Mazda 13B vs 20B: Rotary Engine Showdown

Mazda’s rotary engines, particularly the Mazda 13B vs 20B, have captivated enthusiasts with their unique Wankel design. The Mazda 13B features a two-rotor configuration, while the 20B takes it further with three rotors, delivering higher power and torque. For example, the 20B-REW produces 280 PS (206 kW) and 407 N⋅m (300 lbf⋅ft) of torque, making it a favorite for high-performance builds. The 13B, found in iconic models like the Mazda RX-7, offers a simpler design with exceptional tuning potential. Whether you’re considering an engine swap or preserving a JDM classic, understanding the differences between the Mazda 13B vs 20B is crucial for making the right choice.

Key Takeaways

• The Mazda 13B has two rotors. It is simple and great for tuning. This makes it perfect for people wanting an easy engine swap.

• The Mazda 20B has three rotors. It gives more power and torque. This makes it great for racing and high-performance cars.

• Think about your budget and goals when picking between them. The 13B costs less and is easier to fix. The 20B is stronger but costs more.

• Both engines need regular care, especially for the apex seals. Taking care of them helps the engine last longer.

• Mazda’s rotary engines are famous in racing and regular cars. The 13B is loved for old car projects. The 20B is best for racing.

Engine Design and Configuration

Mazda 13B: Two-Rotor Design

The Mazda 13B engine, a hallmark of Mazda’s engineering, features a two-rotor configuration. This design prioritizes simplicity and compactness, making it a favorite among enthusiasts for engine swaps and tuning projects. The 13B’s two-rotor layout allows for a balanced power-to-weight ratio, which is ideal for lightweight sports cars like the Mazda RX-7. Over the years, Mazda refined the 13B with various iterations, such as the 13B-RESI, 13B-DEI, and the turbocharged 13B-REW. For instance, the 13B-REW, with twin sequential turbos, delivers up to 280 horsepower, showcasing its potential for high-performance applications. Its straightforward design also makes it easier to maintain and modify, appealing to those who value accessibility and affordability.

Mazda 20B: Three-Rotor Design

The Mazda 20B takes rotary engine innovation to the next level with its three-rotor configuration. This 3-rotor engine, particularly the 20B-REW, is renowned for its exceptional power and torque output. Producing 280 PS and 407 N⋅m of torque, the 20B-REW offers a significant performance boost over the 13B. The additional rotor increases displacement, enabling smoother power delivery and greater responsiveness. This engine is a staple in high-performance builds and racing applications, where its robust design and superior output shine. However, the complexity of the three-rotor design requires more meticulous maintenance and higher costs, which may deter casual enthusiasts. Despite this, the 20B remains a symbol of Mazda’s commitment to pushing the boundaries of rotary engine technology.

Key Design Differences in Mazda Wankel Engines

The primary distinction between the Mazda 13B and 20B lies in their rotor count. The two-rotor engine of the 13B offers simplicity and ease of use, while the three-rotor engine of the 20B provides enhanced performance and smoother operation. Mazda’s engineering advancements, such as lightweight materials and improved cooling systems, further differentiate these engines. For example, the side housing material transitioned from cast iron to aluminum, reducing weight and improving thermal efficiency. Additionally, the 20B’s configuration technology addresses cooling loss issues, ensuring reliability under high-performance conditions. These innovations highlight Mazda’s dedication to refining the Wankel rotary engine for diverse applications, from street cars to track-focused builds.

The Mazda 13B vs 20B debate ultimately boils down to your priorities. If you seek a simpler, more accessible option, the 13B is an excellent choice. For those chasing peak performance and exclusivity, the 20B delivers unmatched power and prestige.

Performance Comparison

Power Output and Torque in Mazda 13B vs 20B

When comparing the Mazda 13B and Mazda 20B engines, the difference in power output and torque is significant. The 13B, with its two-rotor design, is known for its balance between performance and simplicity. While specific power figures for the 13B vary depending on the model and tuning, the turbocharged 13B-REW can produce up to 280 horsepower. On the other hand, the Mazda 20B, with its three-rotor configuration, delivers a remarkable 450 PS at 8,500 RPM and 40 kgm of torque at 8,000 RPM. This makes the 20B a powerhouse for high-performance applications.

The additional rotor in the 20B not only increases displacement but also enhances torque delivery, making it ideal for enthusiasts seeking maximum performance.

RPM Range and Responsiveness

Both engines excel in their ability to operate across a wide RPM range, a hallmark of the Wankel design. The Mazda Wankel engine performs effectively at various RPM levels, from as low as 4,000 RPM to an impressive 13,000 RPM. This flexibility allows you to experience smooth power delivery and quick throttle response, whether you’re cruising on the highway or pushing the limits on a racetrack. The 20B’s three-rotor design provides even greater responsiveness, making it a favorite for track builds and high-performance setups. However, the 13B’s simpler design ensures a more predictable and manageable driving experience, especially for those new to rotary engines.

• The Wankel engine operates effectively at:

  • 4,000 RPM for smooth cruising.

  • 13,000 RPM for high-performance scenarios.

Fuel Efficiency and Emissions

Fuel efficiency and emissions are areas where rotary engines, including the Mazda 13B and 20B, face challenges. The 13B, being smaller and simpler, tends to consume less fuel compared to the 20B. However, both engines are notorious for their relatively poor fuel economy due to the inherent design of the Wankel engine, which struggles with thermal efficiency. Emissions are another concern, as rotary engines often produce higher levels of unburned hydrocarbons. Mazda has made strides in improving these aspects, incorporating advanced cooling systems and lightweight materials to enhance efficiency. Despite these efforts, you should consider these factors if fuel economy and environmental impact are priorities.

