Upgrade Your Aviation Experience with Knisley Exhaust – Your Trusted Source for Lycoming O-320 Engine Expertise!

Flying a light aircraft can be a thrilling experience, and choosing the right engine is crucial for ensuring a safe and enjoyable flight. One popular engine used in many light aircraft is the Lycoming O-320. With its various variants and configurations, it has become a reliable choice for pilots across the world.

In this blog, we’ll take a closer look at the Lycoming O-320, including its power, displacement, and carburetor configurations. We’ll also explore the similarities and differences between this engine and other Lycoming engines to help you make an informed decision when selecting an engine for your aircraft.

Lycoming O-320 Light Aircraft Engine

The Lycoming O-320 engine, manufactured by Lycoming Engines, is a popular choice for light aircraft. This air-cooled, four-cylinder direct-drive engine is available in two versions, rated for either 150 or 160 horsepower. The engine has a horizontally opposed cylinder arrangement and a displacement of 320 cubic inches (5.24 L). It is used in various planes, including the Cessna 172 and Piper Cherokee. 

The Piper PA-18-150 Super Cub is typically fitted with a 150-horsepower (112 kW) Lycoming engine, although it is not uncommon to see them equipped with a 160-horsepower O-320-B2B engine variant.

Similarities With Other Lycoming Engines

The O-320 family of engines is externally similar to the Lycoming family of O-235 and O-290 from which they are derived.

The O-320 shares the same 3.875-inch (98mm) stroke as the smaller engines but produces more power with the bore increased to 5.125-inch (130mm). The design uses hydraulic tapes and also incorporates provisions for the installation of hydraulically controlled propellers.

Controllable pitch propeller models use a different crankshaft than those designed for fixed-pitch drives.

Inside the O-320

The O-320 engine uses a standard wet sump system for lubrication, which ensures the main bearings, connecting rods, camshaft bearings, taps, and thrust bearings are lubricated. Additionally, the piston pins, cylinder walls, and gears are spray lubricated.

The engine is equipped with an accessory-mounted oil pump to pressurize the oil system. A remote-mounted oil compressor, connected to the engine with a flexible hose, is also used.

The carbureted O-320 engines that produce 150 hp (112 kW) are approved for the use of 87 AKI automotive gasoline. However, models with a compression ratio of 9.0:1, such as the H2AD model, are not permitted. All 160 hp (119 kW) O-320 engines are allowed for use with 91 AKI. (Note that airframe approval is also required for the use of automotive gasoline on any certified aircraft.)

“O” or “IO”

All of these engines are essentially the same with one exception: the Model H. So, to begin with, the first letter, “O,” indicates a charred engine. If the letter “I” follows this first number, it indicates an injectable fuel system.

Carburetor and Injection Settings

Lycoming engines are available in 150 or 160 hp models and come in different versions like -A, -B, -C, or -D. These letters indicate various combinations of carburetor and injection settings as well as Type 1 or Type 2 Dynafocal or tapered mount configurations.

The heads of the engine are machined to produce either low compression (150 hp) or high compression (160 hp) versions. However, there are many other variables to consider. For instance, all the crankcases are cast on the same base model, but the lugs are machined differently for Type 1 or Type 2 Dynafocal devices.

Most carburetors and injectors are located at the bottom of the engine, except for the O-320-D carb designed for the Grumman American Cougar, which is mounted on top. In addition to this, injectors are mounted on top of Comanche Twin engines like IO-320-A, -B, and -C.

Crankshafts in Lycoming Engines

Lycoming engines may come in O-320-A1, O-320-B1, and O-320-C1 or O-320-A2, O-301-B2, and O-320-C2 variants.

The numbers after the first letter determine whether the crankshaft is hollow (No. 1 for constant speed drives) or solid (No. 2 for fixed-pitch drives).

The front engines that were used in the IO-320-A1, IO-320-B1, and IO-320-C1 models were designed for use with a constant speed propeller with 3/8-inch connecting bolts. However, there were some issues with these engines, and to solve the problem, the crankshaft flanges were changed to 7/16 inch. The new and improved engines were designated as IO-320-A3, IO-320-B3, and IO-320-C3, while the original ones became obsolete and are no longer used.

Finally, the letter following the center number in the engine determines the accessories installed, and the most common variable is the magnet, either Bendix or Slick. Sometimes, the letter D is added to the engine type, for example, O-320-H2AD, which represents a Bendix dual magnet in a single impeller-driven case.

An exception to this rule is the “H” series engines, which have faced many struggles. Cessna installed them on some of its Skyhawks, which turned out to be a true nightmare for the company. As a result, Cessna soon released them, and many of these engines have ended up in the amateur construction category with mixed success.

Expert Aircraft Exhaust System Maintenance and Repair Services for Lycoming O-320

If you need help with your aircraft’s engine exhaust system, a professional aviation repair and maintenance company can provide you with expert advice on the best Lycoming O-320 exhaust system for your specific aircraft. 

To schedule an appointment, feel free to call us at (800) 522-6990 or email us at sales@knisleyexhaust.com. Entrust your aircraft to the leaders in aircraft exhaust maintenance. Don’t hesitate to contact us today!