Lycoming IO-540 vs Continental IO-520: An Engine Comparison

When it comes to six-cylinder piston aircraft engines, two names keep showing up in every hangar conversation: the Lycoming IO-540 and the Continental IO-520. These two powerplants have shaped general aviation for decades. They power some of the most beloved airplanes ever built — from the Piper Saratoga to the Beechcraft Bonanza — and pilots have been debating which one is better ever since.

Both engines are air-cooled, horizontally opposed, fuel-injected six-cylinders that live in the same general power class. They look similar on the outside. They even perform similarly in cruise flight. But dig a little deeper, and you start to find some real differences — in design philosophy, starting behavior, overhaul costs, maintenance habits, and how each engine responds to how you fly it.

If you're shopping for an airplane powered by one of these engines, or you're trying to understand what makes each one tick, this guide breaks it all down. By the end, you'll have a clear picture of what sets the Lycoming IO-540 vs Continental IO-520 apart — and which one might be the better fit for your mission.

Key Takeaways

The Lycoming IO-540 and Continental IO-520 are both capable, proven six-cylinder aircraft engines, but they have meaningful differences worth knowing before you buy. The IO-540 has slightly more displacement (541.5 cu in vs 520 cu in), typically produces 260–300 hp depending on the variant, and is generally considered more forgiving to operate. The IO-520 produces 285–310 hp across its variants, is known for smooth operation, and is famously installed in the Beechcraft Bonanza and Baron. The IO-540 tends to have a longer published TBO on many variants, while the IO-520's lighter weight and fuel efficiency edge can matter in some airframes.

If you're evaluating aircraft powered by either of these engines, Flying411 is a trusted resource for buyers and owners who want straightforward aviation insight without the fluff.

A Quick Background on Both Engines

Before diving into the numbers, it helps to know where these two engines come from.

The Lycoming IO-540 has been around since the late 1950s. It's a direct evolution of the four-cylinder IO-360, scaled up to six cylinders with a displacement of 541.5 cubic inches. The "I" in IO-540 stands for fuel-injected, and the "O" means horizontally opposed. Over the decades, Lycoming built dozens of variants — from carbureted O-540s to turbocharged TIO-540s to the aerobatic AEIO-540 used in competition airplanes like the Zivko Edge 540.

The Continental IO-520 was introduced in 1963 as a development of the earlier IO-346. It's also a six-cylinder, horizontally opposed, fuel-injected engine, but it displaces 520 cubic inches — slightly smaller than the Lycoming. Continental built the IO-520 in a wide range of variants: the standard IO-520, the turbocharged TSIO-520, and the geared GTSIO-520. The IO-520 laid the foundation for the later IO-550 series, which extended the stroke to push displacement to 550+ cubic inches.

Fun Fact: The Lycoming O-540 and the Continental IO-520 both power aircraft that have won competitions, set records, and logged millions of hours across commercial operations and personal flying. They are considered two of the most successful piston engine families in light aviation history.

How the Engine Designs Differ

These aren't simply two engines with slightly different numbers on a spec sheet. They reflect two distinct engineering philosophies.

The Camshaft Location Debate

One of the most talked-about differences between Lycoming and Continental engines is where the camshaft sits.

In a Lycoming IO-540, the cam lives above the crankshaft. In a Continental IO-520, it sits below. This sounds like a small detail, but it has real-world implications. With the camshaft on top in the Lycoming, the lower portion of the crankcase tends to stay better lubricated during normal operation. The Continental's bottom-mounted cam, however, can be more vulnerable to corrosion if the engine sits for long periods — a common concern for aircraft that don't fly regularly.

Heads Up: If you own or are buying a Continental IO-520-powered aircraft and it doesn't fly often, cam and lifter corrosion is a known maintenance concern. Regular oil changes and flying the airplane frequently are your best defenses.

Crankcase and Structural Design

Lycoming's crankcase is often praised for its crack-free reputation in service. Continental's 520 crankcase, while capable, has historically been considered more sensitive to thermal stress. Shock cooling — rapid temperature drops during descent — can be more of a concern with the heavily finned Continental cylinder design than with Lycoming's.

That said, both engines are products of careful engineering, and either will hold together just fine when operated correctly.

The Fuel Injection Systems

Both engines use fuel injection, but they do it differently.

