The Avia M 337 (originally designated the Walter M337) is an inverted six-cylinder air-cooled inline engine. It was developed by the Czechoslovak company as a six-cylinder derivative of the four-cylinder M 332 engine, going into production in 1960. An unsupercharged version of the M 337 is designated as the LOM M137. Production transferred to Avia in 1964, and to Letecke Opravny Malesice (LOM) in 1992.

This article includes a list of general references, but it lacks sufficient corresponding inline citations. (October 2013)

M 337
Right side view of a Walter M337; the front cylinder is hidden by the engine cowling
Type	six-cylinder inverted inline piston engine
National origin	Czechoslovakia
Manufacturer	Walter Aircraft Engines/Avia/LOM
Major applications	Let L-200 Morava Zlín Z 43

Variants

M 337A

Basic supercharged engine - not rated for aerobatics

M 337R

Modified for pusher installation

M 337AK

modified oil system for unlimited inverted flying. "Snap" aerobatics permitted.

M 337AK1

AK fitted with alternator instead of generator

M 337B

Increased max running speed (3000 rpm) - increased power - 175 kW (235 hp).

M 337BK

Aerobatic version of B.

M 337C

Increased compression ratio - 188 kW (252 hp)

M 137A

Unsupercharged version of M 337 130 kW (180 hp) take-off power. Aerobatics allowed.

M 137AZ

As M 137A, with filtered air feed

M 437

Gear ratio 0.7:1 180 kW (240 hp)

Applications

• AeroVolga LA-8C
• Falconar SAL Mustang
• Let L-200 Morava
• Zlín Z 526, Z 726
• Zlín 142
• Zlín Z 43

Specifications (M 337)

Data from Jane's All The World's Aircraft 1980-81 [1]

General characteristics

• Type: 6-cylinder inverted air-cooled supercharged inline engine
• Bore: 105 mm (4.13 in)
• Stroke: 115mm (4.53 in)
• Displacement: 5.97 L (364.3 in³)
• Length: 1,410 mm (55.51 in)
• Width: 472 mm (18.58 in)
• Height: 628 mm (24.72
• Dry weight: 148 kg (326.3 lb)

Components

• Valvetrain: OHC two camshaft operated valves per cylinder, sodium filled exhaust valve
• Supercharger: Centrifugal
• Fuel system: Low-pressure fuel injection
• Fuel type: Min 72-78 Octane
• Oil system: Dry sump pressure feed system
• Cooling system: Air-cooled

Performance

• Power output: 157 kW (210 hp) at 2,750 rpm (take-off)
• Power-to-weight ratio: 1.06 kW/kg (0.64 hp/lb)

References

Wikimedia Commons has media related to Walter M337.

• Taylor, John W R, ed. (1980). Jane's All The World's Aircraft 1980-81. London: Jane's. ISBN 0-7106-0705-9.
• http://www.walterjinonice.cz/historie-spolecnosti-walter Archived 2019-08-03 at the Wayback Machine