Russell BOURKE

2-Cycle Engine

The Bourke Engine was designed by Russell Bourke in the 1920s, as an improved two stroke engine. Despite finishing his design and building several working engines, the onset of World War II, lack of test results,[1] and the poor health of his wife compounded to prevent his engine from ever coming successfully to market. The main claimed virtues of the design are that it has only two moving parts, is light weight, powerful, has two power pulses per revolution, and does not need oil mixed into the fuel.


The Bourke engine is basically a two stroke design, with two horizontally opposed pistons that move in the same direction at the same time, so that their operations are 180 degrees out of phase. The pistons are connected to a Scotch Yoke mechanism in place of the more usual crankshaft mechanism, which reduces the acceleration of the pistons, slightly. The incoming charge is compressed in a chamber under the pistons, as in conventional crankcase charged two strokes. Unlike them the chamber is sealed from the crankcase.


The operating cycle is very similar to that of a current production spark ignition two-stroke with crankcase compression, with three modifications.

Firstly, the fuel is injected directly into the air as it moves through the transfer port.

Secondly the engine is designed to run without using spark ignition once it is warmed up. This known as auto-ignition or dieseling, and the air/fuel mixture starts to burn due to the high temperature of the compressed gas, and/or the presence of hot metal in the combustion chamber.

Thirdly, it is claimed that the piston stops at Top Dead Centre for hydrogen detonation and/or complete combustion of the fuel.

Design Features

The following design features have been identified

Mechanical Features

Scotch yoke instead of connecting rods to translate linear motion to rotary motion

Fewer moving parts (only 2 moving assemblies per opposed cylinder pair) and the opposed cylinders are combinable to make 2, 4, 6, 8, 10, 12 or any even number of cylinders

Smoother operation due to elimination of crank and slider mechanism

The piston is connected to the Scotch yoke through a slipper bearing (a type of hydrodynamic tilting-pad fluid bearing)

Mechanical fuel injection.

Ports rather than valves.

Easy maintenance (top-overhauling) with simple tools.

The Scotch yoke does not create lateral forces on the piston, reducing friction, vibration and piston wear.

O-rings are used to seal joints rather than gaskets.

The use of the Scotch Yoke reduces vibration from the motions of the connecting rod — for example, the peak acceleration in a Scotch yoke is 25% less than the acceleration in a conventional crank and slider arrangement.

The Scotch Yoke makes the pistons dwell very slightly longer at top dead center, so the fuel burns more completely in a smaller volume.

Gas Flow and Thermodynamic Features

Low exhaust temperature (below that of boiling water) so metal exhaust components are not required, plastic ones can be used if strength is not required from exhaust system

Extremely fast hydrogen detonation burn time of the lean mixture so the engine can be considered to be a hydrogen detonation or hydrogen "explosion" engine.

15:1 to 24:1 compression ratio for high efficiency and it can be easily changed as required by different fuels and operation requirements.

Fuel is vaporised when it is injected into the transfer ports, and the turbulence in the intake manifolds and the piston shape above the rings stratifies the fuel air mixture into the combustion chamber.

Lean burn for increased efficiency and reduced emissions.

Fuel can be injected very late into the transfer port. This will reduce the amount of fuel that is blown straight out of the exhaust port, for a given scavenge ratio[citation needed]. This will increase efficiency and reduce HC emissions.


This design uses oil seals to prevent the combustion chamber created pollution's piston ring blow-by from polluting the crankcase oil extending the life of the oil indefinitely as proven by Russell Bourke's endless testing[citation needed] as it is used slowly for keeping the rings full of oil to hold and use to lubricate. Oil was shown to be used slowly by the dropfull as needed, but checking the quantity and cleanness of it was still recommended

The lubricating oil in the base is protected from combustion chamber pollution by an oil seal over the connecting rod.

The piston rings are supplied with oil from a small supply hole in the cylinder wall at bottom dead center.

