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, 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 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.
The following design features have been identified
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
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
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
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
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. 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 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, 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, or 0.9 lb/h/hp,
equivalent to a thermodynamic efficiency of about 12.5%, which
is typical of a 1920s steam engine.
Power to weight 0.9 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, or 0.1
hp/lb better than a Graupner G58 two stroke. The lower claim
is unremarkable, easily exceeded by production four stroke
engines, never mind two strokes..
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
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 for its performance are unlikely to be
borne out by real tests. Many of the claims are
1) Seal friction from the seal between the air compressor
chamber and the crankcase, against the conrod, will reduce the
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
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.
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.. 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
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.
6) When the charge is transferred from the compressor chamber
to the combustion chamber it will cool down, reducing the
efficiency of the engine.
7) Use of excess air will reduce the torque available for a
given engine size.
8) Forcing the exhaust out rapidly through small ports will
incur a further efficiency loss.
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
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.
11) Increased dwell time at TDC will allow more heat to be
transferred to the cylinder walls, reducing the efficiency..
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.
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 -- http://www.niquette.com/books/sophmag/bourke.htm
Bourke-Engine.Com -- http://bourke-engine.com/
Running engine and Cad modeling -- http://www.rogerrichard.com/4436.html
Commercial Bourke Engine development status and measurements --
Bourke engine videos. --- http://bourkeengine.net/videoclips.htm
Bourke Engine Project, LLC --- http://bourke-engine-project.com/14207.html
Running Bourke 30 C.I engine -- http://bourke-engine.com/vids/rlyruns.mpg
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 -- http://bourke-engine.com/vids/rlyruns.mpg
How the Bourke Engine works --- http://www.youtube.com/watch?v=4HkeA6AuEpY
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
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
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
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
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
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
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
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
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: http://www.bourkeengine.net/videoclips.htm
Roger Richard can be contacted at:
Business Phone - Wheeler One -- 207-255-6888
Bob Zigler can be contacted at:
Home Phone (248) 673-3186
The Bourke Engine Project LLC
P.O. Box 300967
Waterford, Mi 48330-0967 USA
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
Fewer moving parts...
Longer percentage of cycle spent at top-dead-center and
bottom-dead-center for more complete combustion and exhaust
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
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 ---
Bourke Engine Documentary ( Excerpt ) ---
Hot Rod Magazine ( July 1954 )
Sport Aviation ( March 1980 )
Ultralight Flyer ( December 1984 )
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