Lycoming IO-720

IO-720
Type	Piston aero-engine
Manufacturer	Lycoming Engines
First run	1961
Major applications	Piper Comanche 400 Embraer EMB 202 Ipanema

The Lycoming IO-720 engine is a large displacement, horizontally opposed, eight-cylinder aircraft engine featuring four cylinders per side, manufactured by Lycoming Engines.^[1]

There is no carburetted version of the engine, which would have been designated O-720 and therefore the base model is the IO-720. The IO-720 and the Jabiru 5100 are the only flat-eight configuration aircraft engines currently in production.^[2]

Design and development

The engine has a fuel injection system which schedules fuel flow proportionally to the airflow, with fuel vaporization occurring at the intake ports. The engine has a displacement of 722 cubic inches (11.8 litres) and produces 400 hp (298 kW). The cylinders have air-cooled heads cast from aluminum alloy with a fully machined combustion chamber.^[1][3]

The first IO-720 was type certified on 25 October 1961 to the CAR 13 standard as amended to 15 June 1956 including 13-1, 13-2, 13-3, 13-4.^[2]

In 2009 a new IO-720-A1B cost US$113,621, with a rebuilt engine retailing for US$75,435 and a factory overhaul priced at US$66,289.^[4]

Variants

IO-720-A1A

Eight-cylinder, horizontally opposed, air-cooled direct drive, fuel injection, internal oil jet piston cooling, 722 cubic inches (11.8 litres), 400 hp (298 kW), certified 25 October 1961^[2]

IO-720-A1B

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -A1A except equipped with Bendix S8LN-1208 and S8LN-1209 magnetos, certified 22 February 1971^[2][5]

IO-720-A1BD

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -A1B except has a dual magneto, certified 30 December 1976^[2]

IO-720-B1A

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -A1A except for top exhaust cylinders and offset exhaust valve shroud tubes, certified 4 November 1965^[2]

IO-720-B1B

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -B1A except equipped with Bendix S8LN-1208 and S8LN-1209 magnetos and Bendix RSA-10ED1 fuel injection, certified 22 February 1971^[2][5]

IO-720-B1BD

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -B1B except has a dual magneto, certified 30 December 1976^[2][5]

IO-720-C1B

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -A1B except that it has up-exhaust cylinder heads, certified 22 December 1971^[2]

IO-720-C1BD

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -C1B except has a dual magneto, certified 28 January 1977^[2]

IO-720-D1B

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -A1B except has a rear type air inlet housing instead of a front inlet, certified 29 October 1973^[2][5]

IO-720-D1BD

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -D1B except has a dual magneto, certified 28 January 1977^[2]

IO-720-D1C

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -D1B except equipped with an angled fuel injector adapter, certified 15 April 1982^[2][5]

IO-720-D1CD

fuel-injected, 722 cubic inches (11.8 litres), 400 hp (298 kW), same as -D1C except has a dual magneto, certified 10 June 1977^[2][5]

Applications

IO-720-A1A

• Piper Comanche 400 - factory installation^[1][6]

IO-720-A1B

• Beechcraft 80 - Excalibur and Queen Air conversions^[5]
• Pacific Aerospace FU-24-954^[5]
• Piper PA-36 Pawnee Brave - Johnson Aircraft conversion^[1][5]

IO-720-B1B

• Aero Commander - MR. R.P.M. conversion^[5]

IO-720-B1BD

• Aero Commander - MR. R.P.M. conversion^[5]

IO-720-D1B

• Embraer EMB 202 Ipanema - factory installation^[1]

IO-720-D1C

• Piper PA-36 Pawnee Brave - Johnson Aircraft conversion^[1][5]

IO-720-D1CD

• Piper PA-36 Pawnee Brave - Johnson Aircraft conversion^[1][5]

Specifications (IO-720A)

Data from Lycoming Specialty Datasheet^[3] and TYPE CERTIFICATE DATA SHEET NO. 1E15, Revision 6^[2]

General characteristics

• Type: 8-cylinder fuel-injected horizontally opposed aircraft engine
• Bore: 5.125 in (130 mm)
• Stroke: 4.375 (111 mm)
• Displacement: 722 in³ (11.8 litres)
• Length: 46.41 In (117.88 cm)
• Width: 34.25 in (87.00 cm)
• Height: 22.53 in (57.23 cm)
• Dry weight: 597 lb (271 kg) dry

Components

• Fuel system: Bendix RSA-10AD1 fuel-injection
• Fuel type: 100LL avgas
• Cooling system: air-cooled

Performance

• Power output: 400 hp (297 kW) at 2650 rpm
• Specific power: 0.55 hp/in³ (25.2 kW/L)
• Compression ratio: 8.70:1
• Power-to-weight ratio: 0.67 hp/lb (1.10 kW/kg)

See also

• Jabiru 5100

References

1. ^ ^{a b c d e f g} Lycoming Engines (undated). "Lycoming IO-720". http://www.lycoming.textron.com/engines/series/720-series-engines.html. Retrieved 2008-12-19. 
2. ^ ^{a b c d e f g h i j k l m n o} Federal Aviation Administration (February 1988). "TYPE CERTIFICATE DATA SHEET NO. 1E15, Revision 6". http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/C3B4760B46E0F9A18525670E0056FDE0?OpenDocument&Highlight=io-720. Retrieved 2008-12-13. 
3. ^ ^{a b} Lycoming Engines (2004). "Specialty datasheet" (PDF). http://www.lycoming.textron.com/engines/series/pdfs/Specialty%20insert.pdf. Retrieved 2008-12-20. 
4. ^ Lycoming Engines (2009). "2009 Lycoming Service Engine Price List" (PDF). http://www.lycoming.textron.com/utility/global-resources/2009-Aftermarket-Engine-Price-List.pdf. Retrieved 2009-06-21. ^{[dead link]}
5. ^ ^{a b c d e f g h i j k l m} Lycoming Engines (undated). "Engine Finder". http://www.lycoming.textron.com/engines/engine-finder/home.do?action=search. Retrieved 2008-12-19. 
6. ^ Demand Media (2008). "The Piper PA-24 Comanche". http://www.airliners.net/aircraft-data/stats.main?id=301. Retrieved 2008-12-20.