1

BANGLADESH UNIVERSITY OF ENGINEERING & TECHNOLOGY

Course No.: ME 402

Course Title: INTERNAL COMBUSTION ENGINES SESSIONAL

Experiment No.: 4

Name of the Experiment:

PERFORMANCE TEST OF A PETROL ENGINE AT WIDE

OPEN THROTTLE (WOT) CONDITION

Date of Performance

2/05/2011

Name: Aashique Alam Rezwan

Student No.: 06 10 012

Date of Submission

16/05/2011

Section: “A” Group: A12

Dept: Mechanical Engineering

2

Experiment No.: 4

Name of the Experiment:

Performance Test of a Petrol Engine at Wide Open Throttle (WOT) Condition

Objectives:

The objectives of this experiment are as follows –

To test the performance of a Petrol Engine at WOT condition

To plot the performance curve of the Petrol Engine at WOT condition

o Bsfc vs. Bhp

o Exhaust Gas Temperature vs. Bhp

o Lubricating Oil Temperature vs. Bhp

Equipment/Apparatus:

The followings are used in this experiment:

1. Petrol Engine [Specifications are followed to next page]

2. Dynamometer

Type: Hydraulic

Torque Arm Length: 0.2386 m

3. Hydrometer

4. Wet Bulb Thermometer

5. Thermometer

6. Barometer [mbar]

7. Psychometric Chart

8. Petrol [Fuel]

9. Volume Meter

10. Stop Watch

11. Thermocouple [T-type]

12. Electric Battery [12V Top Terminal Battery]

13. Fuel & Water Tank

14. Tachometer [Type: Magnetic Induction]

15. Pressure Transducer [Wheatstone Bridge Resistance Transducer]

3

Engine Specifications & Ambient Data:

Brand Name NISSAN Lubrication Combine (Forced &

Splashed)

Model A12-A5M Cooling Water Cooled Date 2/5/2011

Engine No. S03789 Exhaust Flexible SS Tube Room Temp 30.5°C

Country of

Make JAPAN Lub Oil Filter Present Dynamometer

Hydraulic

Type

Manufacturer NISSAN

Co. Fuel Filter Present Dynamometer HP 120 HP

Rated Output 20 HP Air Cleaner Present BSFC (gm/bhp-hr)

Rated RPM 2400 Oil Pressure

Indicator Present Dry Bulb Temp 30.5°C

No. of

Cylinders 4 In-line Coupling Universal Atm. Pressure 991 mbar

Lub Oil Used SAE 30 Starting 12V Electric Battery Relative Humidity 0.73

Fuel Used Petrol Rotation CCW Correction Factors

(as per BS 5514)

α=0.957

Sp Gr 0.74 β=1.0065

Engine Loading Plan:

Rated Power = 20 hp Rated Speed = 2400 rpm Rated Load = 20 kg

Engine Performance Data:

Model: NISSAN A12-A5M No. S03789 hp: 20 RPM Control: Dynamometer

Dynamometer Shaft Revolution

Fuel Consumption Lab Condition BS Condition Temperature Torque

Indicator

Reading

Load W

(kg)

N

(rpm)

Amount

Collected

V

(ml)

Time of

Collection

t

(s)

Bhp P

(hp)

Bsfc

F (gm/bhp-

hr)

Bhp

Ps

(hp)

Bsfc

Fs (gm/bhp-

hr)

Lub Oil T1

(°C)

Exhaust Gas T2

(°C)

To

(kg-m)

128 15.36 3068 50 30.1 15.71 281.72 16.41 279.90 82 481 35.95

130 16.42 2902 50 31.2 15.88 268.78 16.60 267.05 88 473 38.43

133 18.03 2708 50 32.4 16.28 252.60 17.01 250.97 92 461 42.20

136 19.63 2515 50 33.6 16.46 240.90 17.20 239.34 93 446 45.95

137 20.16 2406 50 35 16.17 235.38 16.89 233.86 94 436 47.19

134 18.56 2190 50 37 13.55 265.71 14.16 263.99 95 416 43.44

131 16.96 1890 50 41 10.68 304.06 11.16 302.09 97 385 39.70

4

Graph:

200

220

240

260

280

300

320

10 11 12 13 14 15 16 17 18 19 20

Bsf

c

(gm

/bh

p-h

r)

Bhp

(hp)

Bsfc vs Bhp (BS CONDITION)

350

370

390

410

430

450

470

490

10 11 12 13 14 15 16 17 18 19 20

Exh

au

st G

as

Tem

per

atu

re

(°C

)

Bhp

(hp)

Exhaust Gas Temperature Vs Bhp

(BS Condition)

5

80

82

84

86

88

90

92

94

96

98

100

10 11 12 13 14 15 16 17 18 19 20

Lu

bri

cati

ng

Oil

Tem

per

atu

re

(°C

)

Bhp

(hp)

