Mazda 12A Rotary: Everything You Need To Know

The Mazda 12A engine is a Wankel rotary engine produced from 1970 through 1985. The first ten horsepower and volume production model had two rotating blades with an increased diameter of 0.39 inches that allowed for larger 573 cc chambers and a total displacement of 1146cc.

This new design was used successfully on many different applications, including kit car builders, light aircraft, and hot rodders due to their relatively small but powerful engines. The engine has great potential and has a top-notch power to weight ratio.

Mazda placed the engine in different products along with NSU and Citroen as part of their collaborative venture between 1967 and 1977. 

What are Mazda 12A Rotary Engines? 

The 12A is a clever modification of the 10A engine. The rotor radius and depth remained largely unaltered. Rather than having just one chamber per rotation as in earlier models – like some other cars on this list; the Mazda 12A uses two rotors at different speeds combined to produce their power output (like Mazda’s MZR V6). 

Mazda increased the engine’s displacement by 573cc for each pair so that now 1/2 milliliters will provide adequate combustion with its 70mm wide bore spacing.

When it came to designing, Mazda wanted the ability for their rotors and magnets to be as thin as possible. The 12A’s rotor radius is identical at 10 inches, but there is 70 mm worth of depth this time around, which made a total displacement larger. 

The production of the Mazda 12A series continued for 15 years, from 1970 to 1985. And in 1974, the engine grabbed a milestone being the first engine built outside Europe or the United States to finish the 24 hours of Le Mans. 

Engine Specifications and Design:

  • Production Run: 1970 – 1985
  • Cylinder Head Material: N/A
  • Cylinder Block Material: Aluminum
  • Configuration: Rotary
  • Bore: N/A
  • Stroke: N/A
  • Valvetrain: N/A
  • Displacement: 1.2 L (1146 cc)
  • Compression Ratio: 9.4 and 8.5 (Turbo engine)
  • Weight: 356 lbs. 
  • Maximum HP: 130 HP at 7,000 RPM
  • Maximum Torque: 115 lb-ft at 3,500 RPM

Wanker Engines

These engines were originally designed to be more like the modern conception of an Internal Combustion Engine (ICE). It works by using rotational energy and gas-to-air mixing to make efficient use of air.

Mazda rotary engines are known for their power and fuel efficiency, but they sacrifice size.

Felix Wankel invented the first Wankel engine in the early 1950s to overcome some problems with other types of gas-based cars at that time, like noise or low performance due to large radiators required because it burned hotter than air would do naturally.


In 1974, a new process was used to harden the rotor housing. The Sheet-metal Insert Process (SIP) used an expensive and complicated metal insert that has been infused with chrome plating – it’s similar to what you might find in engine cylinder liners.

This innovation eliminated all those troublesome sprayed metal seams which plagued makers before now, but there were still some challenges ahead for this design.

With such strong steels being employed from both sides of these parts and other features like improved gas seals or higher bearings counts on key rotating assemblies, the engine should be built strongly. 

The rotor housing was made of aluminum. The sides were coated with molten carbon steel, which led to the creation of an ingenious process used since 1974 for reinforcement: SIP (Sheet-Metal Insert Process).

It’s a sheet metal insert punctured by several holes and then plated in chrome; this forms cracks between two plates where you can put iron or steel rods as needed – creating more strength than just welding them together.

The Mazda 12A engine had the 6PI system, which makes it so different from other engines. It also has a cast-iron thermal reactor to reduce exhaust emissions and an insert inside of its ports for smoother operation.

Noise reduction is enhanced than earlier models with twin distributor rotary designs like before the 0866 version came out with new features added onto them.

Applications of Mazda 12A Engine: 

  • 1970 – 1972 Mazda R100
  • 1970 – 1974 Mazda RX-2, 130 HP 
  • 1972 – 1974 Mazda RX-3, 110 HP
  • 1972 – 1974 Mazda RX-4
  • 1972 – 1980 Mazda Luce
  • 1978 – 1985 Mazda RX-7, 100 HP 
  • Aero Design DG-1
  • 1979 – 1985 Mazda RX-7
  • 1980 – 1985 Mazda RX-7 
  • 1981 – 1985 Mazda Luce
  • 1981 – 1985 Mazda Cosmo 

12A Turbo

The 12A Turbo was the first production turbocharged and electronically fuel-injected rotary engine in history. The vehicle also received a passive knock sensor as part of its anti-knock system to ensure that no power brakes are lost due to this technology not being perfected yet on car engines when the Honda corporation invented them. 

But rest assured, knowing your safety with these systems applied because there will never be any loss or drop off throughout operation even if something did go wrong inside as some other types may do.

The Japanese sports car, or “cosmo” as it’s known in Japan, is engineered with all-wheel drive and has an engine producing 160 HP at 6500 pm. It was also the fastest production model back then.

The later models had more power due to Hitachi’s Impact Turbocharger, which came out during their time, making these cars produce 165 HP.

Applications of Mazda 12A Rotary Engine: 

  • 1982 – 1989 Mazda Cosmo
  • 1982 – 1985 Mazda Luce
  • 1984 – 1985 Mazda RX-7

Problems Surrounding Mazda 12A Rotary Engine:

Engine problems are hard to evade because they do happen naturally due to some factors. They can happen due to age, mileage, and maintenance habits in the long run, but no matter how excellent your engine design is, there will still be issues that arise along with it due to different timelines.

Age, bad engine design, and mileage affect engines because they have been running for many years. Maintaining them can cause problems too, such as wear on parts, which leads to breakdowns or even worse accidents if not maintained properly.

Here are some issues that your Mazda 12A Rotary engine may encounter: 

1. Clogged Ports and Worn-out Quick Apex Seals

Rotary engines are known for their efficiency, but it is important to use oil correctly.

You can check your level by looking at this little device on top; if you see any missing, then that’s an indication there may not be enough flowing through these pipes into each part which would cause damage over time due to intensive wear-and-tear from friction against surfaces moving around in different directions with every turn.

The engine oil is not meant to be burned and leaves residue after that. This causes clogged pores; a quick apex seal warned out when using 2-stroke oil, which has been engineered with high-quality lubricants for it to burn without leaving behind any soot or other detrimental byproducts.

This problem can easily be solved by removing/disabling the OMP (Overall Motor Power) while running straight premix fuel through your car’s system; this will ensure you’re only putting pure gasoline instead of having some old battle-scarred motor part mixed up there. 

2. Engine Overheat

The naturally aspirated 12A engine is far more reliable than the turbo variety. With proper maintenance, you can get up to 150,000 miles out of your truck before having any issues with coolant or oil leaks, leading to costly repairs.

The engine generates heat, and you can’t afford to lose some coolant and don’t shut it off; you might be on the way to rebuilding. 

Also, take note that rotary engines consume more fuel than others due to their low fuel efficiency.


The Mazda 12A is a rotary engine that was the first engine installed with turbo and electronic fuel injection; the first to do so in history. This engine has been successful on many different applications and finished 24 hours of Le Mans, making it one of the most powerful engines ever made.

If you are looking for a powerful, stout, and reliable engine, the Mazda 12A engine is solid. 

However, always take note that the engine has relatively smaller fuel efficiency compared to other engines due to the nature of its built. Other than that, the Mazda 12A engine is incredible. Perfectly suited for curious and innovative enthusiasts. 

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