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REGI US Completes Prototype RadMax Pump

Rad Max undergoes spin testing connected to standard Bridgeport.

REGI US, Inc. and Reg Technologies have completed a prototype, proof-of-concept pump that is suitable for customer demonstrations.

The RadMax Rad Max, based on RandCam/RadMax sliding-vane rotary engine technology (earlier post), is a 12-vane device that produces 48 pump actions every revolution. As a pump for water or fuel, the prototype 140-pound RadMax Rad Max has a theoretical displacement of more than 2,000 gpm at 3,600 rpm. The solution is scalable with minimal design changes, and many of the parts are interchangeable between different sized pumps.

/The completed pump prototype is 10-inches in diameter and weighs 140 pounds. Maximum pressure is 500 psi, and the pump will handle any oil or water.

Working with a customer's specifications, a production pump would include definition of performance goals, which translate into size, weight, materials, fluid to be pumped, etc. A production pump would require the design and development of production tooling for lower cost castings (aluminum, steel, other), or injection molded polymer devices.

The demonstration unit shows that a RadMax Rad Max is a positive displacement device, capable of processing approximately twice its internal volume every revolution.

This means that a production unit could have identical performance with half the size and weight of any competitive unit. Reduction of weight is a significant performance parameter for all equipment, directly translating into reduction of energy requirements.

REGI US owns the US rights to the Rand Cam/RadMax rotary technology. The RadMax engine has only two unique moving parts, the vanes (up to 12) and the rotor, compared to the 40 moving parts in a simple four-cylinder piston engine.   This design makes it possible to produce up to 24 continuous power impulses per one rotation that is vibration-free and extremely quiet.


The vanes, which are mounted parallel to the driveshaft, slide up and down along the outside of the rotor as they follow a track along the inside of the stator housing. Combustion chambers form between the rotor, stator walls and vanes, and their volumes change as the vanes move during rotation.

With 12 vanes and the resulting 24 combustion events, the engine generates 1 hp per 0.75 lb, as compared to a conventional internal-combustion engine's 1 hp per 6 or 7 lbs. The engine has a compression ratio of 20:1, and can burn a variety of fuels, including diesel.

The engine also generates lower vibrations because all the components are spinning in the same direction. There are no pistons or valves making thousands of abrupt changes per minute. The combustion chambers are also balanced around the rotor, plus the rotor acts as a flywheel to smooth out power imbalances and eliminate destructive harmonics.

The RadMax engine also has multi-fuel capabilities allowing it to operate on fuels including gasoline, natural gas, hydrogen, propane and diesel.  REGI US and parent company Reg Technologies Inc. are currently designing and testing prototype RadMax diesel engines, compressors and pumps intended for aviation, automotive, industrial processes and military applications.



All typical doubts about rotary concepts aside, I find the assertion, in the end of the piece, about the power to weight ratio of traditional combustion engines to be laughable. Depending on where you draw the line between the engine and the other parts of the drivetrain and car, a typical small car engine has a power to weight ratio of something like 2 lbs per horsepower. See: And that's not even a very distinguished design; more modern engines best that easily.


The F20C is supposedly ~330lbs fully dressed and makes ~240hp. I bet it would be close to 1:1 w/o the accessories.


4 pounds per HP might be accurate for small (lawn mower) sized engines...but it only took two of us to lift a 115 hp Volkswagen 4-cyl motor, so I doubt it was more than 300 pounds.

tom deplume

Is the weight of the cooling system included? What about fuel pumps, etc? the framework to hold the engine steady against its torque? I've read about the RandCam for nearly 20 years and still haven't seen one put up for sale.


They've been trying to make an engine out of this thing for years. It looks like they finally figured out that a good pump does not make a good engine. Hydraulic pumps don't require the same lubrication and heat transfer qualities that an internal combustion engine does. What most people (including REGI and their unfortunate investors)fail to appreciate about the modern recip piston, internal combustion engine is just what an engineering marvel the piston's oil control ring is.

The Rand Cam engine had serious heat transfer issues, its "sliding vanes" did not provide an effective, low friction gas seal, and the sliding surfaces did not have effective provisions for proper lubrication. Unless REGI comes up with legitimate, practical, cost effective solutions for these issues, this device will never be a practical combustion engine. As for a hydraulic pump, I can't imagine that it's any better than conventional rotary vane pump.

Just my humble opinion, of course.



You are probably right to a certain extent, the same statement were opposed for the Wankel engine, but Mazda finally solved the lubrication and sealling problems of the Wankel. Still the Wankel rotary engine failed to have a large success since it has an inherent problem of non constant surface / volume ratio that screw up its efficiency. But that's not the case of the RandCam engine.

But its true that REGI is not Mazda and I doubt that their capabilities can be compared to the 200M$ that Mazda spent in the improvment of the Wankel.

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