Is a 20B engine hard to find?

Yes, due to limited production (around 7,500 units) and JDM-only release, finding a clean 20B engine takes time and diligence. Most available today are imports sold through specialty dealers or online auctions.

How much does a 20B rotary engine cost?

Prices range from $12,000 for unverified used units to over $25,000 for fully rebuilt crate engines. Most tested, import-grade engines sell between $14,000 and $17,000.

What cars used a 20B engine?

The 20B-REW was used exclusively in the 1990–1995 Mazda Eunos Cosmo (JC series), a luxury grand tourer sold only in Japan. No other production vehicle came with this engine from the factory.

Can I install a 20B engine in an RX-7 or Miata?

Technically yes, but it requires extensive modifications: custom mounts, wiring, cooling, and tuning. Due to size, weight, and ECU complexity, it's a major undertaking best handled by experienced builders.

How do I verify a 20B engine is in good condition?

Request a recent compression test (7.0+ bar per rotor), inspect for leaks or damage, confirm completeness of parts, and verify the engine ran recently. Video evidence of startup is ideal.

Where to Buy a 20B 3 Rotor Engine and What to Watch For

If you're searching for a 20b 3 rotor engine for sale, you're likely restoring a rare Mazda Eunos Cosmo or building a high-performance rotary-powered project car. The 20B-REW is one of the most sought-after production triple-rotor engines ever made, known for its smooth power delivery and JDM heritage. However, due to limited original production and growing collector interest, finding a reliable unit at a fair price requires careful research, verification of condition, and awareness of common pitfalls in the used rotary market.

Understanding the Mazda 20B-REW 3-Rotor Engine

The Mazda 20B-REW is a twin-turbocharged, three-rotor Wankel engine produced from 1990 to 1995 exclusively for the Japanese domestic market (JDM) Mazda Eunos Cosmo. With a displacement of approximately 2.0 liters (654cc x 3), it delivers around 280–300 horsepower in factory tune, though many units produce more when tested independently 1. Its sequential twin-turbo system—where one turbo operates at low RPM and both engage at higher RPM—provides linear power without the typical lag associated with forced induction.

⚙️ Key specs:

Configuration: Triple-rotor, twin-turbo (sequential)
Displacement: 1962 cc (654cc per rotor)
Horsepower: 276 hp (JDM regulated); real-world output often exceeds 300 hp
Torque: ~300 lb-ft
Compression Ratio: 9.0:1
Fuel System: Electronic fuel injection
Engine Code: 20B-REW

This engine was never officially sold outside Japan, making every unit available internationally an import. As such, availability, documentation, and authenticity vary significantly by region and seller.

Why Is the 20B So Rare and Sought After?

🔍 The rarity of the 20B stems from several factors:

Limited Production Run: Only about 7,500 Eunos Cosmos were built during the 1990–1995 period, all equipped with the 20B-REW 2.
No Official Export: Mazda did not offer this model or engine in North America, Europe, or Australia through official channels.
High Failure Rate if Neglected: Rotary engines demand meticulous maintenance; many imported units have been poorly stored or operated incorrectly.
Cultural Icon Status: Featured in films, video games, and tuner culture, the 20B has cult status among rotary enthusiasts.

Because of these factors, even non-running cores can command premium prices, especially those with matching numbers, low mileage, or complete ancillary systems (ECU, wiring harness, turbos).

Where Can You Find a 20B 3 Rotor Engine for Sale?

🛒 Today, most buyers source a 20B engine through online marketplaces, specialty JDM importers, or rotary-focused performance shops. Below are the primary sources:

eBay – Broad Selection, Varying Quality

eBay hosts numerous listings for complete 20B-REW engines, ranging from $12,000 to $18,000 depending on condition, mileage, and completeness. Listings often include:

Complete long blocks with turbos, manifolds, and intercoolers
Original ECU and wiring harness (critical for plug-and-play swaps)
Mileage between 40,000–80,000 km (often verified via JDM odometer records)

⚠️ Caution: While eBay offers buyer protection, verifying compression test results, service history, and authenticity is essential. Some sellers provide videos of the engine running; always request this proof.

JDM Import Specialists – Higher Trust, Premium Pricing

Dealers like JDM Nagano, JDM Westcoast, and similar U.S.-based importers specialize in sourcing clean, tested 20B engines directly from Japan. These companies typically:

Provide compression test data (e.g., 7+ bar across all rotors)
Offer installation support or core exchange programs
Import legally with full documentation (title, emissions compliance where applicable)

📍 Example: A 1990–1995 JDM 20B REW from JDM Westcoast sells for around $14,999, including engine-only delivery 3. This reflects a balance between reliability and cost compared to auction-style platforms.

Performance Builders & Crate Engine Suppliers

For those seeking guaranteed reliability, companies like Pettit Racing and Billet Rotary Store offer rebuilt or fully engineered 20B crate engines. These are not stock units but upgraded builds featuring:

New apex seals, housings, bearings
Porting and balancing
Upgraded turbos or standalone management systems

🔧 Pettit Racing notes that a street-ported, blueprint-built 20B can start at $4,500 if your core components are usable—though full turnkey solutions may exceed $20,000 4. Billet Rotary Store in Australia also offers custom 20B builds as part of their 13B–39B lineup, emphasizing global shipping options.

Alibaba.com – Industrial Supplier Channel

Some industrial suppliers list remanufactured or used 20B engines on Alibaba.com, primarily targeting repair shops or bulk buyers. These listings may appear cheaper initially ($8,000–$12,000), but:

Shipping logistics and import duties are often not included
Verification of actual engine origin and testing procedures can be difficult
Communication barriers and longer lead times increase risk

🌐 Buyers should treat Alibaba leads cautiously and only proceed after securing detailed inspection reports, video evidence, and clear return policies.

