Audi RS4/RS5 B8 Tuning Guide

The Audi RS4 and RS5 B8 are high-performance machines that come with a naturally aspirated 4.2-litre V8 engine. While these cars already provide thrilling performance, many owners look to enhance their driving experience through tuning. However, it’s important to remember that naturally aspirated engines, like the one in the RS4/RS5, don’t offer the same dramatic power increases as turbocharged or supercharged engines. That said, there are still significant gains to be had with the right upgrades, particularly in the areas of intake, exhaust, and engine management.

This guide outlines what to expect from a “Stage 1” and “Stage 2” tuning on the Audi RS4/RS5 B8 and provides details on the hardware needed for each stage.

Looking for performance parts for your RS4/RS5? Click here!

Stage 1 Tuning

Stage 1 tuning is the entry-level option for improving performance without significantly altering the car’s engine internals. It focuses on modifications that enhance the efficiency of the engine’s airflow and optimising the ECU to extract a bit more power. This stage is generally safe for daily use and doesn't usually require extensive changes to the vehicle.

Hardware Required for Stage 1:

• ECU Remap/Flash Tune - The most common and effective modification in Stage 1 tuning is an ECU remap or flash tune. This involves recalibrating the car’s engine control unit (ECU) to optimise air-fuel ratios, ignition timing, and throttle response. This can result in a modest increase in power, typically around 10-20 horsepower depending on the quality of the tune. Since the 4.2 V8 is naturally aspirated, the gains won’t be huge, but it can still improve throttle response and drivability.
• Cold Air Intake or High-Flow Air Filter - Replacing the factory air intake with a cold air intake or installing high-flow air filters allows the engine to breathe more easily by providing cooler, denser air. This helps with throttle response and may add a few horsepower, although the gains are relatively small on a naturally aspirated engine.
• Cat-back Exhaust System - A performance cat-back exhaust system can help improve the flow of exhaust gases, which reduces backpressure and enhances engine efficiency. While this modification won’t add huge power gains, it can improve the engine’s overall responsiveness and provide a more aggressive exhaust note. Expect modest power gains of around 5-10 horsepower.

Check out our Audi RS4/RS5 Intake options here
Check our Audi RS4/RS5 Exhaust systems here

Expected Gains from Stage 1:

• Power increase of 10-30 horsepower
• Improved throttle response
• Slightly enhanced exhaust sound

Stage 2 Tuning

Stage 2 tuning takes the performance upgrades a step further. This stage involves additional modifications that increase engine performance more noticeably. It typically requires a few more hardware upgrades and might involve more technical installation. Stage 2 can yield more significant gains but may require supporting modifications to ensure reliability.

Hardware Required for Stage 2:

• Full Exhaust System (Downpipes, Mid-pipes, and Cat-back) - Upgrading to a full exhaust system, including high-flow downpipes and mid-pipes, allows for better exhaust flow from the engine to the back of the car. This reduces restrictions and enhances performance. The removal of restrictive catalytic converters in the downpipes can lead to improved exhaust gas flow, offering a more significant power increase than a simple cat-back system. Gains can be in the region of 15-25 horsepower.
• Upgraded Intake Manifold - While the stock intake manifold is sufficient for most driving needs, upgrading to a larger, more efficient intake manifold can help improve the engine’s airflow, especially at higher RPMs. This can help with high-end power and allow the engine to breathe more freely, especially when paired with other performance mods.
• ECU Remap/Custom Tuning - Stage 2 tuning typically involves a more aggressive ECU remap or a custom tune. This is necessary to accommodate the increased airflow from the full exhaust system and upgraded intake components. A custom tune will adjust the air-fuel ratios, ignition timing, and throttle maps to maximise the gains from these new hardware components.
• Upgraded Air Filters - At Stage 2, a high-performance air filter or cold air intake is often used in combination with the intake manifold and exhaust upgrades. These air filters allow for improved airflow into the engine, which helps increase performance.
• Performance Cooling Systems (Optional but Recommended) - With increased performance, the engine and associated components will produce more heat. Adding an upgraded oil cooler or larger intercooler (if applicable) can help maintain optimal operating temperatures and ensure the engine performs consistently under load.

Expected Gains from Stage 2:

• Power increase of 30-50 horsepower
• Improved throttle response and engine efficiency
• Enhanced exhaust sound and more aggressive driving experience

Things to Consider Before Tuning Your RS4/RS5 B8

• Naturally Aspirated Engine Limitations
  As mentioned earlier, the 4.2 V8 engine in the RS4 and RS5 is naturally aspirated, meaning it won't deliver the dramatic power gains that you might get from turbocharging or supercharging. While Stage 1 and Stage 2 tuning can improve overall performance, the gains won’t be as extreme as those seen in turbocharged vehicles. It’s important to have realistic expectations when tuning.
• Reliability and Warranty
  Any modification or tuning can potentially affect your car’s reliability and may void the manufacturer’s warranty. Always consider the long-term effects and consult with a professional tuner to ensure that the upgrades you’re making are safe for your car.
• Supporting Mods for Stage 2
  As you increase the performance of your car, you should also consider upgrading the brakes, suspension, and tyres. Stage 2 tuning will likely result in more power and performance, so ensuring that your car can handle the increased power is important for both safety and performance.
• Fuel Requirements
  Higher performance engines may require higher-octane fuel to avoid knocking and ensure optimal combustion. Be prepared to use premium fuel after tuning, especially if you have significantly increased engine performance with Stage 2 mods.
• Costs and Professional Installation
  Tuning and performance modifications can add up, especially for Stage 2. Make sure you budget for the parts and consider professional installation to ensure everything is done correctly. A poor installation or incorrect tune could lead to issues that could compromise the performance and reliability of your car.

Conclusion

Tuning your Audi RS4 or RS5 B8 can be a rewarding way to enhance its performance and driving experience. Stage 1 tuning provides modest gains with minimal investment, focusing on the intake, exhaust, and ECU. Stage 2 tuning, on the other hand, offers more significant performance increases but requires additional hardware upgrades like a full exhaust system and upgraded intake components.

While tuning a naturally aspirated engine like the 4.2 V8 won’t give you the huge gains seen with turbocharged or supercharged setups, it still provides noticeable improvements in performance, sound, and throttle response. Always keep in mind the need for supporting mods and ensure that your car’s reliability and safety are not compromised in the process. Working with a professional tuner can help you achieve the best results while maintaining the integrity of your vehicle.