Claimed and Measured Performance

Efficiency 0.25 lb/h /hp is claimed - about the same as the best diesel engine,[2] or roughly twice as efficient as the best two strokes. This is equivalent to a thermodynamic efficiency of 55.4%, which is an exceedingly high figure for a small internal combustion engine. In the test witnessed by a third party the actual fuel consumption was 1.1 hp/lb/h,[3] or 0.9 lb/h/hp, equivalent to a thermodynamic efficiency of about 12.5%, which is typical of a 1920s steam engine.[4]

Power to weight 0.9[5] to 2.5 hp/lb is claimed although no independently witnessed test to support this has been documented. The upper range of this is roughly twice as good as the best four stroke production engine shown here,[6] or 0.1 hp/lb better than a Graupner G58 two stroke.[7] The lower claim is unremarkable, easily exceeded by production four stroke engines, never mind two strokes.[8].

Emissions Achieved virtually no hydrocarbons (80 ppm) or carbon monoxide (less than 10 ppm) in published test results, however no power output was given for these results, and NOx was not measured. A diesel engine at idle may give the same results[citation needed].

Low Emissions The engine is claimed to be able to operate on hydrogen or any hydro-carbon fuel without any modifications, producing only water vapor and carbon dioxide as emissions.

Engineering Critique of the Bourke Engine

The Bourke Engine has some interesting features, but the extravagant claims[9] for its performance are unlikely to be borne out by real tests[citation needed]. Many of the claims are contradictory.[10]

1) Seal friction from the seal between the air compressor chamber and the crankcase, against the conrod, will reduce the efficiency.[11]

2) Efficiency will be reduced due to pumping losses, as the air charge is compressed and expanded twice but energy is only extracted for power in one of the expansions per piston stroke.[12][13]

3) Engine weight is likely to be as high because it will have to be very strongly built to cope with the high peak pressures seen as a result of the rapid high temperature combustion.[14]

4) Each piston pair is highly imbalanced as the two pistons move in the same direction at the same time, unlike in a boxer engine.[15]. This will limit the speed range and hence the power of the engine, and increase its weight due to the strong construction necessary to react the high forces in the components.[16]

5) High speed two-stroke engines tend to be inefficient compared with four-strokes because some of the intake charge escapes unburnt with the exhaust.[17]

6) When the charge is transferred from the compressor chamber to the combustion chamber it will cool down, reducing the efficiency[citation needed] of the engine.[18]

7) Use of excess air will reduce the torque available for a given engine size.[19]

8) Forcing the exhaust out rapidly through small ports will incur a further efficiency loss.[20]

9) Operating an internal combustion engine in detonation reduces efficiency due to heat lost from the combustion gases being scrubbed against the combustion chamber walls by the shock waves.[21]

10) Emissions - although some tests have shown low emissions in some circumstances, these were not necessarily at full power. As the scavenge ratio (ie engine torque) is increased more HC and CO will be emitted.[22]

11) Increased dwell time at TDC will allow more heat to be transferred to the cylinder walls, reducing the efficiency.[23].

12) When running in auto-ignition mode the timing of the start of the burn is controlled by the operating state of the engine, rather than directly as in a spark ignition or diesel engine. As such it may be possible to optimize it for one operating condition, but not for the wide range of torques and speeds that an engine typically sees. The result will be reduced efficiency and higher emissions.[24]

13) If the efficiency is high, then combustion temperatures must be high, as required by the Carnot cycle, and the air fuel mixture must be lean. High combustion temperatures and lean mixtures cause nitrogen dioxide to be formed.



An eye-witness account of a Bourke Engine being tested --

Bourke-Engine.Com --

Running engine and Cad modeling --

Commercial Bourke Engine development status and measurements --

Bourke engine videos. ---

Bourke Engine Project, LLC ---


Running Bourke 30 C.I engine --

Bourke home movie - 200 C.I truck and tug boat engine, disassembly of 30 CC engine, demo of scotch yoke, static and dynamic balance, first engine, aircraft engine, assembly of rod/yoke assembly --

How the Bourke Engine works ---

Built in 1954. This is Russell's first 30 cubic inch, 30+ HP production engine built for public use. The claims made, except for the unusually high rpm's or the workability of extremely high compression ratios, are true based on real world tests. The key to it's much higher efficiency is simply increased time at  Top Dead Center 'TDC'.