The Lycoming IO-540 uses Bendix RSA-style fuel injection. It's a reliable system, but it has a reputation for being trickier to master on hot starts. If the engine is heat-soaked and you don't know the technique, you can flood it or waste time cranking. Once you learn the "knack," it's not bad — but there's definitely a learning curve.

The Continental IO-520 uses TCM's continuous-flow fuel injection system. Many pilots find it more user-friendly, especially on hot restarts. You can use the boost pump with the mixture at idle cut-off to purge vapor from the lines — a technique that makes hot starts considerably more predictable.

Pro Tip: If you're transitioning from a carbureted airplane to a fuel-injected Continental IO-520, ask an experienced pilot or your CFI to walk you through the hot-start procedure specific to your aircraft. The technique varies slightly between models.

Power Output: How Much Horsepower Are We Talking?

Both engines compete in a similar power band, but the details matter.

The Lycoming IO-540 produces roughly 235 to 310 hp depending on the variant. The IO-540-C and -D series with parallel valve heads typically make around 260 hp. The IO-540-K series with angle-valve heads can reach 300 hp. There are over 90 distinct IO-540 variants, so the horsepower output really depends on which specific engine you're looking at.

The Continental IO-520 produces 285 to 310 hp across its standard (non-turbocharged) variants. The IO-520-BB found in the Beechcraft Bonanza is a well-regarded example — it features an upgraded main crankshaft, a relocated alternator up front, and a straightforward fuel injection setup.

Good to Know: Power ratings on both of these engines can vary quite a bit depending on the specific model suffix. When shopping for an airplane, always look up the exact engine variant — not just the family name — to understand what you're actually getting.

TBO: Time Between Overhaul

TBO (time between overhaul) is one of the most important numbers in piston engine ownership. It tells you roughly how many hours the manufacturer expects the engine to run before a major overhaul.

For the Lycoming IO-540, TBO ranges from about 1,800 to 2,000 hours depending on the variant. Many of the popular IO-540 variants clock in at 2,000 hours — a strong number for this class of engine.

For the Continental IO-520, TBO ranges from approximately 1,700 to 1,900 hours on most commonly used variants, with some models listed higher depending on operating conditions. Continental's official documentation shows a wide range (1,400 to 2,200 hours across the entire 520 family) so again, the specific variant matters.

Why It Matters: TBO directly affects the long-term cost of aircraft ownership. An engine with a 2,000-hour TBO spread over a typical flying schedule of 150 hours per year means roughly 13 years between overhauls. At 100 hours per year, that stretches to 20 years — so higher TBO is especially valuable for lower-utilization owners.

Keep in mind that TBO is a manufacturer recommendation, not an FAA mandate for non-commercial aircraft. Many owners fly past TBO without issue by tracking engine health with compression checks and oil analysis. That said, most lenders, insurers, and resale buyers factor TBO closely into value assessments.

Aircraft That Use These Engines

Understanding which airframes use each engine helps you put the comparison in context.

Aircraft Powered by the Lycoming IO-540

• Piper PA-32 Cherokee Six / Saratoga — One of the most common IO-540 applications
• Cessna 206 Stationair — Utility workhorse favored by skydiving operations
• Piper Navajo — Twin-engine platform using high-output IO-540 variants
• Maule — Various bush plane configurations
• Pitts Special — Aerobatic variants use the AEIO-540

Aircraft Powered by the Continental IO-520

• Beechcraft Bonanza (V35, A36) — The IO-520-BB is a long-running pairing
• Beechcraft Baron 55/58 — Twin-engine with IO-520 variants
• Cessna 210 Centurion — Retractable single powered by the IO-520
• Cessna 185, 206 — Some models used Continental before switching to Lycoming
• Bellanca Viking 300 / Super Viking — A popular pairing
• Cessna 310 — Light twin using IO-520 variants

The Cessna 182 (Skylane) is worth noting specifically. Earlier production models used the Continental O-470, then switched to the Lycoming O-540 when Cessna restarted production in the late 1990s — partly to avoid carburetor ice issues by going fuel-injected.

Fun Fact: Cessna's switch back to the Lycoming O-540 for the restarted 182 production line is said to have been partly motivated by wanting to move away from the carbureted O-470's susceptibility to carb ice — a real-world safety factor that shaped a major airframe decision.

