How about this beauty. 7 bank,42 cylinder diesel. Some germans use it for tractor pulling,making around 8000hp.
General characteristics
Type: 42-cylinder Liquid cooled 7 bank, 6 cylinder per bank diesel radial engine
Bore: 160 mm (6.29 in)
Stroke: 170 mm (6.69 in)
Displacement: 143.6 L (8,763 in³)
Length: 3700 mm (145.66 in)
Diameter: 1560 mm (61.41 in)
Dry weight: 5450 kg (12,015 lb) (dry)
Components
Valvetrain: 7 overhead cam shafts, one per bank.
Fuel type: Diesel fuel
Cooling system: Liquid-cooled
Performance
Power output: 3,942 hp (2,940 kW, 3,997 PS) at 2,200 rpm
Specific power: 20.47 kW/L (0.44 hp/in³)
Power-to-weight ratio: 0.53 kW/kg (0.32 hp/lb)
Zvezda M503 (The name)