The majority of the actual internal combustion engines, operating on different cycles have one common feature, combustion occurring in the cylinder after each compression, resulting in gas expansion that acts directly on the piston (work) and limited to 180 degrees of crankshaft angle.
According to its mechanical design, the six-stroke engine with external and internal combustion and double flow is similar to the actual internal reciprocating combustion engine. However, it differentiates itself entirely, due to its thermodynamic cycle and a modified cylinder head with two supplementary chambers: a combustion and an air heating chamber, both independent from the cylinder. Combustion, does not occur within the cylinder but in the supplementary combustion chamber, does not act immediately on the piston, and it's duration is independent from the 180 degrees of crankshaft rotation that occurs during the expansion of the combustion gases (work).
The combustion chamber is totally enclosed within the air-heating chamber. By heat exchange through the glowing combustion chamber walls, air pressure in the heating chamber increases and generate power for an a supplementary work stroke. Several advantages result from this, one very important being the increase in thermal efficiency. In the contemporary internal combustion engine, the necessary cooling of the combustion chamber walls generate important calorific losses.
The six-stroke engine has the following advantages:
    •    Thermal efficiency reaching 50%. (30% for the actual internal combustion engines)
    •    Fuel consumption reduced by more than 40%.
    •    Reduction of chemical, noise and thermal pollution.
    •    Two expansions (work) through six strokes.
    •    Direct injection and optimal fuel combustion at every engine speed.
    •    Multiple fuel, etc....
Cars equipped with the six-stroke engine will have fuel consumption and a polluting emissions significantly reduced.
With the six-stroke cycle, the two supplementary chambers allow parallel function from which results a full eight-event cycle: two four-event-each cycles, an external combustion cycle and an internal combustion cycle. The diagram shows the interconnection of the eight events in the six-stroke cycle. Event three and event six occur within closed chambers and have no direct action on the crankshaft. They are called static events compared to the six other dynamic events.
The first cycle of four events is of external combustion.
It includes 1. Event 1: pure air intake in the cylinder (dynamic event). 2. Event 2: pure air compression in the heating chamber (dynamic event). 3. Event 3: keeping pure air pressure in closed chamber where a maximum heat exchange occurs with the combustion chambers walls, without direct action on the crankshaft (static event). 4. Event 4: expansion of the super heated air in the cylinder, work (dynamic event). During this four event's cycle, the pure air never comes in direct contact with the heating source.
The second cycle of four events is of internal combustion.
It includes 1. Event 5: re-compressions of pure heated air in the combustion chamber (dynamic event). 2. Events 6: fuel injection and combustion in closed combustion chamber, without direct action on the crankshaft (static event). 3. Events 7: combustion gases expanding in the cylinder, work (dynamic event). 4. Event 8: combustion gases exhaust (dynamic event). During this four event, the air comes in direct contact with the heating source.
The sketch shows the cylinder head equipped with both chambers and four valves of which two are conventional (intake and exhaust). The two others are made of heavy-duty heat-resisting material. During the combustion and the air heating processes, the valves could open under the pressure within the chambers. To avoid this, a piston is installed on both valve shafts, which compensate this pressure. Being a six-stroke cycle, the camshaft speed is one third of the crankshaft speed.
The combustion chambers walls are glowing when the engine is running. Their small thickness allows heat exchange with the air-heating chamber, which is surrounding the combustion chamber. The air-heating chamber is isolated from the cylinder head to reduce thermal loss. (To make the engine presentation easier, the details of the chambers are not described on the cycle sketch).
Through heat transfer from the combustion chamber to the heating chamber, the work is distributed over two strokes, which results in less pressure on the piston and greater smoothness of operation. In addition, since the combustion chamber is isolated from the cylinder by it's valves, the moving parts, especially the piston, are not subject to any excessive stress from the very high temperatures and pressures. They are also protected from explosive combustion or auto-ignition, which are observed on ignition of the air-fuel mixture in conventional gas or diesel engines.
The combustion and air-heating chambers have different compression ratio. The compression ratio is high for the heating chamber, which operates on an external cycle and is supplied solely with pure air. On the other hand, the compression ratio is low for the combustion chamber, which operates on an internal combustion cycle.
The combustion of all injected fuel is insured, first, by the supply of preheated pure air in the combustion chamber, then, by the glowing walls of the chamber, which act as multiple spark plugs. In order to facilitate cold starts, the combustion chamber is fitted with a heater plug (glow plug).
In contrast to a diesel engine, which requires a heavy construction, this multi-fuel engine, which can also use diesel fuel, may be built in a much lighter fashion than that of a gas engine, especially in the case of all moving parts.
Injection and combustion take place in the closed combustion chamber, therefore at a constant volume, over 360 degrees of crankshaft angle. This feature gives plenty of time for the fuel to burn ideally, and release every potential calorie (first contribution to pollution reduction). The injection may be split up, with dual fuel using the SNDF system (Single Nozzle, Dual Fuel).
The glowing walls of the combustion chamber will calcine the residues, which are deposited there during fuel combustion (second contribution to pollution reduction).
As well as regulating the intake and exhaust strokes, the valves of the heating and the combustion chambers allow significant additional adjustments for improving efficiency and reducing noise.
Since new patents are being applied for, design details do not appear in the present description.
The following descriptions, charts and diagrams refer to the patented version of the Bajulaz cycle's principle. They are used to explain the six-stroke engine's functioning but they must not be taken as a final result. The development of the engine's prototype showed many improvements to be taken in consideration. For example, the piston-balanced valves depicted further were not used for the prototype, being replaced by a much more effective valve system, for which new patents are deposited.
