Product Description
BA-921 DETROIT AIR COMPRESSOR – 1 3/4" INLET, REMANUFACTURED
PART NUMBER(S):
Fleet Products: K031987X (Remanufactured) | OE: A4721300015, A4721300515, A4721300815
DESCRIPTION:
Model: BA-921 Twin-Cylinder
Vehicles: Detroit Diesel DD13/DD15 (2007 EPA) – Freightliner, Western Star, Cascadia
• Bore Diameter: 92.1 mm (3.62")
• Stroke: 56 mm (2.20")
• Swept Volume: 247 cm³
• Cooling: Water-cooled head, air-cooled crankcase
• Inlet Port: Top, 1 3/4" tube – no O-ring ear
• Air Discharge Port: Top
• Governor Port: 1/8"-27 NPT
• Coolant Ports: M18 x 1.5
• Exhaust Port: M26 x 1.5
• Crankshaft Thread: M20 x 1.5
• Operating Speed: Up to 3,000 RPM
• Mounting Style: Flange
• Core Group: 921G
• Configuration: Engine-driven, thru-drive support
Applications:
Direct replacement for factory-installed compressors on Detroit DD13 and DD15 EPA 2007 engines used in highway tractors, commercial haulers, and heavy-duty vocational trucks. The BA-921 model is ideal for maintaining reliable air supply in brake and auxiliary systems. Commonly used in Freightliner Cascadia and Western Star platforms.
CROSS-REFERENCE(S):
170.ACK031987, 710383AT, A4721300015, A4721300515, A4721300815, HDX K031987X, HDXK031987X, K020253, K020801, K031986, K031986SC, K031987, K095124, K095740
A cross-reference listing means this part should be a suitable replacement for the part numbers listed. Please confirm all ports and dimensions match your application before installing.
IMPORTANT INSTALLATION NOTES:
✔ Use only approved installation gaskets and torque all fasteners to OEM specifications
✔ Flush coolant and air lines before installation to prevent contamination
✔ Verify thru-drive alignment if used in pass-through accessory setups
✔ Replace governor and inspect oil lines for flow and blockage
✔ This unit includes the drive gear and is ready for immediate install
SOLD AS REMANUFACTURED – CORE RETURN REQUIRED
Built to OEM standards — thoroughly cleaned, inspected, and tested to ensure durability, performance, and reliability in demanding applications.
SUPPORT & ORDERING
For technical support, installation guidance, or to confirm fitment, call 1-877-243-0442 or email sales@fleet-products.com .
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