A six stroke engine captures waste heat from the four stroke cycle to power an additional power and exhaust stroke. Designs use steam or air for the extra stroke, improving efficiency by 40% over four stroke engines. There are two types - single piston designs that add a steam/air stroke, and opposed piston designs that replace valves with a second piston. The additional stroke cools the engine, reducing weight and complexity versus four stroke designs by eliminating the cooling system. Six stroke engines provide increased torque by 35% and efficiency through two power strokes per cycle.

1. Guided by :- Prof. Gajanan Thokal
Presented by :- Chetan Pawar (PIIT,NEW PANVEL)

2. History
Introduction
Classification
Modifications Suggested For Engine
Parts
Working Principles
Comparison Of Six Stroke Engine With
Four Stroke Engine
Graphs
Thermodynamic Advantages
Limitations
Conclusion
TOPICS TO DISCUSS

3. HISTORY
The term six stroke engine describes two different approaches in the
internal combustion engine, developed since the 1990s,to improve its
efficiency and reduce emissions.
In the first approach, the engine captures the waste heat from the four
stroke Otto cycle or Diesel cycle and uses it to get an additional power
and exhaust stroke of the piston in the same cylinder.
Designs either use steam or air as the working fluid for the additional
power stroke.

4. In the first approach, the engine captures the waste heat from the four
stroke Otto cycle or Diesel cycle and uses it to get an additional power and
exhaust stroke of the piston in the same cylinder. Designs either use steam or
air as the working fluid for the additional power stroke.
As well as extracting power, the additional stroke cools the engine and
removes the need for a cooling system making the engine lighter and giving
40% increased efficiency over the normal Otto or Diesel Cycle.
The pistons in this six stroke engine go up and down six times for each
injection of fuel. These six stroke engines have 2 power strokes: one by fuel,
one by steam or air.
INTRODUCTION

5. The currently notable six stroke engine designs in this class are
the Crower's six stroke engine , invented by Bruce Crower of the
U.S.A; the Bajulaz engine by the Bajulaz S A company, of
Switzerland; and the Velozeta’s Six-stroke engine built by the
College of Engineering, at Trivandrum in India.
The second approach to the six stroke engine uses a second
opposed piston in each cylinder which moves at half the cyclical
rate of the main piston, thus giving six piston movements per cycle.
Functionally, the second piston replaces the valve mechanism of a
conventional engine and also it increases the compression ratio. The
currently notable six stroke engine designs in this class include two
designs developed independently: the Beare Head engine, invented
by Australian farmer Malcolm Beare, and the German Charge pump,
invented by Helmut Kottmann

6. Single piston designs -
Griffin six stroke engine
Bajulaz six stroke engine
Crower six stroke engine
Velozeta six stroke engine
Opposed piston design -
Beare head
M4+2
Piston charger engine

7. MODIFICATIONS SUGGESTED FOR
ENGINE PARTS
Cam shaft / Crank shaft Sprockets
Cam lobes
Valve Timing
Secondary Air Induction System

8. A six stroke engine describes a number of different approaches
in the internal combustion engine to capture the waste heat from
the four stroke Otto cycle and use it to power an additional power
and exhaust stroke of the piston.
Designs either use steam or air as the working fluid for the
additional power stroke. As well as extracting power, the
additional stroke cools the engine and removes the need for a
cooling system making the engine lighter and giving 40%
increased efficiency over the Otto Cycle.

9. During the first stroke
the inlet valve opens and
air-fuel mixture from
carburetor is sucked into
the cylinder through the
inlet manifold .

10. During the second
stroke, piston moves
from BDC to TDC,
both the inlet valve and
exhaust valve are
closed and the air-fuel
mixture is compressed.

11. During the third stroke,
power is obtained from
the engine by igniting the
Compressed air- fuel
mixture using a spark
plug. Both valves remain
closed. Piston moves from
TDC to BDC.

12. During the fourth stroke,
exhaust the valve and the
reed valve opens to
remove the burned gases
from the engine cylinder.
Piston moves from BDC to
TDC.

13. During the fifth stroke, the
exhaust valve remains open and
the reed valve closes. Fresh air
from the air filter enters the
cylinder through the secondary
air induction line provided at
the exhaust manifold . The reed
valve opens.

14. During the sixth stroke, the
exhaust valve remains open. The
air sucked into the cylinder
during the fifth stroke is
removed to the atmosphere
through the exhaust manifold.
The reed valve opens and the
reed valve closes.

15. 1. In a six stroke engine the energy absorption is less because
of slower acceleration of reciprocating parts.
2. It reduces the weight and complexity of the engines head
by as much as 50%. Instead of using energy to drive the
head.
3. Torque is increased by 35% and efficiency increased by
the same.
4. Increased torque and power output.
COMPARISON OF SIX STROKE ENGINE
WITH FOUR STROKE ENGINE

17. GRAPHS

21. The intake begins at 0 degrees on the X-axis. The effect of
the additional volume changes that the upper piston has on
the volume of the engine is all positive from a
thermodynamic point of view. If the engine were a normal 4
stroke the cylinder capacity would be 340cc Of note -
maximum volume at the end of the intake stroke occurs at
173 degrees instead of 180 degrees- the change in volume is
308cc which is less than a 4 stroke (340cc)- yet the total
volume at the end of the intake stroke is 415cc as opposed to
375cc for a conventional stroke.
The change in volume during the compression stroke is
slightly greater than a 4 stroke after the ports are closed.

22. The expansion stroke is much greater than a 4 stroke,
both from T.D.C. to B.D.C. and from T.D.C. till the
exhaust port is open.
It is possible to leave the opening of the exhaust port
later than in a 4 stroke because maximum volume is
not reached until after B.D.C.-548 deg. Instead of 540
deg .
Hence the 6 stroke system is better from a
thermodynamic point of view because more energy is
extracted from the expansion process.

23. During the critical combustion period the rate of change in
volume in the 6 stroke is less than a 4 stroke. Minimum
volume is not reached until after T.D.C., at 361 deg. This is
because of the phasing of the upper piston. It is retarded in
reaching its T.D.C. until 20 deg. after T. D.C. (380). This is
much better from a thermodynamic view in that combustion
occurs at a more constant volume; hence ignition timing is
not as critical as in a 4 stroke. There is room in the
combustion chamber for up to 4 spark plugs and two direct
injectors if needed.

24. Injecting relatively cold water onto a hot metal piston can
damage it over time from thermal expansion and contraction.
Separate water tank would have significant weight and space
penalties.
A steam-free cool down reduces the temperature inside the
combustion chamber.
Cold climate anti-freezing measures would be needed in the
water reservoir.

25. In a six stroke engine the energy absorption is less because
of slower acceleration of reciprocating parts The piston
speed of the upper piston is about a quarter of the main
piston; therefore its service life should be at least twice that
of the main piston.
In the Beare design, per single cylinder, the number of parts
is 15 compared to a four stroke of approx 40 to 50 parts.
Also, to reduce manufacturing costs the head and block can
be machined in one piece.
The bottom piston is a standard design and the Beare Head
bolts directly onto the engine block, replacing the overhead
valves and standard head.

26. It reduces the weight and complexity of the engines head by
as much as 50%. Instead of using energy to drive the head,
the head actually develops energy for conversion to power
back through the timing chains of an engine.
Torque is increased by 35% and efficiency increased by the
same. This can be achieved by simply unbolting an existing
head of a four-stroke engine and then bolting on a Beare
Head.
Increased torque and power output.
Better fuel economy and cleaner burning longer service
intervals and considerably reduced tooling costs when
compared with a conventional four-stroke design.