seminar topic report fuck

2. CONTENTS
 Introduction to Engines
 Types of Engine
 Construction of HEMI Engines
 Different Types Of Engines
 Parts Of Hemi Engine
 Working of HEMI Engines
 Comparison between HEMI and Flathead Engine
 Benefits and Drawbacks

3. Introduction
 Hemi Heads require a more complex valvetrain,
including a "Double Rocker" system which uses two
rocker shafts per head.
 The extra parts, complexity and flexibility tend to limit
RPMs. Adding to the cost of production, the piston
castings are more complex as well.
 With the hemispherical combustion chamber design,
the intake and exhaust valves are usually on opposite
sides of the chamber, allowing for the combustion
mixture to flow directly across the chamber, commonly
referred to as "cross-flow" heads.

4. Types of Engines
 4 Stroke
 Flat Head
 V
 Hemi
 2 stroke engine
 Flat
 Rotary
 Rocket
 Diesel
 2 stroke
 4 stroke
 Jet or Turbine

7. Different types Of Hemi Engines

9. 5.7-liter HEMI Magnum V-8 engine

10. Parts Of Hemi Engine
Cylinder
 The core of the engine is the cylinder. The piston
moves up and down inside the cylinder. The engine
described here has one cylinder. That is typical of
most lawn mowers, but most cars have more than
one cylinder (four, six and eight cylinders are
common). In a multi-cylinder engine the cylinders
usually are arranged in one of three ways: inline, V
or flat (also known as horizontally opposed or
boxer).

11. Spark Plug
 The spark plug supplies the spark that ignites the
air/fuel mixture so that combustion can occur. The
spark must happen at just the right moment for things
to work properly.
Valves
 The intake and exhaust valves open at the proper time
to let in air and fuel and to let out exhaust. Note that
both valves are closed during compression and
combustion so that the combustion chamber is sealed.

12. Piston
 A piston is a cylindrical piece of metal that moves up
and down inside the cylinder.
Piston ring
 Piston rings provide a sliding seal between the outer edge
of the piston and the inner edge of the cylinder. The rings
serve two purposes:
 They prevent the fuel/air mixture and exhaust in the
combustion chamber from leaking into the sump during
compression and combustion.
 They keep oil in the sump from leaking into the
combustion area, where it would be burned and lost.

13. Combustion Chamber
 The combustion chamber is the area where
compression and combustion take place. As the
piston moves up and down, you can see that the
size of the combustion chamber changes. It has
some maximum volume as well as a minimum
volume. The difference between the maximum and
minimum is called the displacement and is
measured in liters or CCs (Cubic Centimeters,
where 1,000 cubic centimeters equals a liter).

14. Connecting Rod
 The connecting rod connects the piston to the
crankshaft. It can rotate at both ends so that its angle
can change as the piston moves and the crankshaft
rotates.
Exhaust
 Once the piston hits the bottom of its stroke, the
exhaust valve opens and the exhaust leaves the
cylinder to go out the tail pipe.

15. Sump
 The sump surrounds the crankshaft. It contains some
amount of oil, which collects in the bottom of the
sump (the oil pan).
Compression
 Then the piston moves back up to compress this
fuel/air mixture. Compression makes the explosion
more powerful.

16. Intake Stroke
 The piston starts at the top, the intake valve opens, and
the piston moves down to let the engine take in a
cylinder-full of air and gasoline. This is the intake
stroke. Only the tiniest drop of gasoline needs to be
mixed into the air for this to work.
Combustion
 When the piston reaches the top of its stroke, the
spark plug emits a spark to ignite the gasoline. The
gasoline charge in the cylinder explodes, driving the
piston down

17. Crankshaft
The crank shaft turns the piston's up and down motion into circular
motion just like a crank on a jack-in-the-box does.

18. Working Of Hemi Engine
 Working of HEMI Engine is based on Otto cycle which consist of the
following strokes. A stroke refers to the full travel of the piston from
Top Dead Center (TDC) to Bottom Dead Center (BDC).
 1.Intake Stroke:-On the intake or induction stroke of the piston , the
piston descends from the top 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 the cylinder
through the intake port. The intake valve(s) then close.
 2.Compression stroke:-With both intake and exhaust valves closed, the
piston returns to the top of the cylinder compressing the fuel-air
mixture. This is known as the compression stroke.

19. 3.Power stroke:-While the piston is close to Top Dead Center, the
compressed air–fuel mixture is ignited, usually by a spark plug (for a
gasoline or Otto cycle engine) or by the heat and pressure of
compression (for a diesel cycle or compression ignition engine). The
resulting massive pressure from the combustion of the compressed
fuel-air mixture drives the piston back down toward bottom dead
center with tremendous force. This is known as the power stroke,
which is the main source of the engine's torque and power.
4.Exhaust stroke:-During the exhaust stroke, the piston once again
returns to top dead center while the exhaust valve is open. This action
evacuates the products of combustion from the cylinder by pushing the
spent fuel-air mixture through the exhaust valve(s).

20. The intake (A) stroke is
performed by an isobaric
expansion, followed by the
compression (B) stroke,
performed by an adiabatic
compression. Through the
combustion of fuel an
isochoric process is
produced, followed by an
adiabatic expansion,
characterizing the power (C)
stroke. The cycle is closed by
an isochoric process and an
isobaric compression,
characterizing the exhaust
(D) stroke.
OTTO CYCLE
The Otto cycle p-V diagram

21. COMPARISON BETWEEN HEMI AND
FLATHEAD ENGINE
• In a HEMI engine, the top of the
combustion chamber is
hemispherical, as seen in the
image above
• In a Flathead engine, the top of
the combustion chamber is flat,
as seen in image above
• The intake and exhaust valves
are usually on opposite sides of
the chamber
• The valves are in the block,
rather than in the head, and
they open in a chamber beside
the piston

22. • Thermal efficiency in HEMI
engine is extremely good
• Thermal efficiency in flathead
engine is poor
• HEMI engines are costly
engines
• Flathead engines are cheap
engines

23. Benefits and drawbacks
 Although a wedge-head design offers simplified valve
actuation, it usually requires the air/fuel mixture to
make sharp turns en route to and from the chamber.
 With a hemispherical chamber, larger valves are possible
and a straighter, less restrictive flow path can be
provided for the air/fuel mixture.
 This improves engine breathing. Placing the spark plug
near the center of the chamber aids in achieving
complete combustion of the fuel/air mixture, though it
is not mandatory.