R-670
Continental W670 on display
Type	Piston aircraft engine
Manufacturer	Continental Motors
First run	1934
Major applications	PT-17 Stearman M3 Stuart

The Continental R-670 (factory designation W670) was a seven-cylinder four-stroke radial aircraft engine produced by Continental displacing 668 cubic inches (11 litres) and a dry weight of 465 lb (211 kg). Horsepower varied from 210 to 240 at 2,200 rpm. The engine was the successor to Continental's first radial engine, the 170 hp Continental A-70. This engine was used on many aircraft in the 1930s and 1940s. The R-670 was widely used in the PT-17 Stearman primary training aircraft of the U.S. military.^[1]

In addition to being used in aircraft, the R-670 was used in a number of light armored vehicles of World War II.

Variants

Data from: Jane's All the World's Aircraft 1938^[2] Variants of the W670 included:

W670-K

carburetor, 5.4:1 compression, 65 Octane, front exhausts and 225 hp (168 kW)

W670-L

carburetor, 5.4:1 compression, 73 Octane, rear exhausts and 225 hp (168 kW)

W670-M

carburetor, 6.1:1 compression, 80 Octane, front exhausts and 240 hp (179 kW)

W670-N

carburetor, 6.1:1 compression, 80 Octane, rear exhausts and 240 hp (179 kW)

W670-K1

fuel injection, 5.4:1 compression, 73 Octane, front exhausts and 230 hp (172 kW)

W670-L1

fuel injection, 5.4:1 compression, 73 Octane, rear exhausts and 230 hp (172 kW)

W670-M1

fuel injection, 6.1:1 compression, 80 Octane, front exhausts and 250 hp (186 kW)

W670-N1

fuel injection, 6.1:1 compression, 80 Octane, rear exhausts and 250 hp (186 kW)

Applications

Aircraft

• American Airmotive NA-75
• Boeing-Stearman Model 75 (PT-17, N2S)
• CallAir Model A
• Cessna 190
• Eagle Aircraft Eagle 220
• Fairchild PT-23
• Funk F-23
• G class blimp
• Grumman G-164 Ag Cat
• Kellett K-2A, K-4
• Morane-Saulnier MS.317
• Timm N2T Tutor
• Waco 240-A
• Waco Standard Cabin series (UEC, UIC, UKC, UKC-S, UKS, VKS)
• Waco Custom Cabin series (UOC, VQC)
• Waco A series (UBA, ULA)
• Waco F series (UBF, UMF, UPF)

Armored fighting vehicles

• T2 Combat Car
• T4 Combat Car
• M1 Combat Car
• M2 Light Tank
• M3 Stuart
• Landing Vehicle Tracked (LVT-2, -4; LVT(A)-1, -2, -4, -5)

Specifications (R-670-K)

Data from Jane's 1938^[2]

General characteristics

• Type: Seven cylinder air-cooled radial
• Bore: 5+1⁄8 in (130.2 mm)
• Stroke: 4+5⁄8 in (117.5 mm)
• Displacement: 668 cu in (10.95 L)
• Length: 34+3⁄16 in (868.4 mm)
• Diameter: 42+1⁄2 in (1,079.5 mm)
• Dry weight: 450 lb (204.1 kg)

Components

• Valvetrain: 1 inlet and 1 exhaust valve per cylinder
• Fuel system: 1 Stromberg NA-R6 Carburetor
• Fuel type: 65 octane
• Oil system: Dry sump, one pressure pump, one scavenge pump, enclosed valve-train
• Cooling system: Air-cooled

Performance

• Power output: 225 hp (168 kW) at 2,175 rpm
• Specific power: 0.337 hp/in³
• Compression ratio: 5.4:1
• Fuel consumption: 13 US Gal/hr (49 L/hr) at cruising rpm
• Specific fuel consumption: 0.54 lb/hp/hr (0.328 kg/kW/hr) - at rated rpm
• Oil consumption: 0.4 US Gal/hr (1.5 L/hr) at cruising rpm
• Power-to-weight ratio: 0.49 hp/lb at cruising rpm