If you’re looking to modify, upgrade, or simply keep up with the maintenance on an Audi B5 S4, upgrading the cooling system with new CSF’s high-performance all-aluminum radiator is highly recommended. It’s another crucial fix along with a laundry list of other items to replace and maintain on the iconic Audi B5 S4. Keep in mind that these cars are over 20 years old, and if you haven’t already had to replace your original plastic tank radiator, the time is definitely coming soon.
Introduced all the way back in 1997, the Audi B5 S4 came stock with a 2.7L twin-turbo V6 engine pushing out a baseline of 250 hp and 258 lb-ft torque. A simple tune and a few basic bolt-on parts can easily add on 100 hp to one of Audi’s most iconic sports cars that have become a favorite for track guys. The B5 S4 is definitely a sleeper and by slapping on bigger turbos, plus a few other high-performance upgrades, you’ll definitely catch some people off guard. However, adding additional power also means the creation of more heat in the engine. This is when you need to get a high-performance all-aluminum radiator for your Audi B5 S4.
Features
KEY FEATURES
- 2-Row 42mm Core (Dual Core) Featuring CSF’s Exclusive B-Tube Technology
- Core Features an Ultra-Efficient Fin with 6.5mm Fin Height and Multi-Louvered Design for Maximum Surface Area Contact
- CNC Machined "Quick-Connect" Inlet/Outlet Connections
- CNC Machined Brackets and Fittings for Superb Fit and Durability
- All-Aluminum Race Style Drain Plug
- Smooth Satin Finish
- "Drop-in Fit" Requiring No Modifications to Install - Accepts All Attaching OEM Components Including "Quick Connect" Hoses, AC Condenser, Mounting Brackets and Fan Shroud
CORE DESIGN
Product Description Sections
DESIGN & ENGINEERING
All CSF’s high-performance all-aluminum radiators include CSF’s exclusive B-Tube technology that increases the heat transfer approximately 15% over regular oval welded tubes. In addition, the super-efficient multi-louvered fins maximize airflow through the radiator core for the best radiator core technology and performance in the market. Combined with CSF’s industry-leading triple-pass design, CSF’s new Audi B5 S4 radiator is sure to check off all the boxes for the high performance and race crowd who need an upgrade in the cooling department. The radiator also features a smooth satin finish for a clean OEM+ look.
CSF’s triple-pass technology allows the coolant to flow through the radiator core 3x rather than just flowing across the surface of the core once. This allows much colder ambient air to exchange heat with the coolant for a 3x longer period of time generating the lowest outlet temperature possible. Still with a drop-in fit!
After studying what was currently available on the market for the Audi B5 S4 platform - CSF spent quite a bit of time perfecting the design after the initial prototype. CSF made sure to include machined OEM-style "Quick-Connect" inlet/outlet fittings, as well as machined installation seating areas on the top of each tank that holds the rubber bushing pads for correct and study fitment with no vibrations and no modifications necessary to install. Just another extra step that CSF has taken to continue to make the best cooling products in the world.
Perfectly positioned machined seating brackets for easy installation. The OEM style machined quick-connect fittings are also shown here.
Fitment Notes
REPLACES OEM PART NUMBERS
8D0121251AP, 8D0121251APVAG
WARRANTY
Limited warranty, 2 years, covering CSF High-Performance Cooling Systems under normal use and service (original purchaser).
FITMENT NOTES
Please note this radiator only replaces the OE 8D0-121-251-AP for Manual Transmission B5 S4 models. Some Manual Transmission models use the OE 8D0-121-251-BD which has a built in Transmission Oil Cooler. If your B5 S4 MT has a transmission oil cooler this radiator will not work as a drop-in fit replacement. You would need to run an external transmission oil cooler or delete your manual transmission oil cooler for it to work correctly.
Audi 8D0-121-251-AP (CSF #7071 Replaces this radiator)
Audi 8D0-121-251-BD
Vehicle Compatibility
What’s Included
- 1x CSF Radiator
Availability & Shipping
In stock and ships from a US warehouse, typically within 1–3 business days. Standard Shipping applies to every order — rates are calculated at checkout, with tracking provided once your order ships. Some items may require additional processing time depending on the specific product and current demand. Track your order any time at eurospeed.co/pages/track for a live delivery estimate.
Delivery time depends on the product. Most in-stock parts ship within days, while carbon fiber and made-to-order items may require production time before they ship. For the specific timeline on any item, check the Availability & Shipping section on that product’s own page — the guide below covers our general shipping types.
Shipping Overview
Depending on the item, free air freight may be available for select carbon fiber components, with estimated shipping around 1–2 weeks after dispatch. Larger hoods, oversized body components, and certain made-to-order items may require sea freight and longer delivery windows. If timing is important, please contact us at support@eurospeed.co before placing your order.
Shipping Coverage
EuroSpeed ships to customers across the United States and internationally. Shipping is included in the price of eligible products for your convenience and covers the initial cost of delivery to your destination.
Import duties, taxes, clearance fees, or customs charges required by your destination country are not included and remain the recipient’s responsibility.
Order Processing & Fulfillment
Every order is reviewed, processed, and prepared before shipment. Most in-stock products are processed within 1–3 business days, though some orders may take up to 5 business days depending on fulfillment location, product type, order volume, or courier pickup timing.