 Back in the 1940's Russell Bourke set out to solve various problems with the conventional engines of that era. During his career as an instructor on internal combustion engines he soon ended up discarding many pre-conceived notions, fixed ideas and incorrectly duplicated theories of how to create the same end result as a steam engine using pressure as the prime mover by converting hydrocarbon based fuels to create pressure against a piston driving it downward in a cylinder and converting it into rotary motion.

The first basic and workable theory was in order to create the needed pressure against a piston,  combustion of hydrocarbons and air in an enclosed chamber was mandated! In order to accomplish real work it was theorized that 4 separate cycles. 'INTAKE' of air and fuel, 'COMPRESSION' thereof, spark or pressure ignited expansion of those gasses ' POWER' and finally removal of the spent gasses, 'EXHAUST' was necessary.

Long ago, Dr. Otto came up with the first practical working engine based on this theory which was a 4 stroke type. It completed 4 cycles in a very literal way in that it had an INTAKE stroke, a COMPRESSION stroke, a POWER stroke and finally and EXHAUST stroke. Do you see the literal translation? The 4 Stroke Cycle was born.

The combustion chamber had to be valved in order to enable the cylinder to admit air and fuel and to emit spent gasses and it needed a crankshaft to drive things. There was quite a bit of  parasitic power robbing equipment added to accomplish the above complete cycle. Anyway, the first internal combustion piston engine was born and basically it hasn't changed one bit since!

Ever since then we have been basically stuck with the Otto cycle to drive anything that requires a 4 stroke/cycle diesel or gasoline engine. The problem isn't so much in Dr. Otto's interpretation of original theory or Dr. Diesel's decision to stick with what works.

This includes 2 stroke and turbine engines as well. They are although much simpler and able to yield more power per pound of weight, still prone to similar limitations.

Thermodynamically speaking they are flawed relative to their stoichiometric limitations and their complete inability to achieve even a hint of adiabatic efficiency.

Although they do work, none of these engine types are capable of adiabatic operation in that their efficiency is gauged based upon fuel rich stoichiometric ratios.

Regardless of an engine, be it 2 stroke, 4 stroke or turbine type, they are all inefficient stoichiometric engines in that they emit harmful waste products into the atmosphere! They needlessly pollute our world due to an incomplete combustion process with a great deal of lost heat energy that could and should otherwise be put to work!

Regardless of that and to be fair, It remains a fact that conventional engines have worked well for decades and kept the world chugging along faithfully for a long time. But at what cost?

We are all seeing the cost now as Russell Bourke predicted decades ago and tried to help prevent! I don't have to tell you what that is as you wouldn't be reading this now if you didn't know or at least suspect that something can be done about it! Yes, the effect is overall environmental degradation due to improperly and incompletely converted hydrocarbons and other toxic substances and gasses!

The work engineers and chemists have done, their innovations as well as improvements of conventional engines and hydrocarbon fuels of all types are greatly acknowledged and appreciated. From my perspective, engineers are generally extremely bright intelligent people who solve problems and create! The greater majority of them have a passion for helping their fellow inhabitants live better, take care of and preserve our natural resources.

The drive of this website is what Russell Bourke the inventor, Melvin Vaux, John Allen, Roger Richard and a host of others including myself have been talking about and trying to prove for a long time. Something CAN be done about it!

As Russell Bourke advocates in his Documentary, there is and has been a better way to squeeze power out of a pound of fuel without wasting it and harming the environment for over 60 years now. Russell Bourke is responsible for this discovery and will always be greatly appreciated and honored for his ingenious and insightful contributions!

We at Bourke Engine Com are carrying on his work in his honor and in the name of a better world where people can breath fresh air!


Per reports received from Melvin Vaux who knew and worked with Russell, the Bourke 400 was actually designed and built under contract with American Motors Corporation by Russell Bourke and Melvin Vaux. Melvin was Russell's protégé during that time.

