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Updating the Steam Engine: the Cyclone

An application of the Cyclone.

Cyclone Technologies LLP, developer of the Cyclone external combustion engine, received an Automotive Engineering International (SAE’s publication) Tech Award at the SAE World Congress in Detroit.

The Cyclone modifies the traditional Rankin cycle steam engine to deliver the use of super-critical pressure (3,200 psi) and super-heated steam (1,200° F)—normally found in high-efficiency electrical power plants—in an efficient, compact package suitable for a vehicle.

A sketch of the engine from the patent application.

The Cyclone. The engine, which uses water as both working fluid and lubricant,  consists primarily of a condenser, a steam generator and a main engine section having valves, cylinders, pistons, pushrods, a main bearing, cams and a camshaft.

Air pre-heated in a heat exchanger is mixed with fuel. An igniter burns the fuel charge as the flames and heat are directed in a centrifuge within the combustion chamber.

The combustion chamber heats the steam generator to produce high-pressure, super-heated steam.

A rocker and cam design which serves to open and close a needle type valve in the engine head controls the speed and torque of the engine. When the valve is opened, high-pressure, high-temperature steam is injected into the cylinder and allowed to expand as an explosion on the top of the piston.

Exhaust steam is directed through a condenser, in a centrifugal system of compressive condensation, consisting of a stacked arrangement of flat plates. Cooling air circulates through the flat plates, is heated in an exhaust heat exchanger and exits into the furnace. This reheat cycle of air greatly adds to the efficiency and compactness of the engine.

Efficiency. The efficiency of the Cyclone is based primary on three factors:

  • Heat Regeneration. Numerous design innovations significantly reduce the heat losses, cumulatively increasing the efficiency of the engine.

  • Super-Critical Liquid. Pressures in the range of 3,200 psi with temperatures of about 1,200° F cause super-critical vapor to act as a fluid. Maintaining the super-critical pressure, in the centrifuge process, eliminates the turbulence, backpressure events, and heat spikes that can occur during other less efficient types of super-critical processes. At these higher temperatures and pressures, the super-critical fluid carries more heat energy to the motor it powers. The Cyclone Engine is a piston engine with a special valve mechanism allowing it to operate at fluid pressures, thereby gaining multi-advantages: greater simplicity, reliability and enhanced power.

  • High compression. The Cyclone Engine is an external combustion/internal expansion engine, using variable timing, variable compression ratios and multiple heat exchangers to increases in engine efficiency. A reheat stage is included at lower compression ratios.

Cyclones can use almost any liquid or gaseous fuel. Power produced we be based on the energy content of the fuel in use. The design of the engine obviates the need for a separate cooling system.

The basic Cyclone engine is a compact, one-piece unit that can develop 3 hp per cubic inch of displacement, compared to a ballpark one horsepower per 1.5 cubic inches of displacement for a gasoline engine.

A Cyclone with three or more cylinders is self-starting—i.e., no flywheel needs to be turned by a starter.  Pulling the throttle lever activates flow through individual needle valves situated at each cylinder. From a dead stop, the engine attains its highest torque within less than one crankshaft revolution and transitions to engine horsepower at 5,250 rpm giving the Cyclone a remarkably robust power band.

The Cyclone Engine exhausts into the condenser, where the vapor is totally contained, not into the atmosphere. As a result, it requires no exhaust system muffler or catalytic converter.

Vibration is controlled because the crankshaft is counter weighted and the pulsations are balanced by equal offsetting pressures, thus requiring no harmonic dampener.

The Cyclone Engine is smaller than four-stroke internal combustion engines, with fewer parts. However, the materials handling the high operating temperatures and pressures are more expensive. At similar economies of scale, the two types of engines should be comparable in cost.

Applications. Harry Schoell, the inventor of the Cyclone, forsees a large range of applications for his engine, from small electrical generators in the 1 kW range up through medium-size cyclones for light-duty vehicles, large Cyclones of up to 1,000 hp for the heavy-duty diesel market and beyond to larger ships and generators.



James Grovenstein


What are some of the reasonds for adapting a steam engine such as the Cyclone to a motor vehicle? How about these below?

1.) The Cyclone engine would burn most any vaporizable fuel and use no engine lubricating oil. This would assuredly reduce dependence on imported oil. If this country could produce enough fuels such as methanol, ethanol, butanol, propane, compressed natural gas and perhaps a few fuels not even mentioned to power a large number of steam automobiles, dependence on imports could be greatly reduced. This reason alone should be enough incentive to look at developing a steam driven vehicle.

3.) This country is short of refining capacity according to experts I have heard on TV. Getting a permit to build a new refinery are almost impossible to get. Some refiners are getting around this by building extra capacity in existing refiners, but I don't know if this strategy can overcome the short fall in refining capacity.

2.) Hybrids are serving a purpose in reducing gasoline consumption, but the current cost of the hybrids compared to a regular gasoline driven car would require a number of years for the owner to pay back the difference in initial cost. I don't know what the payback time would be but I have read the the payback would require 3 to 5 years. In addition, there is the battery life issue. How long will the batteries last?

3.) As for spending money for development I have read that many millions of federal grant money are being spent for fuel cell developement. What is a few million more for steam engine development?

I am an old retired engineer but I still believe the steam engine should be given s shot.


