Asso 750
Preserved Asso 750
Type	W 18 piston engine
National origin	Italy
Manufacturer	Isotta Fraschini
First run	1934

The Isotta Fraschini Asso 750 was an Italian W 18 water-cooled aircraft engine of the 1930s. Produced by Isotta Fraschini the engine displaced just under 48 L (2,900 cu in) and produced up to 940 hp (700 kW). Together with the Asso 200 and the Asso 500 the Asso 750 was part of a family of modular engines, that used common and interchangeable components to lower production costs.

The W-18 Asso 750 had three six-cylinder in-line banks made of chrome-manganese steel, each joined by a single cast aluminum head for each bank of cylinders.

A version with an effective power of 940 hp (700 kW) was optimized for the Savoia-Marchetti S.55X used for the trans-Atlantic flight of Italo Balbo.

Asso 750

Direct-drive, unsupercharged.

Asso 750 R.

Development with modified crankcase and crankshaft, fitted with a 0.658:1 reduction gear. Maximum power output 940 hp (700 kW).

Asso 750 R.C.

Asso 750 R.C.35

The 750 R. fitted with a supercharger, rated altitude of 3,500 m (11,500 ft).

Asso 750 M

A 57.25 L (3,494 cu in) racing development with 150 mm (5.9 in) bore and 180 mm (7.1 in) stroke, for the Macchi M.67, re-designated Asso 1000 Ri.

• CANT Z.501 (early versions)
• Caproni Ca.111
• Macchi M.C.77
• Savoia-Marchetti S.55
• Savoia-Marchetti S.62
• Savoia-Marchetti S.78

At the Italian Air Force Museum two Isotta Fraschini Asso 750 are exhibited: A direct-drive Asso 750 and an Asso 750 R.C.35 with reduction gear and supercharger.

Data from Il motore Isotta Fraschini Asso 750 ^[1][2]

• Type: W-18 liquid/water-cooled
• Bore: 140 mm (5.5 in)
• Stroke: 170 mm (6.7 in)
• Displacement: 47.6 L (2,900 cu in)
• Length: 2,196 mm (86.5 in)
• Width: 1,060 mm (42 in)
• Height: 1,060 mm (42 in)
• Dry weight: 630 kg (1,390 lb)

• Valvetrain: Overhead valves 2x inlet and 2x exhaust per cylinder
• Supercharger: No supercharger fitted to this variant: supercharger available in other variants - (R.C.35 rated to 3,500 m (11,500 ft)).
• Fuel type: Gasoline 87 Octane
• Oil system: pressure
• Cooling system: Liquid/water
• Reduction gear: Not fitted to this variant: reduction geared variants available (0.658:1 R. and R.C.35).

• Power output: Normal 800 hp (600 kW) at 1700 rpm; Take-off 850 hp (630 kW) at 1750 rpm; Max 900 hp (670 kW) at 1900 rpm
• Compression ratio: 5.6:1
• Specific fuel consumption: 0.295 kg/kWh (0.485 lb/(hp⋅h))
• Oil consumption: 0.00114 kg/kWh (0.00187 lb/(hp⋅h))
• Power-to-weight ratio: Normal 0.95 kW/kg (0.58 hp/lb) max 1.129 kW/kg (0.687 hp/lb)

Related lists

• List of aircraft engines

Wikimedia Commons has media related to Isotta Fraschini Asso 750.

• Cei, Leoniero; Fiore, Amedeo (1934). Il motorista d'aviazione (in Italian). Milan: Ulrico Hoepli.
• "Jotti da Badia Polesine". Annuario dell'Aeronautica Italiana. Milan.: Libreria Aeronautica: 222. 1934.
• "Foreign Aero Engines at Olympia". Flight. XXI No. 30 (1074): 761–778. 25 July 1929. Retrieved 8 November 2018.
• Vicenzi, Ugo (October 2021). "Aces High: Isotta Franchini's "Asso" Powerplant Series". The Aviation Historian (37): 42–51. ISSN 2051-1930.