Mazda Wankel engine – 12A – Encyclopedia II | Global Oneness

3 Nov 2014 | Author: | Comments Off on Mazda Wankel engine – 12A – Encyclopedia II | Global Oneness
Mazda Luce

Mazda Wankel engine – 12A – Encyclopedia II

The 12A was a bored-out version of the 10A – the rotor diameter was the same, but the depth was increased by 10#160;mm (0.4#160;in) to 70#160;mm (2.8#160;in). Each of its two rotors displaced 573#160;cc for a total of 1146#160;cc. The 12A series was produced for 15 years, from May 1970 through 1985.

In 1974, a 12A became the first engine built outside of western Europe or the U.S to finish the 24 hours of Le Mans.

In 1974, a new process was used to harden the rotor housing. The Sheet-metal Insert Process (SIP) used a sheet of steel much like a conventional piston engine cylinder liner with a chrome plated surface. The side housing coating was also changed to eliminate the troublesome sprayed metal.

The new REST process created such a strong housing, the old carbon seals could be abandoned in favor of conventional cast iron.

Early 12A engines also feature a thermal reactor, similar to the 0866 10A, and some use an exhaust port insert to reduce exhaust noise. A lean-burn version was introduced in 1979 (in Japan) and 1980 (in America) which substituted a more-conventional catalytic converter for this afterburner. A major modification of the 12A architecture was the 6PI which featured variable induction ports.


1970-1972 Mazda R100

1970-1974 Mazda RX-2, 130#160;hp (97#160;kW) and 115#160;ft.lbf (156#160;Nm)

1972-1974 Mazda RX-3 (Japan), 110#160;hp (82#160;kW) and 100#160;ft.lbf (135#160;Nm)

1972-1974 Mazda RX-4

1972-1980 Mazda Luce

1978-1979 Mazda RX-7, 100#160;hp (75#160;kW)


1979-1985 Mazda RX-7 (Japan)

1980-1985 Mazda RX-7 (USA)


1981-1985 Mazda Luce

Mazda Luce

1981-1985 Mazda Cosmo

Mazda Wankel engine – Turbo

The ultimate 12A engine was the turbocharged and fuel injected engine used in the Japan-spec Cosmo, Luce, and RX-7. It featured semi-direct injection into both rotors at once, a technique that was much more successful than it would appear. A passive knock sensor was used to eliminate detonation, and later models featured a specially-designed impact turbo which was tweaked for the unique exhaust signature of the Wankel engine.

Output was 165#160;hp (123#160;kW) at 6000#160;RPM and 186#160;Nm (137#160;ft.lbf) at 4000#160;RPM.


1982-1985 Mazda Cosmo

1982-1985 Mazda Luce

1984-1985 Mazda RX-7

Adapted from the Wikipedia article 12A, under the G.N U Free Docmentation License. Please also see

Mazda Luce
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