Mazda · Mazda Rotary
Mazda 20B-REW
Mazda's rare production three-rotor twin-turbo engine, built for the Eunos Cosmo.
119.7
Cubic inches
The 20B-REW remains one of the only mass-production three-rotor road-car engines ever built and represented the peak of Mazda's luxury/performance rotary ambitions.
Displacement
119.7 ci
Bore
—
Stroke
—
Years
1990–1995
Key Takeaway
The 20B-REW added a third rotor to Mazda’s production rotary formula and paired it with sequential twin turbocharging. The result delivered much stronger torque and exceptional smoothness while retaining the compact length and low height that make rotary engines unique.
Technical Specifications
- Horsepower
- 280 PS in Japanese-market production specification
- Torque
- 41.0 kg-m in Eunos Cosmo production specification
- Architecture
- Three-rotor Wankel rotary
- Block
- Aluminum rotor housings with iron/steel wear surfaces
- Cylinder heads
- Not applicable — rotary architecture
- Valvetrain
- Not applicable
- Aspiration
- Sequential twin turbocharged and intercooled
- Fuel delivery
- Electronic fuel injection
The 20B-REW added a third rotor to Mazda’s production rotary formula and paired it with sequential twin turbocharging. The result delivered much stronger torque and exceptional smoothness while retaining the compact length and low height that make rotary engines unique.
Internal Specifications
Variant-specific values are labeled. Engine families that span multiple years or RPOs can have different heads, cams, induction and rotating parts, so the exact code/year always takes priority.
Notable Applications
Strengths
- Exceptional smoothness
- Strong torque for a rotary
- Huge tuning potential
Weaknesses / Watch-outs
- Rare and extremely expensive
- Complex sequential turbo system
- Specialist rebuild parts and knowledge required
Common Upgrades
- Single-turbo conversion
- Standalone ECU
- Cooling and fuel-system upgrades
Racing History & Legacy
The 20B-REW remains one of the only mass-produced three-rotor road-car engines ever sold and the peak of Mazda’s production rotary luxury/performance era.
References & Image Credit
Engine image: Taisyo · CC BY-SA 2.1 JP · source
Engineering Notes Worth Knowing
Three-rotor Wankel rotary with 1.962 L nominal displacement.
Sequential twin turbocharged and intercooled.
Electronic fuel injection.
Factory Eunos Cosmo specification: 280 PS and 41.0 kg-m of torque.
History · context · related reading
The Story Behind Mazda 20B-REW
The 20B-REW was Mazda’s most ambitious production road rotary. Built for the Eunos Cosmo, it combined three rotors, twin turbos, and luxury-car refinement in a package unlike anything else in regular production.
TorqueList Garage Reference Series
See this engine inside the full Mazda reference catalog.
The same Engine Library data now powers a more detailed mobile-friendly catalog with technical specs, variants, engineering notes, history and related stories.