San Francisco to Pilot Wesport Next-Gen LNG for Heavy-Duty Trucks
Ford and PSA Launch New Efficient Diesel Families

Mazda to Display Hydrogen Rotary Engine-Hybrid Concept at Tokyo Show

Mazda Premacy Hydrogen RE Hybrid

Mazda will display a Premacy Hydrogen RE (rotary engine) Hybrid concept vehicle at the upcoming Tokyo Motor Show. The Premacy Hydrogen RE combines the dual-fuel, hydrogen/gasoline RENESIS rotary engine with a Mazda mild hybrid system.

Mazda started working with hydrogen-powered vehicles in 1991 and announced last year that it was planning to begin leasing hydrogen rotary engine vehicles starting with the RX-8 equipped with the hydrogen RE engine (which will also be on display at the Tokyo show). (Earlier post.)

The dual-fuel hydrogen-gasoline hybrid

The hydrogen rotary engine and the hybrid unit are transversely mounted at the front of the car, with the high-voltage battery located beneath the second row seats and the high-pressure hydrogen tank beside the third row seat.

The Premacy concept car has limited hydrogen range: some 100 km, or 62 miles.

Earlier prototypes of the Mazda mild hybrid system included stop-start, power assistance when the engine is at low rpm, and regenerative braking. An electric-motor-assist turbocharger system is used at low rpm, beginning at approximately 1000 rpm. Here, an electric motor assists the turbocharger to increase induction efficiency. At high rpm, the turbocharger is driven in a traditional fashion, by the flow of exhaust gas alone.

More details will be available at the show, which opens 19 October.

Mazda will also introduce its new Tribute hybrid, based on Ford’s Excape hybrid technology, at the show. (Earlier post.) Ford owns 33.4% of the Japanese automaker. (Both companies are working on hydrogen-fueled combustion engines as well.)

Mazda will also display its “Smart Idling Stop System” and the SENKU—a direct-injection rotary-engine hybrid based on the next-generation 13B DI direct injection gasoline rotary engine.

Rotary combustion engines are less fuel-efficient than conventional reciprocating engines, but they produce higher power output for a given displacement volume. In other words, the same size (displacement) engine produces more power but at the cost of worse fuel economy (and higher emissions). These combustion characteristics, combined with the nature of hydrogen, have also led many for some time have to consider the rotary combustion engine as a good platform for a hydrogen combustion engine (H2ICE).

Because it offers separate chambers for intake and combustion, the rotary engine is ideal for burning hydrogen without the backfiring that can occur in a traditional piston engine. The separate induction chamber also provides a safer temperature for fitting the dual hydrogen injectors with their rubber seals, which are susceptible to the high temperatures encountered in a conventional reciprocating piston engine. Furthermore, the rotary works well with a lean fuel mixture.


The RENESIS Hydrogen RE incorporates an electronically controlled hydrogen gas injector system. The system draws air from the side port during the intake cycle and uses dual hydrogen injectors in each of the engine’s twin rotor housings to directly inject hydrogen into the intake chambers. (Diagram at right, Click to enlarge.)

Also helping to maximize the benefits of the rotary engine in hydrogen combustion mode, the RENESIS Hydrogen RE features adequate space for the installation of two injectors per intake chamber. Because hydrogen has an extremely low density, a much greater injection volume is required compared with gasoline, thus demanding the use of more than one injector.

Typically, this can be difficult to achieve with a conventional reciprocating piston engine because of the structural constraints that prevent mounting injectors in the combustion chamber. However, with its twin hydrogen injectors, the RENESIS Hydrogen RE is both practical and able to deliver sufficient volume.



What a waste of time and money!

Mark A

Yes, a waste of time and money, on an engine that will leak and burn oil profusely. Better work on something else!


