Thermodynamics LabThermodynamics LabGroup 2Group 2Krishna, Rafsan, Mostafa, Omari, Rohan, Krishna, Rafsan, Mostafa, Omari, Rohan, MaheshMahesh

Closing Fuel entryClosing Fuel entryImportant because it will prevent more fuel leaking into Important because it will prevent more fuel leaking into the carburettor. Not completely safe as some fuel is the carburettor. Not completely safe as some fuel is already insidealready inside

Engine checkEngine checkMaking sure that it is in the off positionMaking sure that it is in the off position

Drain the oilDrain the oil

Remove air filterRemove air filterThe filter removes particles from the air The filter removes particles from the air before it flows down into the engine.before it flows down into the engine.

AirAirFlowFlow

Remove Exhaust Remove Exhaust ManifoldManifoldThis helps reduce engine noiseThis helps reduce engine noiseIt much shorter than one found in a car and does not have a catalytic converterIt much shorter than one found in a car and does not have a catalytic converterThe small hole is allows condensed water from the exhaust emissions to escapeThe small hole is allows condensed water from the exhaust emissions to escape

Remove Spark plugRemove Spark plugThis ignites the air fuel mixture inside the This ignites the air fuel mixture inside the pistonpiston

Remove rocker coverRemove rocker cover

RockersRockersThese are operated by the pushrods and control the valve positionsThese are operated by the pushrods and control the valve positionsThe breather tube returns unused fuel to the inlet to improve The breather tube returns unused fuel to the inlet to improve efficiencyefficiency

Remove air intake Remove air intake mountmount

ChokeChokeControls air flow into engineControls air flow into engineOpen for cold starts so a richer mixture is usedOpen for cold starts so a richer mixture is usedClosed when engine is hot so fuel is used at a more efficient ratioClosed when engine is hot so fuel is used at a more efficient ratio

ThrottleThrottleConcerned with power production; Concerned with power production; regulates the input of the air-fuel mixtureregulates the input of the air-fuel mixture

Remove side coverRemove side cover

FanFanThe solenoid magnet creates the current for the spark plug by magnetic induction The solenoid magnet creates the current for the spark plug by magnetic induction so no need for battery. Cord for initial startso no need for battery. Cord for initial startNot convenient for large vehicles because large start force neededNot convenient for large vehicles because large start force neededThere are 2 sparks per cycle, on the 2nd and 4th stroke, the 2nd spark is ‘wasted’There are 2 sparks per cycle, on the 2nd and 4th stroke, the 2nd spark is ‘wasted’

Engine CoolingEngine CoolingAir is used for cooling and is sucked in by the fan. The cover is Air is used for cooling and is sucked in by the fan. The cover is important because when it is started by hand, the grooves on the fan important because when it is started by hand, the grooves on the fan and cover connect and therefore the cord can spin the magnet and fan.and cover connect and therefore the cord can spin the magnet and fan.

Engine CoolingEngine CoolingCar engines are cooled by water, which is good because Car engines are cooled by water, which is good because it has a much higher specific heat capacity however it is it has a much higher specific heat capacity however it is much heavier and would require a radiator as well.much heavier and would require a radiator as well.

CarburettorCarburettorChoke restricts air but throttle regulates the mixture for power control.Choke restricts air but throttle regulates the mixture for power control.Fuel is sucked in from the tank by a pressure difference.Fuel is sucked in from the tank by a pressure difference.Now cars have pumps because it is more controlled, more efficient and there Now cars have pumps because it is more controlled, more efficient and there are lower maintenance costs.are lower maintenance costs.

Air + fuelAir + fuelmixed heremixed here

Inside the crank caseInside the crank caseThe diameter ratio is 1:2 so that the cam shaft rotates once The diameter ratio is 1:2 so that the cam shaft rotates once when the crank shaft rotates twicewhen the crank shaft rotates twiceA small hook splashes oil as the crank shift spins, for lubricationA small hook splashes oil as the crank shift spins, for lubrication

Crank ShaftCrank ShaftCam shaftCam shaft

Cylinder HeadCylinder HeadThe small cavity seen is for the The small cavity seen is for the compressed gasescompressed gases

Timing MarksTiming MarksThese allow the cam and crank shaft to be aligned These allow the cam and crank shaft to be aligned properly so the different strokes occur at the correct properly so the different strokes occur at the correct momentsmoments

Piston ringsPiston ringsThese expand and form a seal inside the cylinder to prevent the oil and These expand and form a seal inside the cylinder to prevent the oil and the fuel mixture from escaping. The second ring seen here is to scrape the fuel mixture from escaping. The second ring seen here is to scrape the oil back. They receive the most wear because they are in contact the oil back. They receive the most wear because they are in contact with the cylinder walls.with the cylinder walls.

PushrodsPushrodsThey push the rocker which pushes the valves.They push the rocker which pushes the valves.They are not present in cars because they have overhead cams which push the valves They are not present in cars because they have overhead cams which push the valves directly. This is because car engines run at high speeds and the rods are liable to bending. directly. This is because car engines run at high speeds and the rods are liable to bending. The valves open once each out of synchronisation to prevent the mixture exiting as it entersThe valves open once each out of synchronisation to prevent the mixture exiting as it enters

Cam shaftCam shaftHere there is a spring and weight assembly which makes hand starting the engine Here there is a spring and weight assembly which makes hand starting the engine easier by opening the exhaust valve slightly. This helps because the compression easier by opening the exhaust valve slightly. This helps because the compression stroke is difficult by hand and this reduces the pressure. However, as the engine stroke is difficult by hand and this reduces the pressure. However, as the engine starts and the cam shaft begins to spin quickly, the spring no longer has an effect.starts and the cam shaft begins to spin quickly, the spring no longer has an effect.

We then rebuilt it We then rebuilt it SuccessfullySuccessfullyYou guys can add stuff here about the rebuild, a few You guys can add stuff here about the rebuild, a few pics with a title. - I have done all the questionspics with a title. - I have done all the questions

Team 2Team 2