How did it work? Mazda wanted an engine that would take the rotary well & truly into the 80's. 12 months after the introduction of the HB series, this engine turned the sedate looking Cosmo into a real "Jekyll & Hyde" car that was to be the prelude for there JC spec Cosmo of the 90's. Using an Hitachi ( HT-18 ) turbo, the analog controlled EFI computer devilered it's mix via 2 "high flow" injectors mounted in the engines centreplate. The air mix would arrive via a staged throttle body & progressive metering measured via a TPS to the ECU. Combining the relatively small turbo with it's short intake manifolding ( intercoolers wern't common in the early 80's ) endowed the 12A with instant throttle response devoid of any lag. The trade off however was to be found in the engines top end power.

Mazda never intended the 12A Turbo to be a high RPM screamer, the marketing of it within the boundries of a normal sedan proved that it's low & mid range response was were the typical driver would use it's abilities. To drive a 12A Turbo powered Cosmo & knowing your power is instantly available breeds confidence. However the real pleasure is in it's un-assuming manner. In standard form a 15 second quarter mile elapsed time is what makes this 90's car from the 80's such a great "everyday" car.

Rated at 160 hp for it's first 12 months the 12A recieved a redesigned "impact blade" turbocharger for the 84 model year & an increase of 5 hp taking it to it's better known 165 hp figure. Providing boost from as low as 1500 rpm it's rated 6 psi would keep the engine well provided to the 6500 rpm peak. After this peak it's small HT-18 turbo would simply run out of puff requiring the next gear up-change.