In order to achieve less cost of production, improve efficiency and power output, the important measurement and testing parameters are employed. These are a) friction power b) indicated power c) brake power d) fuel consumption e) air flow e) speed f) exhaust and coolant temperature g) emissions h) noise i) combustion phenomenon. The difference between the indicated and the brake power of an engine is defined as friction power, whereas air flow and emissions are related to combustion processes. There are only two internal losses, pumping losses and friction losses. During the inlet and exhaust stroke the gaseous pressure on the piston is greater on its forward side, hence during both strokes the piston must be moved against a gaseous pressure, and this causes pumping loss.

1. COLLEGEOFENGINEERINGROORKEE
-: Presentation on :-
METHOD OF TESTING OF I.C. ENGINE
SUBMITTED BY
MAYANK CHAUHAN
Mech. Deptt.
College of Engineering Roorkee

2. INTRODUCTION
 Engineperformance isan indication
of thedegreeof successof theengine
performs itsassigned task,
 theconversionof thechemical
energycontained in the fuel intothe
useful mechanical work.

3. The performanceof anengine is
evaluated on the
basisof the following;
 (a) Specific Fuel Consumption.
 (b) Brake Mean Effective Pressure.
 (c) Specific Power Output.
 (d) Specific Weight.
 (e) Exhaust Smokeand Other
Emissions.

4. BASIC MEASUREMENTS
 Thebasicmeasurementstobeundertakento
evaluatetheperformanceof anengineonalmost
all testsarethefollowing:
 (a) Speed
 (b) Fuelconsumption
 (c) Airconsumption
 (d) Smokedensity
 (e) Brake horse-power
 (f) Indicated horsepowerand friction horse
power
 (g) Heat balancesheetorperformanceof SI and
CI engine
 (h) Exhaustgasanalysis

5. MEASUREMENT OF SPEED
 Oneof the basic measurementsisthatof speed. A
widevarietyof speed measuringdevicesareavailable
in the market. Theyrangefroma mechanical
tachometertodigital and triggeredelectrical
tachometers.
 The bestmethodof measuring speed istocount
the numberof revolutionsinagiventime. Thisgives
anaccuratemeasurementof speed. Manyenginesare
fittedwithsuchrevolutioncounters.
 A mechanical tachometeroranelectrical
tachometercanalso beused formeasuring thespeed

6. FUEL CONSUMPTION MEASUREMENT
Fuelconsumptionismeasured intwo
ways:
 (a) Thefuel consumptionof anengine is
measured bydetermining thevolumeflow ina
given time interval and multiplying it by the
specificgravityof the fuel whichshould be
measured occasionallytogetanaccuratevalue.
 (b) Anothermethod is to measurethetime
required forconsumptionof agiven massof fuel

7. MEASUREMENT OF AIR
CONSUMPTION
 In ICengines, thesatisfactorymeasurementof air
consumption isquitedifficultbecausethe flow is
pulsating,duetothecyclicnatureof theengineand
becausetheairacompressiblefluid.
 Therefore, thesimple methodof using anorifice
in the inductionpipeis notsatisfactorysincethe
readingwill bepulsating and unreliable.
 Thevarious methodsand metersused forairflow
measurementinclude,
 (a) Airbox method,and
 (b) Viscous-flowairmeter

8. MEASUREMENT OF BRAKE
POWER
 The brakepower measurement involves the
determinationof the torqueand theangularspeed
of theengineoutputshaft. The torque measuring
device iscalled a dynamometer.
 Dynamometerscan be broadlyclassified into
two main types, powerabsorptiondynamometers
and transmissiondynamometer.

9. Absorption Dynamometers
 Thesedynamometersmeasureandabsorbthe
poweroutputof theenginetowhichtheyarecoupled.
Thepowerabsorbed isusuallydissipatedas heat by
some means. Exampleof suchdynamometersispony
brake, ropebrake, hydraulicdynamometer,etc.
Transmission Dynamometers
 In transmissiondynamometers, thepoweris
transmitted tothe load coupled totheengineafterit is
indicatedonsometypeof scale. Thesearealsocalled
torque-meters

10. PRONY BRAKE DYNAMOMETER
 Oneof thesimplestmethodsof measuring brake
power(output) istoattempttostoptheengineby
meansof a brakeontheflywheeland measurethe
weightwhichanarmattachedtothebrakewill
support,as ittriestorotatewiththeflywheel.
 Itconsistsof woodenblockmountedonaflexiblerope
orband thewoodenblockwhenpressed intocontact
withtherotatingdrumtakestheenginetorqueand
thepowerisdissipated in frictionalresistance. Spring
loaded boltsareprovidedtotightenthewoodenblock
and henceincreasethefriction.

11. MEASUREMENT OF FRICTION POWER
 Thedifferencebetween indicated powerand the brake
poweroutputof anengineisthefrictionpower.
 Almostinvariably, thedifferencebetweenagoodengine
and a badengineisduetodifferencebetweentheirfrictional
losses.
 Thefrictional lossesareultimatelydissipated tothe
cooling system(and exhaust)astheyappearintheform
of frictional heatand thisinfluencesthecoolingcapacity
required. Moreover, lowerfriction meansavailabilityof more
brakepower; hencebrakespecificfuelconsumptionis lower

12. MORSE TEST
 TheMorsetestisapplicableonlytomulticylinderengines.
 Inthistest,theengineisfirstrunattherequiredspeedand the
outputismeasured.
 Then,onecylinderiscutoutbyshortcircuitingthesparkPlugorby
disconnecting theinjectorasthecasemaybe.
 Inthistest,theengineisfirstrunattherequiredspeedand the
outputismeasured.
 Then,onecylinderiscutoutbyshortcircuitingthesparkplugorby
disconnecting theinjectorasthecasemaybe.