Lubricating Oil Temperature Vs Bhp

(BS Condition)

10

11

12

13

14

15

16

17

18

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

1500 2000 2500 3000 3500

Sh

aft

Ou

tpu

t

(hp

)

To

rqu

e

(kg

-m)

Speed

(rpm)

Performance Curve of the Engine

Torque Shaft Output Poly. (Torque) Poly. (Shaft Output)

6

Derating:

Rated (BS) Condition Lab Condition

Pr = 100 kPa Px = 99.1 kPa

Tr = 300 K Tx = 303.5 K

Φr = 0.6 Φx = 0.73

ηm = 0.85

BS 5514

References Formula/Relation/Coefficient Value

Annex-F φxPsx 3.185

Annex-E (Px – aφxPsx)/(Pr – aφrPsr) 0.98085

Annex-D (Tr/Tx)n, n = 0.75 0.9942

Formula – 3 K = (Px – aφxPsx)/(Pr – aφrPsr) (Tr/Tx)n 0.9742

Annex – C β 1.0065

Annex – B α 0.957

Where,

φxPsx = Water Vapour Pressure (kPa)

φ = Relative Humidity (%)

(Px – aφxPsx)/(Pr – aφrPsr) = Dry Air Pressure Ratio

Px = Barometric Pressure

K = Indicated Power

β = Fuel Consumption Recalculation Factor

α = Power Adjustment Factor

x = Denotes Lab Condition (Subscript)

r = Denotes Rated BS Condition (Subscript)

ηm = Mechanical Efficiency

n = Exponent

7

Sample Calculation:

Sample Calculation for Dynamometer Load = 18 kg

Shaft Revolution Speed, N = 2708 RPM

Power,

Brake Specific Fuel Consumption,

For Standard Condition,

Engine Power,

Brake Specific Fuel Consumption,

Assignments

i) Write short note on WOT.

Ans:

Wide open throttle (WOT) refers to an internal combustion engine's maximum intake of air

and fuel that occurs when the throttle plates inside the carburettor or throttle body are "wide

open", providing the least resistance to the incoming air. In the case of an automobile, WOT

is when the accelerator is depressed fully, sometimes referred to as "flooring it". This

condition occurs when the throttle plate is 50% or more open.

At high load or WOT operation, fuel is injected only during the intake stroke and maximum

thermal efficiency is obtained by operating with a homogeneous stoichiometric air-fuel

mixture. High levels of EGR are used at high load.

At WOT, manifold vacuum decreases. The higher manifold pressures in turn allow more air

molecules to enter the combustion cylinders, and thus additional molecules of fuel are

required to balance the combustion reaction. The additional molecules of air and fuel reacting

together produce more power.

ii) Compare performance under constant speed and WOT condition.

Ans:

At WOT condition, the power output capacity is increases as the speed increase, and become

maximum at maximum speed. The torque increases with the increase in speed and become

8

maximum at the rated speed. After the rated speed, as the speed increases the torque

decreases. At constant speed, only the load controls the output power. In both cases, the Bsfc

is minimum at rated speed and load condition.

Discussion:

In this experiment, we have experimentally tested a petrol engine at wide open throttle

condition. This test is performed under variable load condition. This engine can operate at

variable speed. The power capacity is maximum at maximum speed. In general, the engine

power increase as the amount of air volume sucked in the engine cylinder. This air flow is

controlled by the throttle valve in case of SI engine. The engine is tested under wide open

throttle condition. In WOT the throttle valve is open more than 50%. This ensures the

maximum air volume that can induced in the engine cylinder.

The load in the engine is provided by a hydraulic type dynamometer. The load in the test

setup is measured using a Wheatstone bridge type resistive pressure transducer, attach to the

dynamometer. As the engine load increases the engine speed decreases and reaches it rated

speed at the rated load. The engine speed is measured using a magnetic induction tachometer,

which changes the magnetic pulse each time a cut spot passes the static permanent magnet.

This magnetic pulse is then measured and calibrated for measuring the engine speed.

The performance curve of the engine found in this experiment is typical for an SI engine. The

torque increases as the speed increase and the maximum torque is obtained at the rated speed.

The output shaft power increases as the speed increases.

The cooling of engine is provided using water circulation around the cylinder casing in the

water jacket. The water circulation is in critical condition in the engine. The water leakage

due to the loose connection may cause the short circuit in the alternator used for generating

electrical power to ignite the spark and drive auxiliary equipment. In our case the leakage is

very much serious and no further experiment is possible. Immediate repairing is required for

the engine for further testing.

The exhaust gas temperature increases as the engine speed increased but the lubricating oil

temperature falls with increasing engine speed. As the engine speed increased the power

generated by burning the fuel is also increased. So the heat generated inside the engine

cylinder also increased. Thus the exhaust temperature increased with increasing engine speed.

The lubricating oil circulation increased with increasing speed. Thus the lubricating oil

temperature drops with engine speed.