Tuning the MK6 GTI: Stg 1, E85, Limits and Findings

We have been tuning the MK6 GTI using the COBB AccessPort and working with a bone stock vehicle to start. It is a 2011 3 door DSG model. The car is very pleasant to drive and the first step to improving the experience is to add power safely and improve driveability.Stratified AccessPort COBB Mk6 GTI Tune

With a bone stock car (what is known as Stage 1) which just includes a reflash of the ECU you can get the majority of the power that the stock turbocharger can offer from just the tune. We started by ramping up performance from stock by adjusting boost, timing, and watching all vital engine parameters such as knock, air fuel ratios, charge air, and engine temperatures. A lot of seat time and stress testing of the calibration backs up its resilience. The car drives as stock until pushed and when it is pushed it delivers a smooth rush of torque that doesn’t fall flat in the upper RPMs.

On 91 octane fuel we were able to add a peak of 32whp and 69 ft-lb of torque over stock and 24whp and 48 ft-lb of torque over the COBB OTS tunes. The overall area under the curve gained however is what makes the car very enjoyable to drive.Stock VS COBB Vs Stratified Stg1

The torque ramp from low in the RPM range makes the car quite eager to accelerate and makes passing a breeze. The engine is not very knock prone which is great to see and even on 91 octane fuel we were able to achieve very consistent results.

Before adding any bolt-ons we decided to increase the fuel octane and search for what we can achieve with an E85 blend. Often an E85 blend and tune will net a very nice power increase. With the COBB AP it is also a breeze to switch between different fuel blends and tunes within minutes.

On most direct injection cars, blending some E85 with premium pump gas fuel allows you to tune very close to MBT (mean best torque) and maximize both boost and timing (especially on a stock turbo). For this, we strapped the GTI down on the dyno and mixed 4 gallons of E85 with E10 91 pump gas fuel.Stratified Mk6 GTI Tune

This achieved an E30 fuel blend. On this blend approximately 10% extra fuel volume must be delivered and both the high pressure fuel pump, low pressure fuel pump, and injectors are up to the task of delivering the needed fuel on the OEM turbo.

With the E30 blend we were able to achieve an additional 15whp and 26wtq on the bone stock car.

VW GTI E85 Stg1 vs 91 Stg 1

Boost was maintained at similar levels but we were able to push timing to mean best torque (MBT) meaning that we were able to add timing until we did not gain any further performance while remaining knock free.

At these power levels we are actually leaving some torque on the table between 2700 and 4000 RPM and this is why boost levels remained similar. This is because we have reached the programmed torque limit for the DSG transmission in our test car. This torque limit is set to 350nm and you can see that we are riding this limit in the graph below. The turbo is able to supply more boost and in order to achieve higher torque values in the lower RPMs, a DSG reflash is needed (and coming shortly). The DSG hardware is able to handle the extra torque; we just need to program it as such!

Torque Limit Reached VW GTI DSG

Even without a DSG flash, the car has a lot of potential with just an ECU tune. Adding flow parts will give us some top end performance and we will see an even flatter torque curve. As we continue to develop for the GTI and have applied our years of direct injection tuning expertise, we are now offering pump gas as well as E85 tunes for the MK6 GTI which can either be packaged with a COBB Accessport or bought individually. We are also going to continue updating you on our development and tuning progress. If you have any questions, don’t hesitate to Contact Us!