The 12R was developed by Renault in the 1930s, derived from the Renault Bengali, using the same construction techniques and being of essentially steel construction. It was based on the 4.46, a test engine developed by mounting two 6Q six-cylinder engines on the same crankshaft. The engine retained the bore and stroke of the smaller engine. The cylinders and pistons were made of forged steel and connected in pairs to an eight bearing crankshaft. The crankcase was made of aluminium alloy coated with magnesium. A centrifugal supercharger was mounted to the rear. The engine was produced in both right handed and left handed versions, the difference being the direction of propeller rotation.

Designed to be fitted to a range of aircraft, both civil and military, the engine was originally rated at 450 horsepower (340 kW) when first introduced in 1935. However, the majority manufactured, 290 out of a total production of 325, were the 500 hp (370 kW) 12Rc introduced in 1939. Of these, 120 powered the Caudron C.714 light fighter that served in World War II.

In addition to examples of the aircraft ordered the French Air Force, thirty-five were delivered to the Polish Air Force in France and a further six to the Finnish Air Force, although the latter were not used in combat.

The engine was rated between 450 and 500 hp (340 and 370 kW), although a high performance version built for the sole Caudron C.712 racing special produced 730 hp (540 kW). More than one third of production went to power the Caudron C.714 light fighter that fought in the early stages of World War II for the French and Polish Air Forces.

The most powerful version was the 12R Spécial of 1937 which produced 730 hp (540 kW) at 3250 rpm and powered the single C.712 racing aircraft derived from the fighter.

Variants:

Renault 12R
450 hp (340 kW)

Renault 12Rb
470–480 hp (350–360 kW)

Renault 12Rc
500 hp (370 kW)

Renault 12Rm
480 hp (360 kW)

Renault 12Ro
450 hp (340 kW)

Renault 12R-00
Type: 12-cylinder, air cooled V12 engine
LH rotation
Bore: 120 mm (4.7 in)
Stroke: 140 mm (5.5 in)
Displacement: 19 L (1,159 in3)
Length: 2,072 mm (81.6 in)
Width: 680 mm (27 in)
Height: 929 mm (36.6 in)
Dry weight: 439 kg (968 lb)
Valvetrain: 2 x overhead valves per cylinder operated by pushrods
Supercharger: Single speed centrifugal compressor
Fuel type: 87 Octane petrol
Cooling system: Air-cooled
Take-off power: 500 hp (373 kW) at 2500 rpm
Cruise power: 300 hp (224 kW) at 2500 rpm at 4,000 m (13,123 ft)
Military power: 450 hp (336 kW) at 2100 rpm at 4,000 m (13,123 ft)
Compression ratio: 6.4:1
Fuel consumption: 225 g/(hp•h) (0.50 lb/(hp•h))
Oil consumption: 10 g/(hp•h) (0.022 lb/(hp•h))

Renault 12R-01
500 hp (370 kW) RH rotation

Renault 12R-02
500 hp (370 kW)

Renault 12R-03
500 hp (370 kW)

Renault 12R-09
500 hp (370 kW)

Renault 12R Spécial
730 hp (540 kW)

6Q10 Renault engine, six-cylinder in 1936

Charles Lindbergh’s Atlantic Ocean crossing in 1927 inspired Renault to enter the light aero-engine market to diversify the range of engines they offered. The resulting Renault 4Ps, aka Renault Bengali 4, with 115 mm (4.5 in) bore and 140 mm (5.5 in) stroke, delivered 95 hp (71 kW) and proved popular, later versions powering several record-breaking light aircraft with up to 150 hp (110 kW).

Developed by Charles-Edmond Serre, by 1931 the 6.3-litre 4Pdi had evolved to give 110 hp (82 kW) to 120 hp (89 kW), with the adoption of 120 mm (4.7 in) bore steel cylinder liners, aluminium alloy cylinder heads attached by long studs to the crankcase, Duralumin connecting rods and magnesium alloy crankcase.

In 1946 production of the Renault 4P-01 resumed at the SNECMA factory at Arnage, until 1949, with at least 762 engines manufactured.

Variants:
Renault 4Ps
The initial version with 115 mm (4.5 in) bore and 140 mm (5.5 in) stroke, delivered 95 hp (71 kW)

Renault 4Pa

Renault 4Pb
95hp / 135kg – Caudron Luciole

Renault 4Pbi
Inverted development of the Pb retaining the 115 mm (4.5 in) bore

Renault 4Pc
Further development of the Ps retaining the 115 mm (4.5 in) bore

Renault 4Pci
inverted 4Pc

Renault 4Pde

Renault 4Pdi
Inverted, introduced 120 mm (4.7 in) bore steel cylinder liners, aluminium alloy cylinder heads attached by long studs to the crankcase, Duralumin connecting rods and magnesium alloy crankcase. 110 hp / 150 kg – Hanriot 16, 120 hp / 155 kg – Caudron Phalène

Renault 4Pei
Inverted, rated at 150 hp (110 kW) for take-off, the 4Pei entered production before WWII

Renault 4Pgi
Inverted lower rated version, giving 105 hp (78 kW) for take-off, using 73-octane fuel.

Renault 4Po

Renault 4Poi
140 hp (100 kW) with fuel injection.

Renault 4P-01
Postwar production version of the 4Pei, rated at 145 hp (108 kW) for take-off.

Renault 4P-03
As the 4P-01 but with an inverted flight Zenith carburettor

Renault 4P-05
As for the 4P-03 but with a modified oil system

Renault 4P-07
As for the 4P-03 but with a modified carburettor

Renault MV-4
Licence production of a 152hp Renault 4P variant.

Applications:
ANF Les Mureaux 160T
Aubert Cigale
Boisavia Mercurey
Caudron C.193
Caudron C.232
Caudron C.270 Luciole
Caudron C.280 Phalène
Caudron C.480 Frégate
Caudron C.510 Pelican
Farman F.230
Farman F.281
Farman F.350
Max Holste MH.52
Hanriot LH.16
Hanriot H.180
Morane-Saulnier MS.341
Nord Norécrin
Potez 36/19
SABCA S.40
Stampe et Vertongen SV-4B
Sud-Est SE-2100
Sud-Est SE-2300
Sud-Est SE-2310

Specifications:
Renault 4P-01
Type: 4-cylinder naturally aspirated air-cooled inverted in-line piston aircraft engine
Bore: 120 mm (4.7 in)
Stroke: 140 mm (5.5 in)
Displacement: 6.3 L (380 cu in)
Length: 1,729 mm
Width: 480 mm
Height: 708 mm
Dry weight: 147 kg
Valvetrain: Pushrod-actuated, single intake and single exhaust valve per cylinder
Fuel system: 1x Zenith 601GS down-draught carburettor
Fuel type: 80 Octane petrol
Oil system: Pressure fed, 3.0 kg/sq.cm (43 lbf/sq.in), dry sump
Cooling system: Air
Power output:
145 hp (108 kW) at 2,450 rpm @ take-off
140 hp (100 kW) at 2,400 rpm @ sea-level normal
110 hp (82 kW) at 2,200 rpm @ sea-level cruise
Specific power: 17.15 kW/L (0.38 hp/cu.in)
Compression ratio: 5.8:1
Specific fuel consumption: 0.186 kg/kW/hr
Oil consumption: 0.005 kg/kW/hr
Power-to-weight ratio: 0.74 kW/kg