What to Look for When Buying a 20B Engine

✅ Purchasing a 20B isn't just about price—it's about verifying mechanical integrity and completeness. Here’s what matters most:

1. Compression Test Results

All three rotors should show balanced readings. Healthy 20B engines typically measure 7.0–8.5 bar (100–125 psi). Anything below 6.0 bar suggests seal wear or housing damage. Always ask for a recent, documented dry/wet compression test.

2. Completeness of Ancillaries

A complete 20B swap-ready package includes:

Original ECU (essential for managing sequential turbos)
Full wiring harness (engine-side connectors intact)
Turbos, intercooler piping, throttle body
Oil and coolant lines (if possible)

Omitting any of these increases complexity and cost during installation.

3. Mileage and Service History

Low-mileage units (<60,000 km) are preferred, but consistent maintenance outweighs mileage alone. Ask for:

Service records (especially oil changes and spark plug replacements)
Storage conditions (dry vs. humid environments affect corrosion)
Last time the engine ran

4. Physical Inspection (If Possible)

Check for:

Rust on intake manifolds or exhaust ports
Cracks in the aluminum casing (especially near mounting points)
Missing sensors or broken mounts
Signs of overheating (discoloration, warped surfaces)

5. Legal and Compliance Considerations

In the U.S., engines over 25 years old qualify for import under the 25-Year Rule without needing EPA certification. However, state-level emissions rules (e.g., California CARB) may still apply upon registration. Confirm local regulations before purchase.

Seller Type	Avg. Price Range	Pros	Cons
eBay Sellers	$12,000–$18,000	Wide selection, buyer protection	Varying quality, limited verification
JDM Importers	$14,000–$17,000	Tested units, documentation, support	Premium pricing
Performance Shops	$18,000+	Rebuilt, warrantied, optimized	High cost, longer wait times
Industrial Suppliers (e.g., Alibaba)	$8,000–$12,000	Potential savings	High risk, unclear provenance

Common Misconceptions About the 20B Engine

❗ Despite its legendary status, several myths persist:

Myth 1: "All 20Bs Are High-Mileage Junk"

Reality: Many surviving engines have under 60,000 km and were well-maintained. Japanese owners often treated the Eunos Cosmo as a luxury GT, not a daily driver.

Myth 2: "You Can Swap in Any Rotary ECU"

Reality: The 20B-REW uses a unique sequential turbo strategy requiring the factory ECU or a highly tuned standalone system (e.g., Haltech, MoTeC). Generic RX-7 ECUs won’t work.

Myth 3: "It’s Just Like a 13B or 26B"

Reality: The 20B has different port timing, turbo setup, and lubrication requirements. Experience with smaller rotaries doesn’t guarantee success with a 20B.

Cost Breakdown: How Much Should You Pay?

💰 Pricing varies based on condition and source:

Used, Unverified (eBay): $12,000–$14,000
Tested, JDM-Imported: $14,000–$16,000
Rebuilt Core (Shop Labor Only): $4,500+ (parts extra)
Turnkey Crate Engine: $18,000–$25,000+

Additional costs to consider:

Shipping: $800–$1,500 (continental U.S.)
Import fees (if applicable): $300–$600
Installation labor: $1,500–$3,000
Custom fabrication (mounts, exhaust): $1,000+

Total project budget should realistically range from $17,000 to $30,000, depending on goals and existing infrastructure.

Alternatives to Consider

📌 If the 20B proves too expensive or complex, alternatives exist:

13B-REW (FD RX-7): More common, easier to source, lower cost (~$4,000–$7,000)
26B (Le Mans-spec): Extremely rare and costly, used in racing applications
Rotary Conversions with Standalone Management: Building a custom twin- or triple-rotor using 13B components with modern tuning

Each option trades rarity, power, and complexity differently. The 20B remains unique for its factory triple-rotor configuration and OEM refinement.

Final Tips Before You Buy

📋 Before committing to a purchase:

Verify compression test results with video or third-party inspection.
Confirm inclusion of ECU, harness, and critical sensors.
Ask about the engine’s last operational date and storage environment.
Review return policy and shipping insurance options.
Consult a rotary-specialist mechanic for pre-purchase assessment.

⚡ Remember: A cheap engine becomes expensive if it fails shortly after installation. Prioritize verifiable condition over upfront savings.

Frequently Asked Questions (FAQs)

Is a 20B engine hard to find?: Yes, due to limited production (around 7,500 units) and JDM-only release, finding a clean 20B engine takes time and diligence. Most available today are imports sold through specialty dealers or online auctions.
How much does a 20B rotary engine cost?: Prices range from $12,000 for unverified used units to over $25,000 for fully rebuilt crate engines. Most tested, import-grade engines sell between $14,000 and $17,000.
What cars used a 20B engine?: The 20B-REW was used exclusively in the 1990–1995 Mazda Eunos Cosmo (JC series), a luxury grand tourer sold only in Japan. No other production vehicle came with this engine from the factory.
Can I install a 20B engine in an RX-7 or Miata?: Technically yes, but it requires extensive modifications: custom mounts, wiring, cooling, and tuning. Due to size, weight, and ECU complexity, it's a major undertaking best handled by experienced builders.
How do I verify a 20B engine is in good condition?: Request a recent compression test (7.0+ bar per rotor), inspect for leaks or damage, confirm completeness of parts, and verify the engine ran recently. Video evidence of startup is ideal.