Wrapping up our coverage from TX2K12, one of the largest events in the country, we decided to write one last article. Given that the event has pushed beyond its original Toyota Supra roots to the highly acclaimed Nissan GT-R scene, we thought it would be fitting to do a feature article on the “GT-Rs of TX2K12.”
During our fact finding, we soon realized there were several prevailing themes that every shop addressed in one way or another through their builds. Before we get too deep into the tech specs for each featured shop’s build, let’s analyze these components and how they all fit together to make an amazing platform that is the R35 even better.
Due to the fuel’s propensity to prevent engine knock and predetonation along with its cooling properties, nearly all the shops being featured are running E85 on their builds. Without diving into the details about the advantages and disadvantages of the miracle fuel (save that for another day!), we must address the matter that E85 has a stoichiometry ratio lower than that of gasoline. Huh? It means that it takes about 30% more E85 to achieve the proper air/fuel ratio for combustion compared with standard petrol fuel. This fact requires a build to incorporate a larger delivery system to handle the increased requirements, including larger injectors and bigger (if not more) fuel pumps. With the prevailing theme of a fully street-legal, weekend-warrior build, one must also remember that E85 is only readily available in certain parts of the country, and that an appropriate engine management tune must be used.
Getting your hands on an upgraded tune is sometimes easier said than done. Good thing that COBB Tuning has stepped forward and provided a fully capable engine management tuning platform for the R35. COBB Tuning’s AccessPORT has proven to be a favorite among our featured shops, as every one of them has chosen it for their R35 tuning solution. While we will provide a much more in-depth look later on, the AccessPORT serves as an interface to communicate and reflash the stock engine management software that these vehicles come with. With some limitations, this allows the respective in-house tuners to alter engine management software (tune) specifically for their build specifications to optimize air/fuel ratios and ignition timing.
Stock Engine Management System Limitations
While the important ECU’s function can be managed through the AccessPORT (e.g., air/fuel ratios and ignition timing), certain limitations prevent desirable functionality under certain circumstances. Specifically speaking, the GT-R’s fuel management system is notorious for limiting delivery at launch. While the stock system allows for a launch at 4,000 RPMs, it actually does this by limiting the throttle body and not by ignition cut, thus preventing the engine’s twin turbos from providing boost at such a critical moment. By limiting the RPMs via the throttle body, it limits the amount of load on the engine and turbos, thus preventing boost from being created.
It’s no secret that the biggest issue with the R35 is its inability to get off the line. In the world of drag where the 60-ft. ET is everything, it’s necessary to get as much torque at the low end right off the line as possible. This is where some of the shops are utilizing a standalone engine management system, known as ProEFI (in conjunction to COBB’s AccessPORT), to bypass the stock software and build boost at launch by means of ignition cut, which is also known as TwoStep Launch Control. With these elements of the build dialed in, focus must be directed to delivering power to the wheels.
Launch Control & the Transmission
To dependably deliver this increased power to the ground, an extremely robust transmission and launch control system is required. All teams have acknowledged the transmission’s shortcomings and are trying to solve the problem, which includes upgrading the dual-clutch system, replacing the gear-sets, seals, transmission coolers, and more.
Getting power to the wheels without obliterating gears is one thing. Actually hooking up at launch by finding the most effective combination of power to the right places is another. By utilizing Nissan’s ATTESA-ETS system, the GT-R uses electronic sensors and hydraulically actuated clutches to manage traction. When slip is detected, the system directs power to the portion of the system with the most traction. The ATTESA system is able to not only direct torque to the front or back wheels but can also split the torque between the rear left and right wheels as well. This works in conjunction with the Transmission Control Unit’s Launch Control software, which allows the car to hold a certain RPM and electronically manages clutch engagement to allow for a quick off-the-line start.
Another great function of the COBB AccessPORT is being able to upgrade older versions of the launch control software to the latest and greatest iteration. This allows the shops to maximize the potential of all components that define the build. By combining upgraded Launch Control software with the earlier mentioned ProEFI system and the superior traction control functionality, we’re starting to see some real power off the line.
Another great function of the COBB AccessPORT is the ability to upgrade older versions of the launch control software to the latest and greatest iteration. This provides the shops with the ability to maximize the potential of all components that define the build. By combining upgraded Launch Control software with the earlier mentioned ProEFI system and the superior traction control functionality, we’re starting to see some real power off the line.
All these separate components meshed together are helping the industry’s top tuners achieve new goals, records, and notoriety. In next week’s article, we will be featuring top tuners, such as AMS Performance, Switzer, Jotech, T1 Race Development, COBB Tuning, and more. Stay tuned for the GT-Rs of TX2K12 Part 2!