AlfaRomeo 158

Technical details 158-47

Chief designer Gioachino Colombo
Technical director Orazio Satta
Numbers of frames built -
Chassis tubolar oval girders with welded crosspieces
Wheel base 2.50m
Track width front and rear 1.25m
Weight 700kg
Measures length 4190mm, width 850mm, height 1000mm, Ground clearance 150mm
Steering central, endless screw type
Wheelsaluminium alloy-spline drive wheels
TyresPirelli, front 17x550, rear 18x700
Brakeshydraulic drums al round, mechanical hand brake operating on the rear axle
Fuel tankone rear tank + one tank on the right side for a total capacity of 185lt
Oil tankin the cockpit's left side, 18lt of capacity
Coolingwatercooled, total capacity of the circuit 11 lt
Front suspensionIndependent longitudinal parallelograms, transverse semi elliptic leaf
Rear suspensionindependent, transverse semi elliptic leaf
Shock absorbers idraulic and friction shock absorbers all round
Engine Alfa Romeo 158
Type straight 8, two alloy blocks, screwed iron cylinders
Bore and stroke 58*70mm
Engine capacity 1479cc
Power 275 HP (1947-48) - 350 HP (1950)
Rev 7500 rpm (1947-48) - 8500 rpm (1950)
Compression ratio 6,5:1
Average pistons speed 17.5m/sec (1947-48) - 19.85m/sec (1950)
Effective average pressure 22.35kg/cmq (1947-48) - 25kg/cmq (1950)
Cylinder head mated with the engine's blocks, emispheric head design
Valvetrain 2 overhead valves for each cylinder, 100° angle
Valves clearance 30mm inlet and exhaust
Crankcase Elektron cast, mated with chassis trough six bearings
Crankshaft cemented steel, counterbalanced
Crankshaft bearings9 bronze bearings with antifriction metal
Connecting rod bearings-
Camshaftsdouble overhead camshafts operating on five bearings
Valve control-
Distribution control with gears operating on rollers, front position
Fuel feed under pressure with volumetric compressor, one inverted triple choke carburettor
Compressor Alfa Romeo type - engine rev * 1.32 pressure 2.5Kg/cmq
Ignition t2 magneto generator, 14mm gauge spark plugs
Lubrication forced with 3 oil pumps
Cooling watercooled with one centrifugla pump and one front radiator
Trasmission fixed drive shaft composed by two half shafts with central bearing
Clutch dry, steel and aluminium alloy multiple discs, elastic hub
Gearbox four speed + reverse gear, mated with differential housing, lateral shift
Gear ratio I 1:2.39
II 1:1.66
III 1:1.284
IV 1:1
R 1:2.30
Rear axle -
Differential ratio 16/38

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