How can you say this is a waste of time or money?! Are you part of board of directors for BP or something?! This is an incredible opportunity for us to advance our method of fueling transportation with a limitless supply of energy! When was the last time you looked at the mileage on a daily-driven rx-7 with apex seals that have been upgraded to 2mm or better? Have you even done any research into the durability of this engine? Do you understand the power to weight ratio of the wankel rotary internal combustion engine? You (Lucas and Mark A) are the epitome of why we are paying $3.00 per gallon of a non-renewable fuel that comes primarily from companies based outside of the United States! I firmly believe in a world market, but we are being exploited on so many levels! If you knew that you were being used against your will to perpetuate your own dependence on the very entity using you, would you not break away from that vicious cycle? Forget the environment for a second. Focus on logistics. In the short term, it may cost more....even substantially more. But, the long-term benefits of this concept are more than sufficient to offset that cost. Hydrogen is the most abundant element in the UNIVERSE! The Wankel Rotary Internal Combustion Engine has the highest specific output of any internal combustion engine. Considering it's relative youth in the Internal Combustion Engine arena, it is the most efficient, most durable, and simplest example yet. This is an OUTSTANDING project that should have been in production already. Do some research and THEN cast your stone. Ignorance leads only in circles.


Only a waist of time if you live in the Middle East and like charging the US an arm and a leg for oil.


The Mazda rotary, based on the Wankle rotary is a wonderful engine. The work Mazda is doing on hydrogen fuel research is nothing but revolutionary.

Vikrant Dhoke

I have invented the Best Rotary, positive displacement engine, 40-50% more fuel efficient in principle than 4 stroke Reciprocating IC engine.

I have applied for Indian and International Patents


[email protected]


i had this same idea and i told my sisters boyfriend about it and he said that it was a stupid idea so i looked it up and it turns out that mazda did the same thing


Understanding of the topic is key, for Mark A yes rotary engines use MORE oil(key there is MORE because piston engines do eat oil as well) than piston engines. But on a reliability stand point 1/2q to 1q of oil or mineral oil(mineral oil can be used in rotary engines) is for it. For example,the rotors which revolve on an eccentric shaft (crankshaft) are of a iron alloy while the housing ( or chamber) they rotate in is of an aluminum alloy.Loss of coolant and resulting overheating resulting in the aluminum housing expanding faster than the iron rotors, this increases the clearances between moving parts (rotor) and stationary parts (the housing) which greatly reduce the potential for engine sizing due to over heating which can quickly occur with loss of coolant in reciprocating engines.( In fact, one installation of a 13B in an aircraft did lose all coolant and while the temperature red-lined, the engine continue to function until the pilot could land. A subsequent tear down and inspection of the engine revealed no damage other than a number of rubber seals were damaged due to the excess heat and required replacement.) Also what is this else they should work on? I like you to name a cheaper alternative to run and develop.


Andrew Jackson

The Wankle is great and I applaud Mazda for its work on improving and devolping it all this time. Leave it the Japanese... Toshiba got laughed at for trying to sell American companies transistors back in the 60s and look today where that led. GO MAZDA ZOOM ZOOM !!!!


Fantastic. Cant wait to own one. I had rotaries in the 70's (light yrs ahead but flawed), and others in the 80's (by then bulletproof). Have always expected to own another one day and this breakthrough might be it. Bring it on to production asap.

Peter Billingsley

Unbelievable... so much potential and they just don't get it... why not make it a Hydrogen Bomb between the 3rd row seats.. ?

c'mon guys.. dump the rotary-engine put a bio-fuel turbine engine in that baby.. Chrysler did it.. way back in 1962.. and the Government scrapped the project.. took the designs and put Turbine power into Tanks and large Military Vehicles.. Jumpin Jay Leno built one.. for crying out loud.. a Bio/diesel Turbine engined sports car.. it can be done and regardless of drawbacks.. like mileage.. which can be overcome i'm sure.. it is a multiple fueled vehicle hair tonic.. vanilla extract any flamable liquid will do... that Rotary Engine belongs in a Curtis Airplane..

Peter Billingsley

ps you'll shoot your eye out kidd




I am working on a rotary engine ICE that uses screw for compression. Do you see a possibility in my research? Do you have ideas for me on how to go about it? Please comment...
[email protected]

The comments to this entry are closed.