Team Nozzle

8/3/2019 Team Nozzle

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TEAM NOZZLE

PRESENT….

FOUR STROKE

PETROL

ENGINE



INTRODUCTION



• Today, internal combustion

engines in cars, trucks, motorcycles, airc

raft, construction machinery and manyothers, most commonly use a four-stroke

cycle.

• The four strokes refer to intake,

compression, combustion (power), and

exhaust strokes that occur during two

crankshaft rotations per working cycle of

the gasoline engine and diesel engine



• cycle begins at Top Dead Center (TDC),when the piston is farthest away from the

axis of the crankshaft.

• A stroke refers to the full travel of the

piston from Top Dead Center (TDC) toBottom Dead Center (BDC)



Component of 4 stroke

engine



Exhaustcamshaft

Spark plugInlet

Camshaft

ValveRed-exhaustBlue- intake

Piston

Connectingrod

Crankshaft

Cooling

water duct



4 STROKE CYCLE

1. INTAKE STROKE

2. COMPRESSION STROKE

3. POWER STROKE

4. EXHAUST STROKE



Intake Stroke

- the piston descends from thetop of the cylinder to the

bottom of the cylinder,

reducing the pressure inside

the cylinder.

- A mixture of fuel and air is

forced by atmospheric (or

greater) pressure into thecylinder through the intake

port.

- The intake valve then close.



Compression Stroke

• With both intake and exhaustvalves closed, the pistonreturns to the top of thecylinder compressing the fuel-air mixture.

• This is known asthe compression stroke.



Power Stroke

• While the piston is close to TopDead Center, the compressed air –fuel mixture is ignited, usually bya spark plug

• The resulting massive pressure

from the combustion of thecompressed fuel-air mixture drivesthe piston back down towardbottom dead center withtremendous force.

• This is known as the power stroke,which is the main source of theengine's torque and power.



Exhaust Stroke

• the piston once again returns totop dead center while the exhaustvalve is open.

• This action evacuates theproducts of combustion from thecylinder by pushing the spent fuel-air mixture through the exhaustvalve



HANDLING AND OPERATION

PRINCIPLE OF 4 STROKE PETROL

ENGINE



• A four-stroke petrol engine performs all thefour operations which is suction

(induction), compression, expansion(power) and exhaust in four strokes of thepiston in two revolutions ofthe crankshaft

• The petrol engines take in a flammablemixture of air and petrol, which is ignited

by a timed spark when the charge iscompressed.



ADVANTAGES OF 4 STROKE

PETROL ENGINE



Compare to 2 stroke engine, 4 stroke

petrol engine is;

1. More economy

2. More torque3. More durability

4. Cleaner emissions



Fuel Economy

• 2-strokes tend to get worse fuel economythan four strokes is that they pull air inthrough the intake port whilesimultaneously pushing used gases out

through the exhaust port

• 4-Stroke engines have a dedicated intake,power and exhaust stroke, which keepsfuel-to-exhaust crossover to a minimum



More Torque

• 4-stroke engines almost always makemore torque at low RPM than 2-strokes

• 4-stroke uses almost all of its fuel to impartpower to the crankshaft



More Durability

• 2-strokes must rev to very high RPM tomake any power, most applications usingthem are geared toward maintaining that

RPM



Cleaner Emissions

• 2-strokes tend to run very dirty.

• 2-stroke engines require that oil be injectedwith the fuel in order to lubricate the

crankcase

• 4-Stroke engines have a dedicated oilingsystem that's kept largely separate from the

combustion chamber, which help to ensurethat the only thing burning in the engine isgasoline.



Disadvantages of the 4 stroke

petrol engine



- More complex and harder to troubleshoot- Require oil to be changed regularly

- More expensive than 2 stroke



Fuel injection circuit for EFI

engine

EFI = ELECTRONIC FUEL INJECTION



HOW EFI WORK???

• EFI system can divided

into 3;

a) Delivery system

b) Air induction systemc) Electronic control

system



The Fuel Delivery System



The Air Induction System



Electronic Control System



Basic System Operation



Factor that cause detonation

in an internal combustionengine



Following are the main factors, which affects detonation,

• The fuel used in internal combustion engine will considerably

effects on the chances of detonation. Alcohol and benzol do notcause detonation but it can not be use due its low calorific valueand other objections to use as fuel. Again alcohol cannot blendwith petrol in the presence of water.

•

The detonation is also promoted by increase incompression ratio. The compression ratio at which detonation just occurs is known as the Highest Useful Compression Ratio.Higher the compression ratio higher the chances of detonationand lower the output.

• If the carbon deposits are in the cylinder and used excessivesparking temperature, the detonation will increased rapidly.



• The position of the spark plug in a combustion chamberdetermines the distance the flame has to travel in order to

reach the detonation zone. More the distance more thechances of detonation. A centrally placed spark plug worksbetter. Spark plug must be placed near to exhaust valvebut the exhaust must be located away from detonatingzone.

• Higher temperature of the walls of combustion chambertends to raise the temperature combustion chambertending to raise thetemperature of Detonation zone.

• The rate at which the combustion of the portion of the fuel,which is first to ignite immediately after the application ofthe spark, also affects detonation.



The end..

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