The Cobb AccessPort unleashes a continuous bombardment of information. The screen can be setup to display 6 live engine statistics with each showing min/max figures. This is just the surface; with the touch of a button, it’ll begin recording a variety of parameters of your choosing. That’s a lot of information that was previously inaccessible. What does this mean? What’s will this information tell me? I’m glad you asked!

One of the more fun things to do with all this data is to plot your own dyno curves based on full gear pulls! Do you know when your optimal shift points are? Is it worthwhile revving the engine deep into redline? Where could I gain time? When does my turbo really spool? What’s my baseline power? How much power was gained from the last mod or tune? Once you see the power curve, these questions are easily answered!

So let’s talk about V-Dyno. Just like an in-ground dynamometer it measures the force (torque) applied by the engine to accelerate your car. Let’s say you go out driving, it’s the middle of boost season, and the car is running like the prized thoroughbred it was built to be. Everything feels good, ear to ear smile, but then, what do you tell your buddies? My butt-dyno says I make 347WHP? They’ll laugh you out of the stable. Instead take a data log. Let V-Dyno crunch the numbers, and have a printout that your car is actually making 347WHP! If the datalogs you take are consistent (as described later in the article) and you setup your car’s parameters correctly, Vdyno can be very accurate and repeatable and we have correlated our results to in-ground dyno data.

So how does it all work?

V-dyno analyses engine speed (RPM) and calculates acceleration performance based on the rate of change of engine speed in a single gear. It factors in tire size, weight of the car, gear ratio, ambient air temperature and frontal area of your car and a number of other things such as occupant weight. You’ve probably heard “oh but that was power on such and such dyno so the numbers are skewed this and that way”. Well, that’s also built in. You can select your dyno type and correction factor. There’s a large amount of preset cars in their database but we’ve build a good profile for the VW GTI. You can build the same profile in your own installation of Vdyno using the information below.

How do I collect data?

First, the AP has to be setup to record all the useful parameters. For Vdyno you need to log at least AFR, Accelerator Pedal Position, Boost Pressure, and RPM. You can log others as well, but these are the ones that are used in the calculation. Then, while driving make sure you are in the Gauges screen. The car will need to be cruising in 3rd or 4th gear, around 2500 rpm. Click the center button to start recording. Wait a second until the screen on the AP starts refreshing again, and then stomp on the gas as if it were an on/off switch. Take it to redline, release the gas pedal, shift up, then click the center button again to stop recording. 

Your final results are only as good as the collected data. Here are a few hints to getting repeatable V-dyno results:

• Make sure it’s not windy
• Keep ambient temperatures consistent
• Always collect data on the same stretch of road
• Empty your trunk
• Don’t take passengers along
• Gas tank half full
• Do 2 or 3 passes
• 4th gear logs are better than 3rd
• Stay safe!!!

I have logs, now what?

Transfer them to your computer using the AccessPort manager. Download Virtual Dyno, and set it up with the correct profile for your car. Match the columns up. Then drag and drop the logs in, wait a second and you’ll see your power curve.

But my power curve looks strange.

There are a number of things that will skew the data and so the end result will be way off. If you see strange humps, bumps, and non smooth curves, chances are that the car lost traction, you had clutch slip, there was a big bump in the road or something else went wrong. If you come up with something odd and want to chat about your setup (and how to get more power) drop us a line!

Happy Vdyno-ing!

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.

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.

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.

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.

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!

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!