The six-stroke engine improves efficiency and reduces emissions by utilizing two power strokes, one from fuel and another from steam or air, resulting in a 40% increase in efficiency compared to traditional engines. Key designs include the Velozeta, Crower, and Bajulaz engines, which capitalize on waste heat to enhance performance. However, challenges such as higher initial costs, increased engine size, and complex designs remain significant drawbacks.

1. Topic: Six Stroke Engine

2. Introduction
• To improve Efficiency, Reduce Emission, Brake thermal efficiency,
Dramatic Reduction in pollution and Better Scavenging
• Six Stroke Engine have 2 power stroke - one by fuel, one by
steam/air
• Few notable six stroke engine Design in this class are:
1. The Velozeta six stroke engine Built by the College of Engineering at Trivendrum in India.
2. The Crower stroke engine, invented by bruce Crower of the U.S.A.
3. The Bajulaz engine by the Bajulaz S A Company of Switzerland.

3. DISADVANTAGE OF FOUR STROKE
ENGINE
There are many
losses in the
internal
combustion
engine as below:
1. Time loss(6%)
2. Heat
loss(12%)
3. Blow Down
loss(2%)
4. High Fuel
Consumption

4. APPROACHES IN SIX STROKE ENGINE
1. The engine captures the waste heat from the 4 stroke Otto cycle/Diesel
cycle & uses it to get additional power & exhaust stroke of the piston
in the same cylinder. Designs either use steam/air as the working fluid
for the additional power stroke. The additional stroke cools the engine
& removes the need for a cooling system making the engine lighter &
giving 40% increased efficiency over the normal Otto or Diesel Cycle.
These six stroke engines have 2 power strokes: one by fuel, one by
steam/air.
2. The six stroke engine uses a 2nd 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.

5. WORKING OF SIX STROKE ENGINE
Different working strokes of Six-Stroke Engine are as follows:
1. Suction Stroke
2. Compression Stroke
3. Combustion Stroke (1st Power Stroke)
4. Re-Compression Stoke(1st Exhaust Stroke)
5. Water/Air Injection (2nd Power Stroke)
6. 2nd Exhaust Stroke

6. MODIFICATION IN SIX STROKE ENGINE
• Crankshaft to Camshaft Ratio Modification
4-stroke engine, gear at crankshaft rotate 720◦ for 360◦ Camshaft to complete a cycle 6-
stroke engine, gear at the Crankshaft must rotate 1080◦ to rotate camshaft 360◦ &
complete cycle Their gear ratio is 3:1.
• Camshaft Modification
6-stroke engine 360◦ of cam is divided into 60◦. Exhaust cam has 2 lobes for to 2 exhaust
stroke (4th stroke & 6th stroke to push out steam).
• Cam follower modification
Bottom shape of regular follower has flat pattern, which is suitable with normal
camshaft for 4-stroke engine When reducing duration of valve opening from 9000 to only
6000 shape of follower must be changed from flat to roller/spherical shape.

7. ADVANTAGES OF THE SIX STROKE
ENGINE
1. Thermal efficiency reaching 50% (30% for the actual Internal combustion
engine).
2. Fuel consumption reduced by more than 40%.
3. Reduction of chemical, noise and thermal pollution up to 65%.
4. Two expansion (work) through six stroke.
5. Direct Injection and optimal fuel combustion at every engine speed.
6. We would get the better scavenging in fifth stroke
7. Lower engine temperature - easy to maintain the optimum engine
temperature level for better performance

8. DISADVANTAGES OF SIX STROKE ENGINE
1. High Initial cost Due to change in gear structure.
2. High Manufacturing cost in six stroke engine.
3. Engine size Increases Due to additional stroke in engine, fifth stroke
and sixth stroke.
4. Complex head design.
5. Complex cam design for exhaust (due to 2 exhaust strokes).
6. Thermodynamically the engine is stable, yet the designing of parts
becomes more and more complex as the torque requirement increases