Lycoming IO-540 vs Continental IO-520: 9 Key Differences to Know

This is the core of the comparison. Here are the most important factors to weigh when looking at these two engines side by side.

1. Displacement and Architecture

The IO-540 has 541.5 cubic inches of displacement vs the IO-520's 520 cubic inches. Both are six-cylinder, horizontally opposed, air-cooled engines. The extra displacement in the Lycoming gives it slightly more room to breathe at lower power settings, which some pilots associate with relaxed operation and long engine life.

2. Horsepower and Performance Feel

Pilots who have flown both often describe the IO-540 as feeling "more powerful," while the IO-520 feels "smoother." Both perceptions have some basis in reality. The IO-540's larger displacement gives it a bit more torque at lower RPM, contributing to that strong feel. The IO-520's finer balancing and Continental's continuous-flow injection contribute to its smoother impression.

3. Hot Start Behavior

The Continental IO-520's fuel injection system is generally more forgiving on hot starts. The Lycoming IO-540's Bendix RSA system requires a practiced technique — flood it or rush it, and you're in for a cranking session. Once mastered, neither system is particularly troublesome, but the learning curve is steeper for the Lycoming.

4. Camshaft Design and Corrosion Risk

As mentioned earlier, the cam lives above the crank in Lycomings and below in Continentals. The bottom-mounted cam in the IO-520 can be more susceptible to corrosion during extended storage. This is a known issue with Continental camshaft designs, and it's something any pre-buy inspection should look at carefully.

5. Crankcase Durability

Lycoming's crankcase design has a long reputation for being crack-resistant in service. Continental's 520 crankcase, especially in high-horsepower turbocharged variants, has been more prone to cracking under certain stress conditions. For the standard IO-520, this is less of a concern — but it's worth noting.

6. Fuel Burn and Efficiency

Both engines consume avgas in quantities that would make a smaller four-cylinder engine jealous. At 75% power, a typical IO-540 might burn in the range of 14–16 gallons per hour, while an IO-520 is in a similar ballpark. The IO-520, being slightly smaller in displacement, may edge slightly lower on fuel burn in some installations, but the difference is generally modest. Proper leaning technique affects your actual fuel burn far more than which engine you're flying.

Quick Tip: Running lean of peak (LOP) is one of the best things you can do to reduce fuel burn and extend engine life on either engine. A GAMI injector set can help you get even mixture distribution across all six cylinders, which makes LOP operation smoother and more effective.

7. Overhaul Cost

Overhaul costs for both engines are broadly similar — typically running tens of thousands of dollars depending on what's found inside and who does the work. RAM Aircraft is well known for offering high-quality Continental IO-520 overhauls, and several shops specialize in Lycoming 540 work. The specific variant, the condition of the core, and whether you're going field overhaul vs factory rebuilt all affect the final number significantly.

8. Parts Availability and Support

Both Lycoming and Continental have solid parts ecosystems. Lycoming's network of distributors and independent shops is extensive, and the IO-540's long production run means parts are generally easy to source. Continental's support has also been strong, and many shops that work on Bonanzas and Cessna 210s have deep IO-520 experience.

For a broader look at how these manufacturers compare across their full engine lineups, the Lycoming vs Continental vs Rotax engine comparison at Flying411 covers the big picture nicely.

9. Resale Value and Aircraft Marketability

When it comes to resale, the engine you have matters — but mostly in the context of hours remaining to TBO and overall condition. A low-time IO-520 in a clean Bonanza is a strong seller. So is a freshly overhauled IO-540 in a well-maintained Saratoga. Neither engine family carries a significant market premium over the other in most cases. What matters more is where the engine is in its life cycle and what the maintenance logs show.

At Flying411, you'll find practical aircraft buying and ownership resources designed to help you make smarter decisions — without the pressure of a sales pitch.

Turbo Variants: TIO-540 vs TSIO-520

Both engine families have turbocharged versions worth knowing about.

The TIO-540 (turbocharged Lycoming) powers aircraft like the Piper Malibu Mirage in some configurations and offers strong high-altitude performance. Some variants push up to 350 hp.

The TSIO-520 (turbocharged Continental) is found in aircraft like the Cessna T210, Beech B55 Baron, and various Cessna 400-series twins. The TSIO-520 is smooth and powerful, but its reputation for requiring careful handling — especially avoiding overboosting on the first flight of the day — means the pilot's technique matters a lot.

