Monnett engines are converted from Volkswagen auto engines to aircraft engines by a conversion package developed and sold by Monnett Experimental Aircraft from 1971 in Elgin, Illinois and from 1981-1985 in Oshkosh, Wisconsin. The conversion package included the ignition system, intake manifold system and propeller hub. John Monnett, the founder, is a well-known VW engine converter and aircraft designer, builder, and restorer. He was elected a Member of the EAA Homebuilders Hall of Fame in 2001 (SA1/02) and received the 2005 City of Oshkosh/EAA Key to the City Award. The firm was in business from about 1971 to 1985, when it was sold (J86-87, SA5/03) to Innovative Aviation, Ltd. (INAV) of the UK. INAV also purchased the rights to the Lotus light-aircraft engines at that time, but went out of business in about a year. The AeroVee (O-135) below was improved upon by Monnett in the late 1990's and has been marketed as the AeroVee 2180 (O-135) by a new Monnett family firm, AeroConversions, since 2002. Details of the Monnett aircraft can be found in J72-73 through J85-86.
O-78 - - {3.031 / 2.717 / 78.4} / {77 / 69 / 1285}
Same stroke as O-97, O-102, O-112.
4cyl; Monnett 1300cc; 46hp@N/A rpm; 1971-1973; Wt = N/A.
Carbureted engine with single ignition.
AprgHBW71; J72-73.
Applications: (US) Monnett I.
O-97 - - {3.366 / 2.717 / 96.7} / {85.5 / 69 / 1585}
Same stroke as O-78, O-102, O-112.
4cyl; Monnett 1600cc SuperVee, E-Vee; 50hp@3400rpm, 60-65@4000 (TO); 1971-1985; Wt = 158#.
Carbureted engine with single ignition.
BGP; SA12/78, 5/03.
Applications: (US) Monnett II Sonerai (later designated Monnett Sonerai) Formula V racer.
O-102 - - {3.465 / 2.717 / 102.4} / {88 / 69 / 1679}
Same stroke as O-78, O-97, O-112.
4cyl; Monnett 1700cc SuperVee, E-Vee; 55hp@3400rpm, 60-65@4000 (TO); 1971-1985; Wt = 158#.
Carbureted engine with single ignition.
BGP; SA8/80, 9/80.
Applications: (US) Monnett Sonerai II; Volksplane VP-1.
O-112 - - {3.622 / 2.717 / 112.0} / {92 / 69 / 1835}
Same bore as O-133.
Same stroke as O-78, O-97, O-102.
4cyl; Monnett 1835cc E-Vee; N/Ahp@N/A rpm; 1978-1985; Wt = N/A.
Carbureted engine with single ignition.
SA1978 et al. (classified ads).
Applications: (US) Monnett Sonerai II.
O-122* - - {3.563 / 3.071 / 122.5} / {90.5 / 78 / 2007}
4cyl; Monnett 2007cc E-Vee; N/Ahp@N/A rpm; N/A-1985; Wt = N/A.
Carbureted engine with dual ignition.
SA4/98 (classified ad).
Applications: None found.
O-133 - - {3.622 / 3.228 / 133.1} / {92 / 82 / 2180}
Same bore as O-112.
4cyl; AeroVee; 80hp@3400rpm; 1980-1985; Wt = 158-161#.
Carbureted engine with single ignition.
BGP; SA2/02, 12/78, 5/03.
Applications: (US) Monnett Monex, Sonerai II L, II LT, II LTS.