The 400 was a heavy duty engine designed to be a standard replacement engine built for trucks and tug boats of that era. Per Melvin Vaux, after it had been test run for about 15 minutes or so as per contract, AMC took it away from Russell and never put it to use as they just couldn't get their heads wrapped around it's operation and tried to make it run like a rich 15:1 a/f stoichiometric engine when it was designed and ran fine with ultra lean air fuel ratio's. Per the Documentary the 400 cu. in. engine produced around 200 plus horse power at only 2000 RPM!

Since Russell Bourke and Mr. Vaux claimed they were the only ones who really knew how to make it run in super lean mode, AMC's engineers were lost and they gave up on it all together.

It has been rumored by Melvin Vaux that the 400 4 cylinder was born out of the 200 cubic inch 2 cylinder Bourke cycle engine that Melvin sized up from the original Bourke 30 before Russell took him on as his understudy. Evidently when Russell saw Melvin's calling card, a light went on and the 400 was born! Melvin incorporated a half shaft crankshaft using a square cupped yoke instead of the 4 piece scotch yoke connecting rod setup as in an original Bourke 30 engine. Not so much an original idea as it was novel on Melvin's part. Melvin's design did accomplish one thing and that was a true 1 piece connecting rod/scotch yoke assembly.

Trouble was that in order to keep Melvin's design from bending and breaking at the cup, he had to incorporate a slider plate as a means to keep the setup from breaking. In my opinion this arrangement offers no fundamental improvement over Russell's original design. Same movement, same stroke, same dwell time at TDC and BDC and actually there's no where to mount timing equipment or pumps etc. because there's only one half of a crankshaft sticking out the PTO end. Was Melvin's engine design any better. Evidence of his workmanship and the results thereof say absolutely NOT based on my own personal observations of Melvin's workmanship which is shoddy at best compared to Russell and his obvious jealousy of Russell based on his history working with Russell.

Even Melvin's latest creation, the DeVaux 4 cylinder boxer is no more efficient than the original Bourke design. In fact it's less efficient, less powerful and more complex than the original Bourke 30 ever was!

The 400 4 cylinder engine was only static estimated @ 200 HP and 500 Ft. Lb. torque at 2000 RPM! It never ran a real test and no one knows the actual power it made based on interviews with Melvin Vaux in 2001. But Melvin Vaux had been running his 2 cylinder 200 cubic inch Bourke twin on natural gas as an irrigation pump for a long time and up until recently in the last 10 years before he retired and turned all his engines over to another company with the hopes that they would finally get something useful done with his version of the original Bourke engines which are in fact a far cry from the original Bourke engine design.

Per Melvin Vaux, the Bourke 400 was made due to Russell's abandonment of the 30, the radial 4 cylinder engines and the H 4 cylinder, in an attempt to make enough money to support his wife Lois after he was gone.

Russell was very ill and knew he was dying. A sad and pre-mature ending for an incredibly ingenious man who cared deeply about his fellow man and the environmental damage he knew was going to result from the improper design and use of conventional engines and carbon based fuels well ahead of time. Now we see exactly what Russell was talking about all around us! Don't we. At least those who can see that is. Russell lived a very full life as you will find in the Bourke Engine Documentary. Lois was a genuine angel and backed Russell up 100%, up to and after Russell's passing.

 Russell Bourke was indeed a visionary man. There have been and are still many who carry on his dream and his work. We are part of that group. We are proud of it!

 The key thing is that the Bourke engine will still run as clean and green as Russell said they will! They do run unusually lean air fuel and high compression  ratio's. It's all in the dwell time and the simplicity of the Scotch Yoke mechanism that accomplishes a shorter  moment arm and longer torque period with less bore and stroke and moving parts than any conventional engine including Wankles. of equal power that are keys to improved efficiency in any internal combustion engine!

