# Ub8 Part 1.

## Presentation on theme: "Ub8 Part 1."— Presentation transcript:

 A cylinders displacement is the volume of the cylinder when the piston is at BDC.  It is the sum of the displacement of each cylinder.  It is defined as the volume of air/fuel mixture an engine can draw in.

Ex: 700 cc (cubic centimetres) 1000 cc = 1 Litre

Example : Vehicle has 4 cylinders : Each cylinder has a volume of 700cc : 700cc X 4 = 2800cc : 2800cc = 2.8 Litre

 Torque is the term used to describe a rotating force.  More torque generally means a car can accelerate faster  Torque is the actual reading of how “hard” and with how much “Force” the engine turns.

 Horsepower: 1 hp = 33,000 lb-ft / min  One horsepower is the ability to lift 33000 pounds one foot in one minute  The horsepower specification for an engine tells you how much power the engine can produce.  Horsepower is the rate at which the engine does work

Formula:  HORSEPOWER = (TORQUE * RPM) / 5252  A engine that makes 300 pound-feet of torque at 4,000 RPM produces  [(300 x 4,000) / 5,252] 228 horsepower at 4,000 RPM

 Think about:  Torque being how hard you can pound away on bicycle pedals  Horsepower being how fast you can spin the bicycle pedals.

 What is engine displacement?  What is horsepower?  What is Torque?  What are the different parts of an engine?

Spark plug Inlet valve Exhaust valve CylinderPiston The four-stroke engine

 Is a can-shaped part closely fitted inside the cylinder.  Piston rings consist of compression rings and oil rings.  Crankshaft takes the up-down motion of the piston and convertors it to a rotation motion  Connecting rod connects the piston to the crankshaft.

 The 4 Stroke engine cycle consist of these: 1) Intake 180degree 2) Compression 180 degree 3) Power/ Combustion 180 degree 4) Exhaust 180 degree  Total engine revolution 720 degree  One complete engine cycle consists of 4 engine strokes.

 The Intake Stroke consist of the piston travelling down.  Intake valves are open to allow Air/Fuel mixture to come into the combustion chamber.

 Intake plastic ducts  Intake manifolds

- Fuel injectors are electronically controlled valves that spray fuel to mix with air. - Creating that air fuel mixture -

 It is an electrical device that fits into the cylinder head and ignites air fuel mixtures.

Inlet valve open INTAKE STROKE The four-stroke engine Exhaust valve closed

Inlet valve open Piston down INTAKE STROKE The four-stroke engine Exhaust valve closed

Inlet valve open Piston down INTAKE STROKE The four-stroke engine Fuel in Exhaust valve closed

Inlet valve open Piston down INTAKE STROKE The four-stroke engine Fuel in Exhaust valve closed

 What is the purpose of the intake system?  What is the purpose of the spark plug?  What is the purpose of the fuel injector?  What is happening during the intake stroke?

 Compression stroke consist of the piston travelling back up.  Both intake and exhaust valves are closed  Air fuel mixture is now being compressed

Inlet valve closed COMPRESSION STROKE The four-stroke engine Piston up Exhaust valve closed

Inlet valve closed COMPRESSION STROKE The four-stroke engine Piston up Exhaust valve closed

Inlet valve closed COMPRESSION STROKE The four-stroke engine Piston up Exhaust valve closed

 The piston is now at the TDC  Spark plug ignites, creating a spark that ignites the compressed air fuel mixture.  Explosion is created and the piston is forced back down.  Hence the Power stroke  Both valves are still closed

Inlet valve closed POWER STROKE The four-stroke engine BANG Exhaust valve closed

Inlet valve closed POWER STROKE The four-stroke engine Piston down powerfully Exhaust valve closed

Inlet valve closed POWER STROKE The four-stroke engine Piston down powerfully Exhaust valve closed

Inlet valve closed POWER STROKE The four-stroke engine Exhaust valve closed

 Exhaust stroke the piston is travelling up  Exhaust valve is open  Intake valve is Closed  Exhaust gases being pushed out by piston

Inlet valve closed EXHAUST STROKE The four-stroke engine Exhaust valve closed

Inlet valve closed EXHAUST STROKE The four-stroke engine Exhaust valve open Piston up Exhaust gases out

Inlet valve closed EXHAUST STROKE The four-stroke engine Exhaust valve open Piston up Exhaust gases out

Inlet valve open INTAKE STROKE The four-stroke engine Exhaust valve closed

And so the cycle continues!!

 The exhaust system is needed to provide a pathway for exhaust fumes to be filtered and to reduce noise.  Exhaust manifold  Catalytic convertor  Muffler

- What is the purpose of the compression stroke and what is happening - What is the purpose of the power stroke and what is happening? - What is happening during the exhaust stroke?  What is the purpose of the exhaust system?

http://www.youtube.com/watch?v=IY WUWMmimjQ&feature=related http://videos.howstuffworks.com/aut o/car-parts-videos- playlist.htm#video-30374 Video of 4 Stroke cycle