Wagner Tuning Audi S8 D4 4.0 BiTurbo Radiator Kit

Wagner Tuning Audi S8 D4 4.0 BiTurbo Radiator Kit

The Audi S8 D4 runs a 4.0-litre V8 twin-turbo engine with a clever but demanding cooling setup. Instead of cooling the charged air (the compressed air going into the engine) directly with outside air, it uses a dedicated water circuit to do the job. This is known as indirect charge air cooling. The radiator that the water circuit passes through is what this kit upgrades, and improving it has a direct, measurable effect on how the engine performs under load.

Wagner Tuning’s Competition Radiator Kit replaces the factory water cooler with a significantly larger unit, increasing radiator volume by 66% over the standard item. More volume means more heat can be pulled out of the cooling water, which keeps charge air temperatures lower. Cooler intake air helps the engine run more efficiently and hold its power output more consistently, which is especially useful during sustained hard driving where heat build-up is a known issue on these cars.

Why This Upgrade Makes a Difference

On a standard S8, the factory water cooler can become a limiting factor once the engine is working hard. As cooling water temperature climbs, charge air temperature climbs with it, and the ECU may pull timing or reduce boost to protect the engine. The result is a gradual drop in performance during spirited driving or track use. The larger Wagner cooler tackles this directly by keeping the cooling circuit running at a lower temperature for longer.

The core uses Wagner Tuning’s competition racing mesh, designed to balance internal and external cooling surface area. This maximises heat transfer without restricting airflow to surrounding components, which matters on the tightly packaged front end of the S8. The cooler is also finished with a thermally conductive anti-corrosion coating, helping it stay efficient and protected throughout its service life.

Kit Contents

• 1x Wagner Tuning competition water cooler
• Silicone hoses
• All necessary mounting hardware
• Detailed installation instructions

Installation Notes

The kit is supplied as a complete, ready-to-fit package. No cutting, fabrication, or specialist equipment is required. As with any cooling system work, care should be taken when draining and refilling the coolant circuit to avoid air locks. If you are not confident working with cooling systems, fitting by a qualified mechanic is recommended.

Vehicle Compatibility

This kit is designed for the Audi S8 D4 and related A8 variants fitted with the 4.0 TFSI V8 BiTurbo engine, including:

• Audi S8 D4 520PS / 382kW – 04/2012 to 09/2017
• Audi S8 D4 Plus 605PS / 445kW – 09/2015 to 09/2017
• Audi A8 4.0 TFSI D4 435PS / 320kW

Please use the vehicle lookup tool or check the Vehicle Fitment tab to confirm this kit is correct for your specific car before ordering.