CSF has over 5 decades of experience manufacturing radiators. So when it comes to keeping your engine cool and your Audi B5 S4 running at its best, a CSF High-Performance All-Aluminum Radiator is the obvious choice. Designed to perform on the street or at the track, a performance radiator is a must-have for both high horsepower builds as well as race vehicles which need added cooling performance in motorsports environments. This radiator features a 2-Row core with CSF's exclusive B-Tube Technology: Unlike a regular oval shape "O" type radiator tube, CSF uses a specially engineered tube in the shape of a "B". These "B-tubes" are carefully formed and then brazed over the seam to seal. CSF is able to use thinner and lighter aluminum material (with better cooling efficiency) because this design is actually stronger than normal "O" shape tubes that are welded. The design (inlet in the middle of the tube that is seam brazed) increases the heat transfer surface area of the tubes by approximately 15% over regular tubes - producing the efficiency of two smaller tubes vs. one large tube within the same space criteria. With "B-tubes" you are able to get "dual liquid laminar flow". CSF also uses ultra efficient multi louvered fins that are carefully and precisely aligned to maximize airflow through each radiator core. Fin specifications are carefully measured and calculated for each application, and tested for maximum heat rejection efficiency in our wind-tunnel lab. The CSF Audi B5 S4 radiator is a true "Drop-in fit" design requiring no modifications to install. OE style brackets are all CNC machined and welded for the best durability possible. Inlet/Outlet connections are designed to match the OE connections so you can reuse OEM hoses or aftermarket. Trust the cooling experts at CSF for the best performing, highest-quality, and most reliable radiators. Applications - 2000-2002 Audi S4 - Turbocharged 2.7L V6 (Manual)

OEM Part Numbers

- Audi: 8D0 121 251 AP

- Audi: 8D0-121-251-AP

- Audi: 8D0121251AP

- Audi: 8D0 121 251 AP VAG

- Audi: 8D0-121-251-AP-VAG

- Audi: 8D0121251APVAG