoline engine working on 4-stroke develops a brake power of 22

16- Obtain expressions for the piston velocity and acceleration as a

17- A single-cylinder four-stroke-cycle spark-ignition engine operating at

19- A two-cylinder four-stroke-cycle engine produces 30 brake

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