    1.    The heat that is evacuated during the cooling of a conventional engine’s cylinder head is recovered in the six-stroke engine by the air-heating chamber surrounding the combustion chamber.
    1.    After intake, air is compressed in the heating chamber and heated through 720 degrees of crankshaft angle, 360 degrees of which in closed chamber (external combustion).
    1.    The transfer of heat from the very thin walls of the combustion chamber to the air heating chambers lowers the temperature and pressure of the gases on expansion and exhaust (internal combustion).
    2.    Better combustion and expansion of gases that take place over 540 degrees of crankshaft rotation, 360° of which is in closed combustion chamber, and 180° for expansion.
    3.    The glowing combustion chamber allows the optimal burning of any fuel and calcinate the residues.
    4.    Distribution of the work: two expansions (power strokes) over six strokes, or a third more than the in a four-stroke engine.
    5.    Better filling of the cylinder on the intake due to the lower temperature of the cylinder walls and the piston head.
    6.    Elimination of the exhaust gases crossing with fresh air on intake. In the six stroke-engine, intake takes place on the first stroke and exhaust on the fourth stroke.
    7.    Large reduction in cooling power. The water pump and fan outputs are reduced. Possibility to suppress the water cooler.
    8.    Less inertia due to the lightness of the moving parts.
    1.    Lower oil temperature. With combustion taking place in a closed chamber, the high temperatures less stress the oil and the risk of dilution is reduced, even in cold starts.
Since the six-stroke engine has a third less intake and exhaust than a four stroke engine, the depression on the piston during intake and the back pressure during exhaust are reduced by a third. The gain in efficiency balances out the losses due to the passage of air through the combustion chamber and heating chamber valves, during compression of fresh and superheated air.
Friction losses, theoretically higher in the six-stroke engine, are balanced by a better distribution of pressure on the moving parts due to the work being spread over two strokes and the elimination of the direct combustion.
Main advantages of the of the six-stroke engine.
Reduction in fuel consumption by at least 40%:
An operating efficiency of approximately 50%, hence the large reduction in specific consumption. The operating efficiency of current petrol engine is of the order of 30%. The specific power of the six-stroke engine will not be less than that of a four-stroke petrol engine, the increase in thermal efficiency compensating for the loss due to the two additional strokes.
Two expansions (work) in six strokes:
Since the work cycles occur on two strokes (360° out of 1080°) or 8% more than in a four-stroke engine (180° out of 720°), the torque is much more even. This leads to very smooth operation at low speed without any significant effects on consumption and the emission of pollutants, the combustion not being affected by the engine speed. These advantages are very important in improving the performance of car in town traffic.
Multifuel par excellence, it can use the most varied fuels, of any origin (fossil or vegetable), from diesel to L.P.G. or animal grease. The difference in inflammability or antiknock rating does not present any problem in combustion.
It’s light, standard petrol engine construction, and the low compression ratio of the combustion chamber, do not exclude the use of diesel fuel. Methanol-petrol mixture is also recommended.
Dramatic reduction in pollution:
Chemical, noise and thermal pollution are reduced, on the one hand, in proportion to the reduction in specific consumption, and on the other, through the engine’s own characteristics which will help to considerably lower HC, CO and NOX emissions. Furthermore, it’s ability to run with fuels of vegetable origin and weakly pollutant gases under optimum conditions, gives it qualities which will allow it to match up to the strictest standards.
Liquefied Petroleum Gas:
The great reduction in specific consumption should make the use of L.P.G. in monofuel attractive, due to the lower cost and much lower pollution emissions than those of petrol. In addition, with the same operating range, the volume occupied by the tanks will be equivalent to that of present tanks.
Cost comparable to those of a four-stroke engine:
The six-stroke engine does not require any basic modification to the existing engines. All technological experience and production methods remain unaltered.
The cost of the modification to the cylinder head (combustion chamber and heating chamber) is balanced by the simplification of several elements, particularly by the lightening of the moving parts, the reduction of the cooling system, the simplification of direct injection with no spark plug, etc. ... The reduction in the dimensions of the tank and it’s housing in a vehicle are also to be taken into consideration.
Billions of explosion engines are running worldwide at this time, and this era is not about to end. It is commercially obvious that the big market if for automobile, heavy goods, construction-site and farm vehicles. This is a priority for the six-stroke engine.
Drastically reducing fuel consumption and pollution without radically affecting performances would allow the current concept of the automobile to be reassessed.
There is, at this day, no wonder solution for the replacement of the internal combustion engine. Only improvements of the current technology can help it progress within reasonable time and financial limits. The six-stroke engine fits perfectly into this view. It’s adoption by the automobile industry would have a tremendous impact on the environment and world economy, assuming up to 40% reduction in fuel consumption and 60% to 90% in polluting emissions, depending on the type of fuel being used.
Fuel consumption for mid-sized cars should be within 4 and 5 liters per 100km. and 3 to 4 liters for the small-sized cars.
Automobiles equipped with the six-stroke engine could appear in the market within 3 to 5 years.
Other very attractive sectors, more rapidly accessible are:
Motorboats (inboard and outboard engines) might offer a big outlet for this type of engine. Their characteristics are perfectly suited to its use (economy, safety, simplification, and reduction in noise and pollution). Furthermore, the use of fuels other than gasoline would greatly reduce the risks of explosion.
Using non-fossil fuels of vegetable origin, natural gases and others, in simple, robust engine, operating with a minimum of adjustments and non-pollutant, would offer great advantages when provided for motor-pumps, generator sets, stationary engines, etc....intended for agriculture and industry.
Many more applications may also be envisaged.
Six-stroke engine  high level of efficiency (US Patent 4.809.511 & 4.513.568)