If you’re a fan of Honda’s engineering from the 80s and 90s, you’ve likely heard whispers about a special powerplant. The Honda B20A series engine stands as a unique and often misunderstood chapter in the company’s history. It wasn’t your average four-cylinder, and its story is one of innovation and specific application.
This article looks at what made this engine different. We’ll cover its design, where it was used, and how it performs even by today’s standards.
The Honda B20A Series Engine
Introduced in the mid-1980s, the B20A was Honda’s answer to a need for a larger, more torque-rich engine for certain markets and models. Unlike most Honda inline-fours of the era, it had a distinct character. It was designed to compete in a segment where displacement and mid-range power were key selling points.
Many enthusiasts confuse it with the more common B-series engines (B16, B18) that came later. But the B20A is largely a different family with its own architecture. Understanding this distinction is the first step to appreciating it.
Core Design and Technical Specifications
The B20A’s design is a fascinating blend of typical Honda efficiency and some unique choices for its time. Let’s break down its key technical features.
- Displacement and Configuration: It’s a 2.0-liter (1958 cc) inline-four cylinder engine. The bore and stroke are 81.0 mm x 95.0 mm, making it a classic “oversquare” design (bore larger than stroke). This hints at a potential for higher revs.
- Valvetrain: It used a SOHC (Single Overhead Camshaft) design with 16 valves. The head featured the classic Honda CVCC technology for cleaner emissions. The valvetrain was actuated by rocker arms, which is a bit different from the direct-acting valvetrain in later VTEC engines.
- Block and Internals: The block was a closed-deck design, which is inherently stronger than an open-deck block for handling increased cylinder pressure. This was a robust foundation. The crankshaft was supported by five main bearings for smooth operation.
- Compression Ratio: Depending on the specific version and market, compression ratios varied. They typically ranged from a modest 9.0:1 to a more performance-oriented 9.6:1.
- Power Output: Output figures differed significantly between versions. The most powerful factory version, found in the Japanese-market Prelude, was rated at approximately 160 horsepower. Other versions, particularly those for Europe and in the Accord, made between 130 and 145 horsepower.
Key Variations: B20A, B20A1, B20A2, B20A3
Not all B20A engines are the same. Honda created several variations to suit different cars and emissions regulations. Knowing the code on your block is crucial.
- B20A: The base engine, often found in the Japanese domestic market (JDM) Honda Accord and Prelude. This usually had the highest output.
- B20A1: Primarily used in the European-spec Honda Accord 2.0i and Prelude 2.0i. This version had different intake and exhaust manifolds, and a lower compression ratio to suit available fuel, resulting in lower power.
- B20A2: This is a rare version. It was used in the US-spec 1987-1989 Honda Accord LX-i. It was detuned for US emissions, featuring a different head, lower compression, and a PGMFI system. It’s the least powerful of the family.
- B20A3: Another European variant, similar to the B20A1 but with minor differences in tuning for specific models like the Accord Aerodeck.
What Cars Used the B20A Engine?
This engine wasn’t fitted to many vehicles, which adds to its rarity. Its primary applications were:
- Honda Prelude (2nd Generation, BA4/5 chassis) – JDM and European markets.
- Honda Accord (3rd Generation, CA chassis) – JDM, European, and US markets (B20A2 only).
- Honda Vigor (1st Generation) – JDM market.
It’s important to note the B20A was never offered in the popular Civic or Integra of that era. Honda reserved it for their more upscale, larger models at the time.
Performance Characteristics and Driving Experience
So, what’s it like to drive a car with a B20A? The experience is distinct from later Honda VTEC engines.
The engine is known for its strong low-end and mid-range torque. Thanks to the 2.0-liter displacement, it pulls confidently from low RPMs, making for relaxed highway cruising and easy around-town driving. The power delivery is smooth and linear, without the sudden “kick” of a VTEC engagement.
While it can rev, it doesn’t have the frenetic, high-RPM personality of a B16A. The powerband tends to peak earlier and taper off as you approach the redline, which is typically around 6800-7000 RPM. The exhaust note is deeper and more subdued compared to the rasp of a smaller Honda engine.
