CSF Audi B5 S4 High-Performance Radiator

Introduced back in 1997, the Audi B5 S4 came stock with a 2.7L twin-turbo V6 pushing out a baseline of 250hp and 258lb-ft of torque, and remains a genuine sleeper favourite among track enthusiasts. A simple tune and a few basic bolt-on parts can easily add on 100hp, making bigger turbos and other high-performance upgrades a popular path on this platform. But adding power also means adding heat, and until CSF developed this radiator, there hadn't been a reliable, drop-in fit option at an acceptable price point available on the market.

These cars are now 20-plus years old, and if you haven't already had to replace the original plastic tank radiator, the time is genuinely coming soon regardless of how the car is driven. CSF's answer is a 2-row, 42mm core in a triple-pass configuration, using CSF's exclusive B-Tube technology to increase heat transfer by approximately 15% over regular oval welded tubes. The triple-pass design allows coolant to flow through the core three times rather than just once, letting much colder ambient air exchange heat with the coolant for three times longer and generating the lowest achievable outlet temperature. Super-efficient multi-louvered fins maximise airflow through the core, and exceptionally cut aluminium brackets with CNC-machined fittings make for a genuinely precise fit. This is a true drop-in fit requiring no modifications to install, with OE-matching inlet/outlet connections so you can reuse factory or aftermarket hoses.

Works with: OEM mounting points and hose connections. Manual transmission vehicles.

Why Choose This Radiator

• Genuine triple-pass flow structure, coolant crosses the core three times for the lowest outlet temperature
• CSF's exclusive B-Tube technology, approximately 15% more heat transfer than regular tubes
• Answers a genuine gap in the market, no reliable drop-in aftermarket option previously existed at this price point
• CNC-machined brackets and fittings for a precise, durable fit
• 100% all-aluminium, TIG-welded construction, a real upgrade over the ageing factory plastic tank design
• True drop-in fit, no modifications required, reuses OE or aftermarket hoses

Compatibility

• Audi S4 (B5, 1997-2002, 2.7L Twin-Turbo V6, manual transmission)

Note: confirm automatic transmission compatibility with your supplier before listing, as sourcing specifically references manual transmission fitment for this part.