Detroit BA-921/922

BA-921 1 Piston 92mm NO Rod Bearings # Begin with 501, K0, and BA-922 2 Pistons 92mm NO Rod Bearings # Begin with 501, K0, 15.8 CFM and 31.6 CFM air compressors for Detroit Diesel engines are OEM-grade units designed for consistent pressure output, brake system durability, and long-haul fleet performance. A proven solution for heavy-duty brake air support. Standard BA-921 heads use a 4-bolt pattern and can be aluminum or cast iron, while Closed Room BA-921 heads use a 6-bolt aluminum head with a different matching gasket, cooling plate, and valve plate set. Although both are water-cooled designs, the Closed Room version has a different casting and different port and hardware layout for air, coolant, governor, and safety valve connections. The two head styles are not interchangeable.