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REGI US and Reg Technologies Move Ahead with RadMax Rotary Engine

REGI US and Reg Technologies announced earlier in October that a preliminary series of tests have been successfully completed on the prototype 125hp RadMax rotary engine. The company also has a 42hp prototype engine.

Engineers at the company had made important modifications and tests over the last 90 days pertaining to the sealing of the RadMax engine and the shape of the cam. The new seals include an oil seal which will prevent the oil from going into the combustion chamber therefore eliminating excess hydrocarbons resulting in a cleaner burning engine, according to a company spokesperson. Details of the sealing will remain proprietary.

The main objectives of these tests were to eliminate oil leaks from entering the combustion chamber, and to reduce compression losses. The next phase of development will be implemented to complete an operating engine with a list of activities to support the required research, design, testing, and evaluation.

The company is negotiating with a major company to perform the comprehensive testing program required to produce a commercial engine for potential end users.

The Radmax rotary principle. Click to launch animation. Source: Reg Technologies

REGI US owns the US rights to the Rand Cam/RadMax rotary technology that is used in an engine with only 13 moving parts: the disk-shaped rotor and the axial vanes (up to 12) mounted perpendicular to the direction of rotation. The vanes slide back and forth against cam surfaces on each end of the rotor to alternatively expand and contract the chamber volume. (Earlier post.)

Through the process of these sliding vanes, combustion chambers form between the rotor, stator walls and vanes where the fuel/air mixture is injected, compressed, combusted and exhausted. Increasing the number of vanes increases the number of combustion events throughout a revolution. The original Rand Cam had two; the current version has 12.

The engine operates at lower speeds than a typical Wankel engine (less than 2,000 rpm) and at higher compression ratios: 15 and 20 to 1.

The design makes it possible to produce a total of 24 continuous power impulses per one rotation that is vibration-free and extremely quiet. The engine can operate using multiple fuels including gasoline, natural gas, hydrogen, propane and diesel. Reg Technologies is in the process of testing a Rand Cam/RadMax diesel engine for a generator application for hybrid electric cars and for unmanned aerial applications for the U.S. military.



It is compact, and the 15 to 20-1 compression ratio combined with the oil seal makes it intriguing. What is the net efficiency of this engine? Then there is the question of torque.


It can use multiple fuels including "gasoline, natural gas, hydrogen, propane and diesel". Can it use ethnol, in particular, E85? or any of the other combinations such as E10?? E100?? Just wondering.

Rafael Seidl

JJ -

at compression ratios of 15 to 20, the most likely fuel is diesel or perhaps, kerosene (for aviation apps). Note that Wankel designs were considered unsuitable for ratios above 10. I'm curious about the feasible engine-out emissions levels, given the unusual geometry of the combustion chamber. Another issue that puzzles me is how the moving parts are cooled.

A modified design with a lower compression ratio might be suitable for the other fuels you mention, with additional modifications.


Thank you, Rafael -- your posts are always level headed and right-on with out any bias.


"Reg Technologies is in the process of testing a Rand Cam/RadMax diesel engine for a generator application for hybrid electric cars"

I like the sound of that. Good luck sealing the engine though...Cooling shouldn't be that much of an issue if it has high thermodynamic efficiancy, characteristic of such high compression ratios.

Rafael Seidl

John -

high-compression engines need cooling, too. Affordable materials tend to become increasingly susceptible to fatigue and creep at elevated temperature. An LDV engines needs to last 200,000 miles. An HDV engine at least 600,000 miles.


I've watched the animation and it shows combustion occurring on the 'downward' slope of the cam (which of course is necessary to generate torque). But since this requires spark, does that eliminate diesel (compression) ignition? And how does 'decompression' before iginition on the power stroke affect efficiency? (Rafael . . what's up with that?)

James Prell

What I question is how well sealed are the sliding vanes along the side of the "rotor" ? The side loading on the vanes must be sizable when they are running 20 to 1 compression-ratios !

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