The powerplant is a horizontally opposed Lycoming six-cylinder design. It is a direct-drive or geared, air-cooled, and normally aspirated engine. The cylinders have steel barrels with aluminum heads, and the valves are operated by hydraulic lifters. The crankshaft is supported in an aluminum-alloy split case by four main bearings and one ball-thrust bearing, and lubricating oil is supplied from a 12 quart wet sump. The camshaft rides in journals that do not employ bearing inserts. The accessory housing supports two magnetos, a starter, a generator, and a dual tach drive. A spare mounting pad is included for a vacuum pump.[1][2][3][4]
All engines have an additional prefix preceding the 435 to indicate the specific configuration of the engine. There are also numerous engine suffixes, denoting different accessories such as different manufacturers' carburetors, or different magnetos.[1][2]
O-435 models
O-435
Baseline engine model, producing 175hp (130kW) at 2300 rpm, with a compression ratio of 6.25:1, a dry weight of 347lb (157kg) and fitted with a Marvel MA-4 carburetor. Type certified on February 11, 1942.[1]
O-435-A
Engine model with provisions for automotive type accessories, producing 190hp (142kW) at 2550 rpm, with a compression ratio of 6.5:1, a dry weight of 348lb (158kg) with a -8 magneto and 342lb (155kg) with a -20 magneto and fitted with a Marvel MA-4-5 or PS-5C carburetor. Type certified on February 11, 1942.[1]
O-435-A2
Engine model with a redesigned improved crankcase, cylinders, valves and valve seats, exhaust valve guides and rocker shaft bushing. It also has provisions for automotive-type accessories. It produced 225hp (168kW) at 3000 rpm, with a compression ratio of 7.5:1, a dry weight of 365lb (166kg) and fitted with a Marvel MA-4-5 carburetor. Type certified on October 19, 1949 and cancelled on February 25, 1944.[1]
O-435-A3
Type certified on January 5, 1951 and cancelled on February 8, 1955.[1]
O-435-B (military designation O-435-5)
Engine model with provisions for AN type accessories, producing 235hp (175kW) at 3000 rpm, with a compression ratio of 7.5:1, a dry weight of 362lb (164kg) and fitted with a Marvel MA-4-5 carburetor. Type certified on October 7, 1943 and cancelled on November 2, 1950.[1]
O-435-C (military designation O-435-1)
Engine model with provisions for AN type accessories, producing 175hp (130kW) at 2300 rpm, with a compression ratio of 6.25:1, a dry weight of 356lb (161kg) and fitted with a Marvel MA-4SPA carburetor. Type certified on January 11, 1943.[1]
O-435-C1 (military designation O-435-11)
Engine model, with revised type valves, valve guides, an accessory case with generator and starter drive, producing 175hp (130kW) at 2300 rpm, with a compression ratio of 6.25:1, a dry weight of 366lb (166kg) and fitted with a Marvel MA-4 carburetor. Type certified on January 2, 1948.[1]
O-435-C2 (military designation O-435-13)
Engine model, with provisions for O-435-C accessories carburetor, producing 175hp (130kW) at 2300 rpm, with a compression ratio of 6.25:1, a dry weight of 368lb (167kg) and fitted with a Marvel MA-4SPA carburetor. Type certified on January 2, 1948.[1]
O-435-K
Engine model that incorporates a GO-435-C2 accessory case and crankcase. It produces 240hp (179kW) at 3000 rpm, with a compression ratio of 7.3:1, a dry weight of 405lb (184kg) and fitted with a Marvel MA-4-5 carburetor. Type certified on January 24, 1951.[1]
O-435-K1 (military designation O-435-4)
Engine model with increased maximum continuous rating and the generator pad omitted, approved for helicopter installations. It produces 250hp (186kW) at 3000 rpm, with a compression ratio of 7.3:1, a dry weight of 405lb (184kg) and fitted with a Marvel MA-4-5 carburetor. Type certified on March 30, 1951.[1]
Civil modified military engine model, by the Associated Aircraft Modification Company, with Bendix PS-5C carburetor with 380123-1 setting. It produces 235hp (175kW) at 3200 rpm, with a compression ratio of 7.5:1, a dry weight of 405lb (184kg). Only military O-435-2 engines with serial numbers L00849-11 through L-1117-11 are eligible for this modification.[4]
GO-435 models
GO-435
Baseline geared engine model. It incorporates six 3rd-order crankshaft torsional vibration dampers and reduction gearing. It produced 210hp (157kW) at 3000 rpm, with a compression ratio of 6.25:1, a dry weight of 407lb (185kg) and fitted with a Marvel MA-4-5 carburetor. Type certified on August 30, 1944 and cancelled on November 2, 1950.[1]
