Mazda 12A Rotary Engine Specs, Problems, and Reliability. The Mazda 12A engine is a Wankel rotary engine produced from 1970 through 1985. The 12A is minimized in displacement the 10A engine (the first rotary engine in mass production). The engine had a two-rotor design also, the very same rotor radius. The depth was increased by 10 mm (0.39 in) to 70 mm (2.8 in) which allowed getting larger 573 cc chambers and overall displacement of 1146 cc (573×2).
The rotor housing was made of aluminum. The aluminum sides were covered with molten carbon steel. The Sheet-metal Insert Process (SIP) was used considering that 1974 for support of the rotor housing. The SIP is a sheet of steel with a chrome plated surface. The rotors were made of cast iron. Chrome-molybdenum steel was used for eccentric shafts. The rotors were equipped with aluminum/carbon peak seals.
The 12A engine had the 6PI system featured by variable induction ports. This engine likewise had a cast-iron thermal reactor to decrease exhaust emissions as newest 0866 variation of the 10A series. Some engines had an insert inside exhaust ports to minimize exhaust sound. The earlier 12A was a twin distributor rotary engine.
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12A Turbo Engine
The 12A turbo engine was produced given that 1982 to the 1989 year and used in Mazda Cosmo, Luce, and SA series RX-7. Of all the engine got electronically controlled fuel-injection system. It included semi-direct injection into both rotors at the same time. The engine got a passive knock sensing unit likewise as part of a knock-prevention system. It was the very first production turbocharged, and electronically fuel injected rotary engine in the history. The 12A Turbo at first was improved by a Hitachi HT18-BM turbocharger. The compression ratio reduced to 8.5:1.
The engine produced 160 hp (120 kW) at 6,500 rpm and 167 lb-ft (226 Nm) at 4,000 rpm. With those specs, Cosmo coupe was the fastest production automobile in Japan back then. The later models with a specially-designed smaller sized and lighter turbocharger called “Impact Turbocharger” (Hitachi’s HT18S-BM, with a smaller 57mm turbine and a 56mm compressor) had a bit more power – 165 hp (121 kW) at 6,000 rpm, and 170 lb-ft (231 Nm) at 4,000 rpm.
Mazda 12A Engine Problems and Reliability
Rotaries are developed to use oil, as long as you check your level consistently then you will not have a problem. Since rotary engines have an OMP (oil metering pump) installed on them, that is. The OMP straight pulls oil from your lubrication system and has little oil injectors on the top the engine that inject it to oil the apex/corner seals. The engine oil is not meant to be burned and leaves residue and soot after that. That triggers blocked ports, and fast peak seals warned out. This issue can be resolved by removing/disabling the OMP and run straight premix 2-stroke oil in the gas. A 2-stroke oil is crafted to be and oil burned inside a chamber without leaving behind residue.
The engine produces heat, so if you lose coolant and do not shut it off, you will be looking at some rebuild. The oil and coolant levels are critical for this engines and also are significant issues causers. It must be noted that the naturally aspirated 12A engines are even more trusted than turbo variations. The N/A 12A engine with appropriate maintenance doesn’t need a reconstruct prior to 150,000 miles. Be gotten ready for the reality that the engine takes in a great deal of fuel. Because of all rotary engines have a poor fuel efficiency.
Mazda 12A Rotary Engine Modifications
Mazda 12B engine – is the shortly produced engine which had actually improved reliability and brand-new ignition system. This engine was the first single supplier rotary engine. It was utilized in 1974-1978 Mazda RX-2 and RX-3 designs.
you must see more engine detail in here: Engine – US Cars News or you can see on wiki here
Mazda 12A Rotary Engine Specs
| Manufacturer | Mazda |
| Production years | 1970-1985 |
| Cylinder block material | Aluminum |
| Cylinder head material | – |
| Fuel type | Gasoline |
| Fuel system | Carburetor / Fuel injection |
| Configuration | Rotary engine |
| Number of cylinders | Two rotors |
| Valves per cylinder | – |
| Valvetrain layout | – |
| Bore, mm | – |
| Stroke, mm | – |
| Displacement, cc | 1,146 cc (69.93 cu in) |
| Type of internal combustion engine | Wankel engine, naturally aspirated and turbocharged versions |
| Compression Ratio | 9.4:1 (8.5:1 – turbo engine) |
| Power, hp | 100-130 hp (75-97kW)/7,000 |
| Torque, lb ft | 100-115 lb-ft (135-156 Nm)/3,500 |
| Engine weight | 348 lbs (157 kg) – with oil and water; 356 lbs |
| Firing order | – |
| Engine oil weight | 20W-50 |
| Engine oil capacity, liter | 4.2 (5.2 – dry with oil cooler) |
| Oil change interval, mile | 7500 miles (12,000)/7.5 months |
| Applications | Mazda R100, Mazda RX-2, Mazda RX-3 (Japan), Mazda RX-4, Mazda Luce, Mazda RX-7 |
