M120

A 1,340 cc liquid/air-cooled flat-four with dual-channel FADEC and a 2.43:1 reduction drive. Designed for flight schools and first-time builders: mogas-compatible, field-serviceable, every part number priced in the open book.

Role
Baseline flat-four
Status
Shipping — serial 0341 and counting
Spec rev
F
Catalogue lines
37
M120 flat-four, three-quarter view: sand-cast crankcase, finned barrels, black crinkle cam covers and the offset reduction drive
Studio render
DRY MASS 62.4 KGTBO 2 000 HPOWER 120 HPFUEL MOGAS 91E10

Look closer

Captured from the same scene you can orbit above.

Close on a cylinder head: safety-wired stud nuts, the MARTLET M160T cover badge and the twin plug leads
Twin-plug heads

Twin-plug heads

Safety-wired stud nuts, cast head number, and two independent plugs per cylinder fed from separate FADEC channels.

Close on the induction plenum: machined trumpets, throttle body and hose-clamped runners into the heads
Induction

Induction

Machined trumpets in a cast plenum, one throttle body, hose-clamped runners into each head. Nothing to lean, nothing to ice.

Close on the crankcase top deck: the riveted identification plate reading M160T, serial and works
Crankcase

Crankcase

Vertically split, through-bolted, sand-cast in Bristol. The cast part number is on the sump flank where a mechanic can read it.

Specification and price

M120 type dataSPEC REV F
Configuration
Flat-four, horizontally opposed
Displacement
1,340 cc
Max power
120 hp @ 5,500 rpm
Cruise power (75%)
90 hp @ 4,900 rpm
Reduction drive
2.43 : 1 helical, torsional damper
Dry mass
62.4 kg
TBO
2,000 h
Fuel
91E10 mogas / UL91 / 100LL
Fuel burn (75%)
17.1 L/h
Cooling
Liquid-cooled heads, air-cooled barrels
Ignition & injection
Dual-channel FADEC, auto altitude compensation
Alternator
600 W integrated PM, dual regulators
Propeller flange
SAE-1 / hydraulic governor pad optional
Price, firewall-forwardEX-WORKS FILTON
$24,800

Firewall-forward, ex-works Filton

Power and torque, measured on the cellCELL DATA
035701051400501001502002,0002,5003,0003,5004,0004,5005,0005,500Crank rpmhpN·m
PowerTorque
Power

Installation

Firewall-forward, side elevation.

Installation drawingM120-FWF
612 mm overall542 mmMartlet AeroM120 FWFSide elevSheet 1 of 1Scale NTSRev E

Envelope and mount

Overall envelope 612 × 782 × 542 mm. Dynafocal mount ring, SAE-1 flange, standard cowl lines published as DXF in the installation manual. Every hose, clamp and adapter in the firewall-forward kit is a catalog line item.

Full installation drawings, mount loads and CG tables are in the Installation Manual (Rev E) — free, like all our documentation.

Get the manuals
Firewall-forward exhaust: swept primaries with weld beads, EGT bosses and the collector
Firewall kit

Parts for the M120

Full parts book
Part no.DescriptionGroupPrice
MA-000-1101Crankshaft, forged EN40B, nitridedCore$1,840
MA-000-1103Connecting rod, forged, matched pairCore$386
MA-000-1106Piston, forged 2618 alloy, with rings & pinCore$214
MA-000-1110Main bearing set, trimetal, stdCore$172
MA-000-1114Crankcase half, sand-cast A356-T6, leftCore$940
MA-000-1115Crankcase half, sand-cast A356-T6, rightCore$940
MA-000-1121Camshaft, billet, with followersCore$610
MA-000-2102Cylinder barrel, air-cooled, plateau-honedCylinder & Head$452

37 catalog lines fit the M120. All priced, all orderable.