GO-435-A2
Type certified on October 19, 1949 and cancelled on February 8, 1955.[1]
GO-435-C2 (military designation O-435-17)
Geared engine model which incorporates an improved crankcase and cylinder assembly. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 422lb (191kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on October 19, 1949.[1]
GO-435-C2A
Geared engine model, incorporates S6LN-20 or -21 magnetos, producing 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 438lb (199kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on January 2, 1951, cancelled on February 8, 1955 and reinstated July 15, 1955.[1]
GO-435-C2A2
Geared engine model, with a dry sump and without provisions for a hydraulic propeller control or governor, producing 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 432lb (196kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on October 24, 1957.[1]
GO-435-C2B
Geared engine model with provisions for a hydraulic propeller and governor. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 430lb (195kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on November 6, 1952.[1]
GO-435-C2B1
Geared engine model which incorporates a dual generator and vacuum pump drive. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 430lb (195kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on February 8, 1955.[1]
GO-435-C2B2
Geared engine model with S6LN-20, or -21 magnetos. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 430lb (195kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on February 28, 1956.[1]
GO-435-C2C
Geared engine model producing 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 422lb (191kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on November 24, 1953 and cancelled on July 5, 1956.[1]
GO-435-C2D
Geared engine model producing 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 420lb (191kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on July 20, 1954 and cancelled on July 5, 1956.[1]
GO-435-C2E
Geared engine model with S6LN-20, or -21 magnetos. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 420lb (191kg) and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on September 27, 1956.[1]
GO-435-D1
Geared engine model with a dry sump oil system and crosswise accessory drives. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1 and fitted with a Marvel MA-4-5 or PS-5BD carburetor. Type certified on September 25, 1953.[1]
VO-435 models
VO-435
Base model, vertically-mounted engine for helicopters, with a dry sump oil system and side-mounted AN type accessory drives. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 396lb (180kg) and fitted with a Marvel MA-4-5 or MA-4-5AA carburetor. Type certified on October 11, 1954. Was re-designated as VO-435-A1A.[2]
VO-435-A1A (military designation O-435-21)
Vertically-mounted engine model for helicopters, with a dry sump oil system and side-mounted AN type accessory drives. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 396lb (180kg) and fitted with a Marvel MA-4-5 or MA-4-5AA carburetor. Type certified on October 29, 1954. Re-designated from VO-435.[2]
VO-435-A1B (military designation O-435-6)
Vertically-mounted engine model for helicopters, with a dry sump oil system and a modified accessory section. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 391lb (177kg) and fitted with a Marvel MA-4-5 or MA-4-5AA carburetor. Type certified on June 10, 1955.[2]
VO-435-A1C (military designations O-435-23, O-435-23A O-435-23B and O-435-23C)
Vertically-mounted engine model for helicopters, with a dry sump oil system, which incorporates a crankcase and oil sump modification giving increased strength and an oil pump housing which is machined for a hydraulic pump drive. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 399lb (181kg) and fitted with a Marvel MA-4-5 or MA-4-5AA carburetor. Type certified on July 18, 1954.[2]
VO-435-A1D (military designation O-435-6A)
Vertically-mounted engine model for helicopters, with a dry sump oil system, with crankcase and oil sump modifications for increased strength. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 390lb (177kg) and fitted with a Marvel MA-4-5 or MA-4-5AA carburetor. Type certified on September 27, 1956.[2]
VO-435-A1E
Vertically-mounted engine model for helicopters, with a dry sump oil system and 6RN-200 or S6LN-204 magnetos. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 392lb (178kg) and fitted with a Marvel MA-4-5AA carburetor. Type certified on October 15, 1959.[2]