Russell Bourke, the inventor, made several claims about his engine in his "Bourke Engine Documentary" and other published articles. A summary of those unique claims are as follows:

Emissions:  Russell Bourke, the inventor, stated the exhaust components were carbon dioxide and water vapor.
Exhaust Temperature: Russell Bourke, the inventor, stated that matches could be held in the exhaust without igniting.
Multi-Fuel Capable: Russell Bourke, the inventor, stated the engine would run on any low grade fuel (diesel, jet fuel/kerosene, home heating oil, brown distillate, ect.).
Fuel Consumption: Russell Bourke, the inventor, claimed a brake-specific fuel consumption (BSFC) of .25 pounds of fuel per horsepower hour.
Simplicity: With only two (2) moving parts, the simplicity of this engine is self evident.
Reliability: Russell Bourke, the inventor, stated he tested the engine for 2,000 hours of marine use on an outboard motor lower unit with no detectable wear.
Power-to-Weight Ratio: Based on the testing that Russell Bourke performed on this engine, the power-to-weight ratio will be 2.5 or greater.
Operational Costs: Based on reliability, fuel consumption, and mutli-fuel tests, this engine will be very economical to operate.

Video clips:

Roger Richard can be contacted at:
[email protected]
Business Phone - Wheeler One -- 207-255-6888

Bob Zigler can be contacted at:
[email protected]
Home Phone (248) 673-3186

Business Address:
The Bourke Engine Project LLC
P.O. Box 300967
Waterford, Mi 48330-0967 USA

Bourke Engine

The Bourke engine was designed by Russell Bourke in the late 1930s, who endeavored to improve upon the Otto cycle engine. Despite finishing his redesign and building several working engines; bad luck (WWII breaking out), bad health and a know-best attitude compounded to prevent his engine from ever coming to market despite its claimed advantages. Well into the 2000's there are several small groups extolling the virtues of the design. The Bourke engine has two opposed cylinders with the pistons in a Scotch yoke mechanism. Because the motion of the pistons is a perfect sine wave with regards to time vs displacement the fuel burns in a smaller volume, and so burns hotter. The Bourke engine also has a looser coupling with the output shaft, preventing excess vibration. The intake valves are replaced by ports, saving on parts. This article or section is missing references or citation of sources. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today ( cars and trucks, generators, etc). ... German soldiers at the Battle of Stalingrad World War II was the most extensive and costly armed conflict in the history of the world, involving the great majority of the worlds nations, being fought simultaneously in several major theatres, and costing tens of millions of lives. ... The Scotch Yoke is a mechanism for converting the horizontal motion of a slider into rotational motion or vice-versa. ...

Unfortunately the design features that increase its efficiency create emission problems. The higher combustion temperatures combined with the increased cycle time around top-dead-center lead to increased nitrogen oxide emissions. This more than anything else has stopped the Bourke engine from gaining widespread acceptance today.

Scotch yoke instead of connecting rods to translate motion to rotary motion...
Fewer moving parts...
Smoother operation...
Longer percentage of cycle spent at top-dead-center and bottom-dead-center for more complete combustion and exhaust scavanging...
Two power strokes for every rotation from the opposed pistons instead of one every other rotation (4-stroke) resulting in nearly twice the power at a given engine speed...
High compression and temperatures to cause an instantaneous and adiabatic reaction as opposed to a drawn out combustion...
Lean fuel/air misture combined with the adiabatic reaction resulting in zero unburnt hydrocarbons in the exhaust...
Sealed underside of the piston to isolate the fuel/air mixture from the crankcase...
Eliminate the need to mix oil with the fuel as with standard 2-cycle engines...
Prevents the piston ring blow by from polluting the crankcase oil extending the life of the oil...

Bourke Engine Documentary by Lois Hain Bourke

Transmission for Piston and Crankshaft Assemblies
USP # 2,122,676

[ PDF ]


Internal Combustion Engine
USP # 2,122,677

[ PDF ]

Crankcase Ventilation Means
USP # 2,172,670

[ PDF ]

Scans of Articles

Unidentified Reference ---

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Bourke Engine Documentary ( Excerpt ) ---

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Hot Rod Magazine ( July 1954 )

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Sport Aviation ( March 1980 )

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Ultralight Flyer ( December 1984 )


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