In period reviews, cars with the B20A were praised for their refined and effortless power. They felt quick and modern compared to rivals with more agricultural engines.
Strengths and Common Weakpoints
Like any engine, the B20A has its high points and its areas that need attention, especially as these engines age.
Strengths:
- Robust Block: The closed-deck block is very strong and can handle significant power increases with proper internal upgrades.
- Torque: Excellent low-end grunt for its era, making it feel very driveable.
- Smoothness: The five-main-bearing crank and overall design make it a smooth operator.
Weakpoints and Things to Watch For:
- Rocker Arm Wear: The SOHC rocker arm assembly can be a point of failure. The adjuster nuts can seize, and the rockers themselves can wear out, leading to noisy valve lash.
- Distributor Issues: The internal ignition coil in the distributor is a common failure point. Symptoms include misfires, stuttering, and a no-start condition.
- Oil Leaks: Valve cover gasket and distributor o-ring leaks are frequent. The rear main seal can also seep oil over time.
- Parts Availability: This is the biggest challenge today. Many engine-specific parts (like a performance head gasket or a brand-new distributor) are discontinued and very hard to find. You often rely on used parts or custom solutions.
Modification Potential and Tuning
Can you tune a B20A? Yes, but the path is more challenging than with a mainstream B-series or K-series engine. The aftermarket support is very limited.
- Basic Bolt-Ons: Intake and exhaust modifications will yield some gains, as with any engine. Finding a header specifically for a B20A is difficult; many custom-fabricate one.
- Internal Work: The strong block is a great starting point. Forced induction (turbo or supercharger) is a popular route for big power. You will need forged pistons and rods, and a solution for fuel management. The cylinder head, however, is a bottleneck for high horsepower as it doesn’t flow as well as a DOHC VTEC head.
- The “Hybrid” Route: A common and effective swap is to use the durable B20A/B20A1 block and pair it with a cylinder head from a more modern engine, like a B16A or B18C. This requires custom fabrication for mounts and manifolds, but it combines B20 torque with VTEC top-end power. This is a complex but rewarding project for a skilled builder.
Overall, modifying a B20A is a project for a dedicated enthusiast who enjoys problem-solving, not someone looking for easy, off-the-shelf power gains.
Legacy and Place in Honda History
The B20A series engine occupies a special niche. It was Honda’s premier 2.0-liter offering for a brief period before the advent of the legendary F-series and H-series engines. It demostrated the company’s commitment to refined performance and technical innovation, even in a SOHC design.
While it was eventually superseded by more advanced and tuner-friendly engines, the B20A retains a cult following. Its rarity, unique character, and robust bottom end ensure it’s remembered fondly by those who have owned one. It represents a specific moment in time when Honda was expanding its reach into new market segments.
FAQ Section
Is the B20A a VTEC engine?
No, the B20A series engine is a non-VTEC, SOHC design. Honda introduced VTEC technology later, in the early 1990s.
What is the difference between a B20A and a B20B/B20Z?
They are completely different engines. The B20A is an older, SOHC design from the 80s. The B20B/Z are later, simpler SOHC engines found in the CR-V and some older SUVs. They share almost no parts.
Can I swap a B20A into my Civic?
Technically possible, but it’s one of the most difficult Honda swaps due to its unique mounting points, wiring, and lack of aftermarket swap kits. It is not a recommended or common swap.
How much horsepower can a stock B20A handle?
The bottom end is quite strong. With good tuning, a stock B20A block can reliably handle around 250-300 horsepower with forced induction. The cylinder head and fuel system become the limiting factors well before the block.
Why are parts so hard to find for the B20A?
Because it was produced in relatively low numbers for a short time, and only for specific models in certain markets. Aftermarket companies never developed extensive support for it, and Honda has discontinued most OEM parts.
In conclusion, the Honda B20A series engine is a fascinating piece of engineering history. It offers a driving experience different from the high-revving Honda’s that came after it. For the right person, owning and maintaining one is a rewarding, if sometimes frustrating, labor of love. Its unique design and place in the Honda lineup ensure it will continue to be discussed and appreciated by enthusiasts for years to come.