Greg’s Audi RS3 is a very unique one. Not only does the owner race it, he also wanted a special modification for it: To use E85 instead of gasoline. E85 offers many advantages over traditional fuel types because of its cooling and anti-knock properties. For racing, it seems like the obvious fuel choice.
However, because this had never been done before, there was little information on whether the stock fueling system could cope with the extra flow required to run E85. An upgraded high pressure fuel pump was installed to help. The general rule is that fuel types containing high concentrations of ethanol are only suitable for vehicles that have been specifically designed or tuned for it. The use of Ethanol in vehicles not designed for it will cause drivability problems and damage to non-compatible fuel system components.
The car was delivered to us with a stock tune and managed 218kw at the wheels measured as 4wd on 98ron fuel.
Upgrade specifications
- Etuners custom Stage2 ECU remap for E85
- Upgraded exhaust system by Rob Bliss Exhaust
- Upgraded high pressure fuel pump for the Audi RS3 8V, Autotech
- Upgraded intercooler – HG Motorsport
Greg’s Audi RS3 8V 2.5 TFSI with a custom Etuners Stage2 ECU remap for E85
Using E85 as the main fuel type instead of 98RON gasoline
E85 offers a genuine alternative to petroleum based fuels for vehicles that are designed to use it. In many countries, like Australia, it is available straight from the pump at gas stations. The octane rating of E85 is around 113 RON (Research Octane Number) or in the region of 105 octane, but when combined with its cooling properties, the actual knock resistance of E85 is much higher than the octane rating suggest. This type of fuel consist of 85% ethanol and 15% gasoline, has about 26% less energy content than petrol. So compared to petrol, more fuel will be used to travel the same distance, approximately 30% more.
The tuner’s job is to adjust everything that has to do with fuel and injection in the ECU, together with ignition so that E85 can be used instead of 98RON. E85 has a very high latent heat of evaporation meaning when it goes through a phase change of liquid to gas, it absorbs a lot of heat. Therefore, it is a slow burning fuel and drops combustion temperatures significantly over 98RON gasoline. Special care must be taken for cold start and warm-up mode, as this type of fuel does not behave very well when the engine is cold.
Greg’s Audi RS3 8V 2.5 TFSI with a custom Etuners Stage2 ECU remap for E85
After a good session of custom tuning on the dyno, the RS3 picked up 60kW/80whp of maximum horsepower at the wheels, but most impressive was gaining 92kW/123whp in the midrange. The massive torque gains make this car completely transform on the track.
Performance results
- Maximum power at the wheels: 277.9kW / 375whp (measured stock 218kW / 292whp), gains 60kW/80.4whp
Greg’s Audi RS3 8V 2.5 TFSI with a custom Etuners Stage2 ECU remap for E85 – dyno results over stock
Comparing this to a facelift RS3 8V
Out of curiosity, we compared the result with a facelift RS3 Stage2 that had just been measured on the dyno. Facelift RS3 8Vs come with a bigger turbo and produce more power as stock and tuned compared to pre facelift models. A stage2 pre-facelift generally produces about 250kW, while a stage2 on a facelift generally makes 280kW.
The results were very interesting:
RS3 8V MY2017 (DAZA) stage2 in green, showing 285kW max power, but peak torque of 490Nm.
RS3 8V MY2015 stage2 with E85 in red, showing 277.9 kW max power, but peak torque of 520Nm.
All in all, these two cars were very close power-wise!
Many thanks to Greg for trusting us with his beautiful RS3. We cannot wait to see it race!
Greg’s Audi RS3 8V with Etuners stage2 E85
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