Albion Zeglin

The extra efficency of a Hybrid IC engine vehicle is due to savings at low speed torque and idle. This would not help with that.

However a Hybrid Steam engine vehicle could get advantage during passing and short hill climbing by reducing the need for increased maximum power. This would normally be done on a steam engine using a steam accumulator (steam box?) or increased boiler reserve which would be impractical on the cyclone due to the supercritical pressures and temperatures.

This might be best with ultracapacitors rather than batteries. Has anyone done this weight/energy savings calculations?


This engine is the best thing to come along in a long time. It very elegantly solves a great number of problems in one fell swoop. It is unfortunate that so many persons posting comments here clearly fail to understand the potential. Compare the cyclone with a Diesel automotive power plant. Including all auxiliaries (including transmission) required to use the Diesel engine in an automitive application, the Diesel system weighs 2.5 times as much as a Cyclone automotive system of identical power output. The Cyclone is self-starting, can use almost any liquid or gaseous fuel with no modification to the engine at all, the starting torque of a 350 hp Cyclone is about 2500 ft lbs and the average torque is more than twice that of a Diesel, the lubrication quality is the same as modern internal combustion engines but only water is used, the water/steam system is a closed system that does not need to be replenished, the thermal efficiency of the Cyclone is the same as the Diesel but the net efficiency in the automotive application is better for the Cyclone because there are fewer losses in power transmission. The Cyclone has 1/5 the number of parts as the Diesel system. The operating temperatures are much lower.

I emphasize that there is NO need to hybridize an automotive drive train when the Cyclone is used. A steam engine sees far less changes in efficiency with speed and power changes as an internal combustion engine does. A hybrid steam car will not see appreciable gains in efficiency, if any.

The Cyclone has no catalytic converter or any other emissions controls equipment.... no computers. The cyclone is cleaner than any internal combustion operating today, and with NO emissions controls. The cylone has operated on diesel, biodiesel, gasoline, orange oil, ethanol, E-85, vegetable oil, waste crank case oil, crude oil, propane, butane, coal dust, and even wood flour (that's right, solids!). The cyclone can even be powered by concentrated sunlight (solar) in stationary applications.

The Cyclone engine in an automotive application is a hands down winner over internal combustion, electric, or hybrid. I welcome any discussions on the Cyclone. Please contact me.

Gunter Weiler

Where can I buy one please?

Jeff Baker

The cyclone engine would most likely operate on ALGAE - a slurry of unrefined 50% oil rich algae - that was fractionated with ultrasound, to burst the cell walls and expose the oils. And since algae yields are already being reported in the 100 to 200 tons per acre per year range, we have a win-win here. The cyclone engine can also be run on other forms of biomass slurries such as Dynamotive (Canada) fast pyrolysis bio-crude oil slurry, made from trees. Dongfeng Motor Corporation (China) is building cars that run on hydrous ethanol, 65% pure ethanol and 35% water. Surely the Cyclone engine could also run on that too. Also what should be experimented with is putting a pulsating charge on the water portion of the hydrous ethanol, so it turns into brown’s gas as it enters the combustion chamber. Then the cyclone engine would be running on a combination of spinning ethanol and hydrogen.



Juan Barturen

Thank you for your web site. A couple of my friends and I have been talking about the usefullness of the steam engine,and with todays technology, Wow it would revolutionize the auomotive industry.I remember seeing Jay Leno's old Stanley Steamer,and the power it produces, He has to start off slow or he spins the tires on the rims. I am afraid the oil companies wich run this world,would try to burry you. I am realy interested in your Cyclone engine technology, and if I could be of any help, or you can use one of my vehicles as a test bed.,Just let me Know..JB

Juan Barturen

Thank you for your web site. A couple of my friends and I have been talking about the usefullness of the steam engine,and with todays technology, Wow it would revolutionize the auomotive industry.I remember seeing Jay Leno's old Stanley Steamer,and the power it produces, He has to start off slow or he spins the tires on the rims. I am afraid the oil companies wich run this world,would try to burry you. I am realy interested in your Cyclone engine technology, and if I could be of any help, or you can use one of my vehicles as a test bed.,Just let me Know..JB


Two thing I can think of.

1) How is deionized water lubercate the parts?
2) How did they solve the sealing problem?

One reason steam engine never caught on is beside needing fuel, it also needs water. Sometime it uses water faster than burning fuel.

Raymond Paulson

Auto made 1/2 weight

Utilize engine 1/2 weight

This cuts fuel requirement 1/2

MPG is then doubled for all cars instantly

Alternative Fuels and Electric and Compressed Air Models


I want to use the steam production/condensation process of the cyclone engine but not the piston engine itself.


Has anyone seen this engine running?
I have been following this since June and even emailed the company asking where I could see a prototype running.
All I got back was a lot of double talk.
I smell a rat!


Im interrested to buy this generator put in an electrical battery-condensors-rectifiers-pressure hydrostatic ( hydraulic ) pump/compressor reservoir fluid hydraulic motors and brakes hybrid/trybrid medium size car of 100+ mpg.

Account Deleted

in a small boiler ,wot abt scale production leading to explotion of the boiler..

richard schumacher

The water is recirculated in a closed system, so undoubtedly it is demineralized water.

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