VO-435-A1F
Vertically-mounted engine model for helicopters, with a dry sump oil system. It has internal piston cooling oil jets and heavy duty cylinders and may be converted to a model TVO-435-A1A. It produces 260hp (194kW) at 3400 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 399lb (181kg) and fitted with a Marvel MA-4-5AA carburetor. Type certified on March 6, 1961.[2]
VO-435-B1A
Vertically-mounted engine model for helicopters, with a redesigned accessory drive section, a wet oil sump and a higher compression ratio. It produces 265hp (198kW) at 3200 rpm for takeoff, with a compression ratio of 8.7:1, a dry weight of 419lb (190kg) and fitted with a Marvel MA-4-5AA carburetor. Type certified on December 15, 1965.[2]
TVO-435-A1A
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system. It produces 260hp (194kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 468lb (212kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on May 12, 1961.[3]
TVO-435 models
TVO-435-A1A
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system. It produces 260hp (194kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 468lb (212kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on May 12, 1961.[3]
TVO-435-B1A (military designation O-435-25A)
Turbocharged, vertically-mounted engine model with internal piston cooling oil jets, for helicopters, with a dry sump oil system and cylinder assemblies machined for long-reach spark plugs. It produces 270hp (201kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 478lb (217kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on November 21, 1962.[3]
TVO-435-B1B
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system and TCM (formerly Bendix) S6RN-1208 and S6LN-1209 magnetos. It produces 270hp (201kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 479lb (217kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on June 20, 1966.[3]
TVO-435-C1A
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system and a T-1112 turbosupercharger. It produces 380hp (283kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 478lb (217kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on November 21, 1962.[3]
TVO-435-D1A
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system. It has a TK-0659 turbocharger and TCM (formerly Bendix) S6RN-1208 (retarded breaker) and S6LN-1209 magnetos. It produces 270hp (201kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 465lb (211kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on March 10, 1966.[3]
TVO-435-D1B
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system. It has TCM (formerly Bendix) S-200 series magnetos. It produces 270hp (201kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 464lb (210kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on February 23, 1967.[3]
TVO-435-E1A
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system and a Kelly Aerospace (formerly AiResearch) TK-0659 turbocharger. It produces 260hp (194kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 490lb (222kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on March 7, 1967.[3]
TVO-435-F1A
Turbocharged, vertically-mounted engine model for helicopters, with a wet sump oil system, different accessory section and a higher power rating. It produces 280hp (209kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 490lb (222kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on January 22, 1968.[3]
TVO-435-G1A
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system and a different automatic waste gate control setting for a higher power rating. It produces 280hp (209kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 465lb (211kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on January 11, 1968.[3]
TVO-435-G1B
Turbocharged, vertically-mounted engine model for helicopters, with a dry sump oil system and different magnetos. It produces 280hp (209kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 464lb (210kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on November 25, 1968.[3]
TVO-435-25
Turbocharged, vertically-mounted military engine model for helicopters, with a dry sump oil system. This military model is similar to the -A1A, except it has cylinder assemblies from the -B1A. It produces 260hp (194kW) at 3200 rpm for takeoff, with a compression ratio of 7.3:1, a dry weight of 493lb (224kg) and fitted with a Marvel-Schebler MA-6AA carburetor. Type certified on June 10, 1963.[3]