EuroSpeed stocks select high-demand products at our U.S. facility and international fulfillment centers. Because our catalog includes many vehicle-specific and specialty parts, not every product is held in-house at all times.
Some orders may ship through our trusted fulfillment network, which may include verified manufacturing partners, authorized distributors, regional warehouses, and international fulfillment centers.
- Orders may ship from a U.S. warehouse, international warehouse, manufacturer, or authorized fulfillment partner.
- Some products may require additional handling, processing, production, or quality-check time before shipment.
- Orders enter fulfillment shortly after being placed and may no longer be eligible for cancellation once processing, production, or shipment preparation begins.
Custom, Made-To-Order & Oversized Items
Custom, made-to-order, and oversized product categories may include carbon fiber steering wheels, hoods, trunk lids, fenders, front lips, splitters, side skirts, diffusers, bumpers, body kits, widebody components, select spoilers, rear wings, and other large carbon fiber components.
Many carbon fiber items are made to order. Some products may already be stocked and ready to dispatch when available, but if inventory is unavailable, your purchase reserves the next available production slot instead of waiting for a separate restock listing.
Production time: Production can take 1–4 weeks depending on product type, selected options, finish, current queue, and quality-control timing.
Shipping time: Shipping can take 2–10 weeks depending on item size, freight method, destination, customs processing, carrier delays, warehouse transfers, and final delivery location. Carbon fiber steering wheels typically ship faster, with shipping usually taking 3–7 business days after dispatch.
By purchasing custom, made-to-order, or oversized items, you acknowledge and accept the extended production, fulfillment, and shipping timelines associated with these products.
Tracking Updates & Delays
All orders receive a tracking number once generated by the courier. Tracking may take 2–3 business days after dispatch to show movement in the courier’s system.
Certain international, oversized, or freight shipments may show limited updates during transfer between fulfillment locations, warehouses, customs, or final-mile carriers. In some cases, tracking is provided or begins updating once the item reaches a regional warehouse, local carrier, or final delivery network.
Shipping timelines are estimates and are not guaranteed. Delays caused by high order volume, weather conditions, customs inspections, carrier disruptions, production queues, warehouse transfers, holidays, or other external factors may occur and are outside of EuroSpeed’s direct control. These delays do not qualify for cancellations or refunds unless the carrier officially marks the package as lost.
Delivery Responsibility
Upon delivery, carefully inspect the item for visible defects or damage before signing for it. If the item is damaged or not as expected, do not accept the package. Once a damaged or defective product is accepted, EuroSpeed cannot cover return shipping costs.
EuroSpeed is not liable for packages marked as delivered by the carrier. If a package is lost, stolen, or missing after being marked as delivered, the customer must file a claim directly with the shipping carrier. Our team will assist with available documentation when needed.
Shipping addresses typically cannot be changed once an order has been marked as shipped. If an address change is possible through the carrier, any carrier redirect, correction, or address-change fee will be the customer’s responsibility.
Please ensure your shipping address is entered correctly at checkout. Orders shipped to incorrectly provided addresses are the customer’s responsibility. EuroSpeed is not responsible for failed deliveries, additional shipping costs, lost packages, or refunds caused by incorrect shipping information, failure to accept delivery, or failure to collect a package from the post office or carrier pickup location within the required time frame.
Customs, Duties & Import Fees
EuroSpeed’s free shipping policy does not include import fees, taxes, duties, clearance charges, or other fees required by your destination country. These charges are the responsibility of the recipient, and EuroSpeed is not responsible for any duties or taxes requested by local customs.
Most shipments clear customs automatically through the shipping provider. However, if additional information is needed to complete the process, our team will assist where possible to help ensure a smooth resolution.
If customs clearance fails and the item is returned or destroyed:
- EuroSpeed reserves the right to deny refund claims.
- Returned items may incur return shipping fees, which will be deducted from any eligible refund.
- Items deemed too costly to return may be destroyed, and no refund will be issued if this occurs.
Package Protection
For added peace of mind, EuroSpeed offers ShipInsure package protection as an optional service at checkout. When selected, this service provides coverage for lost or damaged packages. EuroSpeed is not responsible for shipping delays, lost packages, or damaged items if purchase protection is not selected during checkout.
- Protects against lost or damaged packages.
- Must be selected at checkout.
- Not all oversized body kit purchases are eligible. Please contact us before ordering if custom insurance arrangements are needed.
To file a claim, please visit our Claims Center.
- Claims must be filed within 14 days of delivery.
- Packages stuck in transit for 14 days are considered lost.
- Damage claims typically require photo evidence.
- A 2-day buffer after delivery may apply before lost or stolen claims can proceed.
- Police reports may be required for orders over $500 or where fraud is suspected.
- “Damaged” means the item is broken and unusable.
Questions?
For questions about your order, shipping timeline, customs clearance, or delivery status, please contact our team at support@eurospeed.co. We’re here to help.
Product Installation & Use Disclaimer
EuroSpeed is not liable for any damages, injuries, fitment issues, installation issues, or vehicle-related problems resulting from the installation, modification, misuse, or use of our products.
Products should be installed carefully and used only as intended. For complex installations, electrical components, performance parts, body components, or products requiring modification, professional installation is recommended to help ensure proper fitment, function, and safety.
Any damage caused by improper installation, misuse, modification, or failure to follow installation requirements is the sole responsibility of the customer. By purchasing, installing, or using this product, you acknowledge and accept all associated risks.