13. INDICATED POWER
 Thepowerdeveloped in thecylinderis known
as Indicated Horse Powerand isdesignatedasIP.
 The IPof anengineataparticularrunning
condition isobtained from the indicatordiagram.
 The indicatordiagram is the p-v diagramfor
onecycleat that load drawnwith the helpof
indicatorfitted on theengine. Theconstruction
and useof mechanical indicatorforobtaining p-v
diagram isalreadyexplain.

14. •
areas,thepositiveloopand negativeloop,aremeasuredwiththe
helpof aplani meterand letthesebeApand Ancm2 respectively,
thenetpositiveareais(Ap–An).
 h=(Ap-An)/Lincentimetre.
 Theheightmultipliedbyspring-strength(orspring number)
givestheindicated meaneffectivepressureof thecycle.
 Imep=(Ap-An)*S/L
 Pm=Ap*Sp/L-An*Sn/L
 Sp= Springstrengthused fortaking p-vdiagramof positive
loop, (N/m2percm)
 Sn= Springstrengthused fortaking p-vdiagramof negative
loop, (N/m2percm)
 Ap= AreainCm2of positivelooptakenwithspringof strength
Sp
 An= AreainCm2of positivelooptakenwithspringof strength
Sn
 IPdeveloped bytheengineisgivenby IP=PmLAn/L

15. FUEL CONSUMPTION
 Twoglassvesselsof 100ccand 200cccapacityare
connected in betweentheengineand main fuel tank
throughtwo, three-waycocks.Whenoneissupplying the
fuel totheengine, theotherisbeing filled.Thetimeforthe
consumptionof 100or200ccfuel ismeasuredwiththe
helpof stopwatch.
 Asmallglasstubeisattached tothemain fuel tankas
shown in figure.When fuel rateistobemeasured, the
valveisclosedsothatfuel isconsumed fromtheburette.
 Thetimefora knownvalueof fuelconsumptioncan be
measuredand fuelconsumptionratecan becalculated.
 Fuelconsumptionkg/hr= Xcc XSp.gravityof
fuel/1000xt

16. Friction Power
 Frictionpowerincludesthe frictional lossesand
thepumping losses. During suctionand exhaust
strokesthepiston must moveagainstagaseous
pressureand powerrequired todothis iscalled the
“pumping losses”.
 Thefriction loss is madeupof theenergy loss
dueto friction between thepistonand cylinderwalls,
pistonringsand cylinderwalls,and between the
crankshaftand camshaftand theirbearings,aswell
as by the loss incurred bydriving theessential
accessories,suchaswaterpump, ignitionunitetc.

17. Willan’s Line Method
 This method isalso knownas fuel rateextrapolation
method. In this methodagraphof fuelconsumption
(verticalaxis) versus brakepower(horizontalaxis) is
drawnand itisextrapolatedon the negativeaxisof brake
power.
 The interceptof the negativeaxisistakenas the
frictionpowerof theengineatthatspeed.
 Asshown in thefigure, in mostof thepowerrange
therelation betweenthe fuelconsumptionand brake
poweris linearwhenspeedof theengineis held constant
and thispermitsextrapolation. Furtherwhentheengine
does notdeveloppower, i.e. brakepower= 0,

18.  The maindraw back
of this method is the
long distanceto be
extrapolated fromdata
between 5 and 40 %
load towards
thezero lineof the fuel
input.
 Thedirectional
marginof errorisrather
wide becausethegraph
is notexactly linear

19. Heat balance sheet
 Theperformanceof anengineisusually
studied by heatbalance-sheet.Themain
componentsof the heatbalanceare:
 Heatequivalenttotheeffective(brake) workof
theengine,
 Heatrejected tothecooling medium,
 Heatcarried away from theenginewith the
exhaustgases, and
 Unaccounted losses.

20.  Theheatsupplied totheengineisonlyinthe
formof fuel-heatand thatisgivenby
 Qs = mf X CV
 valueof thefuel.
 Thevariousways inwhich heat isused up in the
system isgiven by
 (a) Heatequivalentof BP = kW = kJ/sec. = 0
kJ/min.
 (b) Heatcarriedaway bycoolingwater= Cpw X mw
(Two–Twi) kJ/min.
 Wheremw isthe massof coolingwaterin kg/minor
kg/seccirculated through thecooling.

21.  (c) Heatcarried away byexhaustgases =
mg Cpg (Tge –Ta) (kJ/min.)or(kJ/sec).
 Where mg is the massof exhaustgases
in kg/min.
 Tg = Temperatureof burntgases
coming outof the
engine.
 Ta = AmbientTemperature.
 Cpg = Sp. Heatof exhaustgases in
(kJ/kg-K)

22.  A partof heat is lost byconvectionand radiation
aswell adueto the leakageof gases. Partof the
powerdeveloped insidetheengineisalsoused to
run theaccessoriesas lubricating pump,camshaft
and watercirculating pump.
 Thesecannot be measured preciselyand sothis
is knownasunaccounted ‘losses’. Thisunaccounted
heatenergy iscalculated by thedifferentbetween
heatsupplied Qs and thesumof (a) + (b) (c).
 Theresultsof theabovecalculationsare
tabulated inatableand this table is knownas “Heat
BalanceSheet”.

23. Thank you.