Practical Considerations

Reliability and Maintenance of Mazda Rotary Engines

Mazda rotary engines, including the 13B and 20B, are renowned for their innovative design but require meticulous maintenance to ensure reliability. The apex seals, a critical component of the Wankel engine, demand regular inspection and replacement due to wear. Mazda has improved these seals over time, enhancing durability and reducing maintenance frequency. However, you should still expect higher upkeep compared to traditional piston engines.

The table below highlights key insights into the reliability and maintenance of Mazda rotary engines:

If you plan to use a 13B or 20B for engine swaps or tuning, understanding these maintenance requirements is essential. Regular oil changes, proper cooling system care, and timely seal replacements will help you maximize the lifespan of your rotary engine.

Cost of Ownership and Parts Availability

Owning a Mazda rotary engine involves unique costs. Maintenance and repair were initially designed to be handled at the dealer level, with scheduled intervals for replacing wear parts like gaskets. Mazda even introduced an engine exchange program, allowing dealers to rebuild and recycle engines efficiently. This program reduced downtime for customers and ensured parts availability.

Today, sourcing parts for the 13B is relatively straightforward due to its widespread use in models like the Mazda RX-7. Aftermarket support is robust, offering upgrades and performance parts for tuning enthusiasts. In contrast, the 20B racing engine is rarer, making parts more expensive and harder to find. If you’re considering a 20B for a high-performance build, be prepared for higher costs and longer wait times for components.

Applications in Mazda Vehicles and Racing

Mazda rotary engines have left a lasting legacy in both consumer vehicles and motorsports. The 13B powered iconic models like the Mazda RX-7, celebrated for its lightweight design and tuning potential. This engine remains a popular choice for swaps, offering a balance of performance and accessibility.

The 20B, on the other hand, shines in racing applications. For example, the 1987 Mazda 757 featured a modified triple-rotor Wankel engine producing 444 horsepower, competing in the Le Mans Group C class. Mazda’s rotary innovation culminated in the 1991 Mazda 787B, which delivered 681 horsepower and secured a historic victory at Le Mans. These achievements underscore the 20B’s capabilities as a racing engine.

Whether you’re restoring a classic Mazda RX-7 or building a track-focused machine, the 13B and 20B offer distinct advantages. The 13B excels in affordability and versatility, while the 20B delivers unparalleled performance for enthusiasts seeking exclusivity.

Pros and Cons

Advantages of the Mazda 13B Engine

The Mazda 13B engine stands out for its simplicity and versatility. Its two-rotor design makes it compact and lightweight, which is ideal for engine swaps and tuning projects. You’ll find it easier to maintain compared to more complex rotary engines, as parts are widely available and aftermarket support is robust. This engine’s adaptability has made it a favorite among enthusiasts restoring the Mazda RX-7 or building custom vehicles.

Key advantages include:

• Compact design: The 13B’s small size allows for better weight distribution in lightweight sports cars.

• Tuning potential: With proper modifications, the 13B can produce impressive power while maintaining reliability.

• Affordability: Parts for the 13B are more accessible and cost-effective than those for the 20B.

However, the 13B’s fuel efficiency and emissions remain challenges. For example, the 2011 Mazda RX-8, powered by a 1.3-liter rotary engine, achieved only 16/23 mpg city/highway, which is below average for its class.

Advantages of the Mazda 20B Engine

The Mazda 20B engine offers unmatched performance and exclusivity. Its three-rotor configuration delivers smoother power delivery and higher torque, making it a powerhouse for high-performance builds. This engine excels in racing applications, where its durability and output shine. For instance, a naturally aspirated 20B has been dyno-tested at 300 horsepower at the wheels, rivaling turbocharged setups.

Key advantages include:

• Superior performance: The 20B produces up to 450 PS at 8,500 RPM, making it ideal for track-focused builds.

• Durability: The 20B’s robust design ensures reliability under extreme conditions.

• Prestige: As a rarer engine, the 20B adds exclusivity to any project.

Despite its strengths, the 20B’s complexity and cost may deter casual enthusiasts. Parts are harder to source, and maintenance requires specialized knowledge.

Choosing Between the Mazda 13B and 20B

Your choice between the Mazda 13B and 20B depends on your priorities. If you value simplicity, affordability, and accessibility, the 13B is the better option. It’s perfect for restoring a Mazda RX-7 or experimenting with engine swaps. On the other hand, if you’re chasing peak performance and exclusivity, the 20B is worth the investment. Its three-rotor design offers unparalleled power and smoothness, making it a top choice for racing or high-end builds.

Consider your goals, budget, and technical expertise. Both engines represent Mazda’s innovation in Wankel rotary technology, but they cater to different needs. Whether you’re preserving a JDM classic or building a track monster, the Mazda 13B vs 20B debate ultimately comes down to your vision.

The Mazda 13B and 20B rotary engines each offer distinct advantages, catering to different needs and preferences. The 13B stands out for its accessibility, affordability, and versatility, making it an excellent choice for engine swaps or restoring iconic models like the RX-7. In contrast, the 20B delivers superior performance with its three-rotor design, ideal for track builds or high-performance enthusiasts seeking exclusivity.

When deciding between these engines, consider your goals, budget, and technical expertise. Whether you aim to preserve a JDM classic or create a track-focused machine, both engines showcase Mazda’s innovation and commitment to rotary technology. Their legacy continues to inspire enthusiasts worldwide.