BMW M3 G80 Hits 823 HP 

At Avon Tuning, we thrive on pushing the boundaries of automotive performance. Our latest R&D project focused on extracting the maximum potential from the formidable BMW M3 G80 with minimal hardware modifications. The G80 is powered by an S58 engine - a platform with heaps of potential. By integrating Flex-Fuel technology and applying our custom tuning, we’ve achieved extraordinary results that make this BMW M3 a special car to drive on both track & drag strip.

The BMW S58 engine is a high-performance inline-six turbocharged engine developed by BMW M GmbH. It's the successor to the formidable S55 engine, and it powers modern BMW M models like the G80 M3, G82 M4, and X3M/X4M. It’s built off the modular B58 engine platform but heavily revised for performance.

Key Specs of the S58: 

Engine type: 3.0L inline-6 twin-turbocharged (twin mono-scroll turbos)

Stock power: 480 PS (M3/M4) to 510 PS (Competition models)

Redline: 7200 RPM

Compression ratio: 9.3:1

Bore x Stroke: 84mm x 90mm

Fuel system: High-pressure direct injection (5,000+ PSI / 350 Bar)

Block: Closed-deck aluminium with forged internals

Cooling: Upgraded oil/water cooling for track reliability

Why Ethanol? The Future of High-Performance Fuel 

Ethanol, derived from renewable sources like corn or sugarcane, brings more than just sustainability to the table. With a naturally high octane rating, it allows for greater ignition timing and boost pressure, delivering more power. It’s also biodegradable and less toxic than traditional petrol - ideal for motorsport environments. 

However, ethanol comes with challenges, particularly its lower energy density, which demands more from the fuel system. Without proper tuning, simply pouring ethanol into your tank can harm performance or engine health. 

Cracking the ECU: Unlocking the S58 

The Bosch MG1CS024 ECU used in the G80 is one of the most secure on the market, featuring the latest Bosch protection which makes it impossible to modify with mainstream remapping equipment. The MG1CS024 boasts advanced encryption, secure bootloaders, and software locking mechanisms. These are deliberate security measures implemented by BMW and Bosch to prevent unauthorised access, both for tuning and anti-theft reasons. In order to unlock this ECU so that we can modify (remap) the internal memory with our equipment the ECU was sent to a company called Femto who are based in Finland. After a secure patch was applied, we installed BootMod3 to enable Flex-Fuel tuning and map switching. 

The process is as follows: 

1. Send the ECU to Femto to be unlocked.  
2. Install BootMod3 Tuning Platform. 
3. Avon Tuning engineers custom tune the car on the dyno 

The Rise of Flex-Fuel Tuning 

Thanks to advancements in ethanol sensors and ECU firmware, Flex-Fuel tuning has become a practical option for performance enthusiasts. Vehicles equipped with Flex-Fuel systems can run on varying blends of petrol and ethanol, with the ECU automatically adjusting performance parameters based on the detected ethanol content. 

For our BMW M3 G80 project, we installed a Flex-Fuel kit developed by Pro Tuning Freaks — creators of the renowned BootMod3 tuning platform. This hardware was seamlessly integrated into the vehicle’s CAN bus system, allowing real-time monitoring of ethanol content. 

Custom Tuning & Dyno Testing 

Our tuning journey began with a baseline dyno test using 97 RON pump fuel. We then custom-tuned both the ECU and TCU to optimise performance under various ethanol blends. Over several weeks, we tested blends from E15 to E65, gathering extensive data and fine-tuning each map. 

Here are the dyno results: 

We found E50 provided the sweet spot in terms of power gains before reaching the limits of the stock fuel system. To run ethanol blends over E50 upgrades to the fuel system would be required. 

We also implemented map switching, allowing the customer to switch to different maps depending on the requirement from the car.

Map 1: Full Power – Flex Fuel – Can run on Pump or Ethanol up to E50 – Designed for max power testing and drag racing.

Map 2: Track map – Super smooth and linear power – Pump fuel only – Perfect for circuit racing. 

Map 3: Stock map – Stock power – Pump fuel only – For calm days! 

Real-World Testing at Santa Pod 

Dyno figures are impressive, and the dyno is an incredibly useful tool for testing and checking power output, but it can’t replicate the exact loads and stresses a vehicle will be subjected to on track, especially when launching and during heavy acceleration. 

So, we transported the vehicle to Santa Pod Raceway in Northamptonshire and carried out multiple ¼ mile drag racing runs, giving us the opportunity to fine tune the ECU and TCU calibrations and also further test different blends of ethanol. The G80 ran a staggering 9.859-second quarter mile. This not only validated our dyno work but confirmed the car’s track-ready potential. 

Other Tuning Options 

• Stage 1 Plug & Play Module – Unlocks ~620 HP (no ECU unlock required) 
• Stage 2 Road Legal Package – Up to 680 HP with MOT-compliant mods 

What’s in the Avon Tuning G80 800+ HP Package?

For those ready to transform their G80 or G81 M3 into a true track-dominating monster, Avon Tuning has developed an off-road competition-only performance package designed to push the limits of what the platform can do. While developing this package, we tested several exhaust configurations to find the ideal balance between performance and sound. After careful consideration and multiple trials on the dyno and road, the customer opted for the full Milltek Turbo Back Exhaust System. Its unmatched flow characteristics and aggressive tone not only complemented the vehicle’s power gains but also delivered the visceral driving experience worthy of an 800+ HP M3.

Here's what's included in the 800+ horsepower upgrade package:

• A Ramair Cold Air Intake to improve airflow and deliver cooler, denser air to the turbochargers.
• A Milltek Turbo Back Exhaust System, complete with decat and OPF delete.
• A Flex Fuel Kit that enables the use of high-ethanol fuels and takes advantage of dynamic tuning capabilities.
• A full tank of Ethanol X98 Racing Fuel (38L)
• Femto ECU Unlock, allowing full access to the engine control unit for custom calibration.
• A BootMod3 License, unlocking advanced tuning and real-time map switching.
• A bespoke Avon Tuning Custom ECU & TCU Calibration
• An XHP Stage 3 TCU Tune
• Professional installation and dyno setup, completed by our experienced in-house technicians.

As Seen on Officially Gassed

This 800+ HP G80 M3 recently hit the spotlight in an episode of the hugely popular Officially Gassed YouTube series, where it went head-to-head against two serious contenders: a 700HP xDrive M140i and a 900HP M5.

In the video, the G80 showcases its full potential on the strip, thanks to the complete Avon Tuning performance package. From brutal launches to high-speed pulls, you’ll see exactly what this off-road competition setup is capable of.

Watch the full video below:

Conclusion: Finding the Balance of Power & Practicality

Our Flex-Fuel BMW M3 G80 project proves that maximum power and everyday usability can coexist. Whether you're chasing sub-10 second drag times or want to dominate a track day, this setup gives you the flexibility to fuel up and unleash performance on demand — without compromising drivability. 

To discuss tuning packages or book your BMW in for a consultation, contact Avon Tuning today.