Keep in Mind: Turbocharged variants of both engines add significant complexity and cost to ownership. Turbo systems require their own maintenance schedule, and overboost events can cause serious internal damage. Always brief turbo operations in a new-to-you aircraft before the first flight.

For a deeper dive on the Continental turbo side, the Continental IO-550 vs TSIO-550 comparison is worth reading if you're looking at higher-performance options.

What About Compared to Four-Cylinder Engines?

If you're coming from a smaller airplane and wondering how these engines fit into the broader landscape, both the IO-540 and IO-520 are six-cylinder engines in a completely different performance and cost tier compared to the IO-360 or O-320.

The step up from a four-cylinder airplane to a six-cylinder one isn't just about horsepower — it's about payload, useful load, and the kind of missions you can fly. A Piper Cherokee 235 with an O-540 hauls a lot more than a 172 with an O-320.

For pilots exploring the smaller Lycoming families, the Lycoming O-360 vs IO-360 comparison and the Lycoming O-235 vs O-320 overview are useful starting points. And for those looking at mid-range options, the Lycoming O-320 vs O-360 breakdown helps put the step-up in perspective.

How to Choose Between the Two

There's no universal answer to which engine is "better." The right choice depends on the airplane you want to own and how you plan to fly it.

Choose the Lycoming IO-540 if:

• You want a larger displacement engine known for forgiving operation
• You're buying a Piper Cherokee Six, Saratoga, or Cessna 206
• You prefer the Bendix fuel injection system once you've learned its technique
• You value a strong TBO and established overhaul network
• You fly aerobatics (AEIO-540 variant)

Choose the Continental IO-520 if:

• You're buying a Beechcraft Bonanza, Baron, or Cessna 210
• You want smooth, predictable performance and a user-friendly fuel injection system
• The specific airframe you want happens to be certificated with the IO-520
• You value the Continental's hot-start ease and smooth cruise operation

In most cases, the engine follows the airframe. You don't pick the engine and then find a plane — you find the plane you want and get familiar with its engine.

Good to Know: If you're looking at airplanes powered by Continental engines in the same performance class but with even more displacement, the Lycoming IO-540 vs Continental IO-550 comparison covers how the next-generation Continental stacks up.

Conclusion

The Lycoming IO-540 and Continental IO-520 are both time-tested workhorses of general aviation. Neither engine is dramatically superior to the other across the board. The IO-540 wins points for displacement, TBO on many variants, and forgiving operation under hard use. The IO-520 earns its reputation for smooth running, user-friendly hot starts, and powering some of the most refined aircraft in the GA fleet.

The real winner in the Lycoming IO-540 vs Continental IO-520 debate is the pilot who takes the time to learn their specific engine — its quirks, its maintenance needs, and how it responds to good habits in the cockpit.

Ready to find an aircraft with either of these powerplants? Flying411 has the resources to help you make a confident, well-informed decision.

Frequently Asked Questions

Is the Lycoming IO-540 more reliable than the Continental IO-520?

Both engines have strong reliability records when properly maintained and operated. The Lycoming IO-540 is generally considered more tolerant of less-than-perfect technique, while the Continental IO-520 rewards careful operation with smooth, efficient performance.

What aircraft use the Continental IO-520?

The Continental IO-520 is famously installed in the Beechcraft Bonanza and Baron, as well as various Cessna models including the 185, 206, 210, and 310. It's also found in the Bellanca Super Viking and several other general aviation aircraft.

How does the Continental IO-520 compare to the IO-550?

The IO-550 is a later development of the IO-520, with a longer piston stroke that increases displacement to around 550 cubic inches and boosts sustainable power output. The IO-550 generally delivers 300 hp continuously, while the IO-520 typically achieves 285–300 hp with some variants having short-duration power limits.

What is the main difference between the Lycoming O-540 and IO-540?

The "O" stands for carbureted (using a carburetor) and the "IO" stands for fuel-injected. The IO-540 uses Bendix RSA fuel injection, which eliminates carburetor ice risk and generally improves fuel distribution across all six cylinders compared to the carbureted O-540.

Does engine type affect the resale value of an aircraft?

Engine type itself matters less than the engine's time remaining to TBO, overall condition, and maintenance history. Both the IO-540 and IO-520 are well-regarded engines, and aircraft powered by either can hold strong resale value when properly maintained and documented.