COBB Tuning is proud to announce the immediate availability of our proprietary Speed Density (SD) tuning solution for all currently-supported 2.5L USDM turbocharged Subaru vehicles! This capability is available as a free update to our AccessTUNER Pro software and AccessPORT firmware. Our implementation of Speed Density adds our proprietary tuning logic to the factory ECU, enabling it to calculate load, ignition and fueling requirements using the engine’s manifold absolute pressure (MAP) sensor, instead of the factory mass airflow (MAF) sensor. COBB Tuning’s exclusive Realtime tuning capabilities and Hybrid Logic (active switching between MAP and MAF based logic) make this a uniquely powerful and flexible engine management solution. Read on for more details about the work COBB Tuning is doing to make sure the AccessPORT is the most comprehensive OEM ECU tuning solution available for Subaru performance enthusiasts.

Why Speed Density
The most basic function of an engine control unit (ECU) is to measure airflow and its translation to engine load. Precise and consistent load calculations along with feedback from other critical sensors allow the ECU to accurately control ignition timing, variable camshafts, and fuel delivery. The most common way to measure load in modern vehicles is with a MAF sensor. Vehicles with stock engines and mild upgrades can utilize the MAF sensor with excellent overall results. However, in big-build and motorsports applications where power levels are extremely high and intake airflow configurations are less standardized, the use of a MAF sensor can be limiting.

Speed Density tuning using the Subaru factory ECU is a major break-through for high-power Subaru builds. High-power builds using the OEM MAF sensor require very large MAF intake housings to keep the MAF sensor within its usable range, which introduces reduced resolution and unpredictable turbulence that can affect tunability and drivability. Eliminating the need for a very large, high-quality MAF intake housing using Speed Density tuning logic allows for more flexibility when designing a turbo kit and the associated piping and plumbing. Speed Density tuning gives precise control over fueling, timing and other critical tuning components necessary to properly calibrate the vehicle at the very high power levels that today’s big Subaru builds are capable of producing.

Hybrid Logic – Ultimate Flexibility
The Speed Density update for AccessTUNER Pro software offers multiple ECU control modes to give the professional tuner and AccessPORT user a wider choice of engine modifications and tuning options. The software can program the ECU to run in the traditional pure MAF mode, a pure “Speed Density” mode, or a Hybrid Mode which uses both MAF and “Speed Density” with dynamic logic switching between the two.

Ease of Conversion
In order to make the transition to Speed Density as painless as possible, COBB Tuning has streamlined the process within the AccessTUNER software. Simply open an existing MAF-based calibration using the new Speed Density enabled software and resave the map. All of the tables from the MAF-based calibration will be loaded into the Speed Density based calibration. You are now ready to start tuning the Volumetric Efficiency (VE) table without the need of starting a new calibration from scratch!

Proven Performance
COBB Tuning’s Speed Density for 2.5L Subarus has already proven capable of tuning big-power Subaru engines. The LIC Motorsports 2004 Subaru STI Time Attack race car claimed the Modified AWD class victory and set a new Modified AWD class record at the Infineon Raceway Global Time Attack 2011 season finale using the AccessPORT and Speed Density tuning. More information about this performance and in-car action can be seen HERE.

Speed Density Availability
This initial release of Speed Density is available for professional tuning shops using AccessTUNER Pro software for turbocharged Subaru USDM vehicles. Speed Density for AccessTUNER Race is currently in development and will be made available to self-tuners once development and testing is completed. “Off-The-Shelf” maps will not be made available for Speed Density as custom calibration specific to each vehicle is required.

Currently, the following USDM 2.5L turbocharged Subaru vehicles are supported:

• 2008-2012 STI
• 2004-2007 STI
• 2008-2012 WRX
• 2006-2007 WRX
• 2007-2011 Forester XT
• 2004-2006 Forester XT
• 2007-2011 Legacy GT
• 2005-2006 Legacy GT
• 2009 Impreza GT / 2.5GT

We are in the process of investigating the feasibility of implementing Speed Density on 2.0L turbocharged Subaru vehicles. More information on this will be available soon.

To have your vehicle tuned using Speed Density logic, simply follow these steps:

• Contact your preferred ProTUNER, confirm they have the latest Speed Density enabled AccessTUNER Pro software and schedule a Speed Density dyno-tune appointment with them.
• Update your AccessPORT firmware to version 1.6.4.0-3162 (or later) prior to your scheduled tuning appointment. To update your firmware follow this Step-By-Step AccessPORT Firmware Update Tutorial.

It took us quite a bit longer than anticipated to develop Speed Density for all USDM 2.5L turbocharged Subaru vehicles, but now that it is complete, we are very excited about this release. We have combined our proprietary Speed Density logic with the flexibility of Hybrid Mode dynamic logic switching, the convenience of the AccessPORT’s Realtime tuning capabilities and the sophistication inherent in the factory ECU, bringing a powerful and unique solution to meet a large and long-standing demand in the Subaru enthusiast community. We would like to thank you for your patience and want to hear your feedback regarding Speed Density on your Subaru!

To learn more about our implementation of Speed Density, please download the Subaru 2.5L Speed Density Tuning Guide. If you are interested in becoming a new Subaru ProTUNER capable of tuning customer vehicles with Speed Density, please give us a call at 866-922-3059.