The latest version of Scion's tC sport coupe was released to aftermarket manufacturers for testing in early October 2010. this launch date almost immediately preceded our industry's largest trade show (the SEMA Show in Las Vegas held during the first full week of November). Since the Sema Show is where the latest vehicle platforms and aftermarket goods converge, GReddy picked this event to reveal its prototype turbo kit for the new 2011 Scion tC. Since the thirty-day window between receiving the vehicle and attending the show was not enough time for a proper product research, development and testing cycle, GReddy finished the prototype turbo system, but not the engine manegement solution that will be accompanying the actual production system that is scheduled for release in the Spring of 2011.

TARGET PRACTICE

For the Research and Development Department at GReddy, one of the most important facets of producing a bolt-on turbo kit involves estimating a target horsepower output goal. GReddy believes that the actual production output of its turbo kit also needs additional headroom for the enthusiast who will use the kit as a starting point, not the ending point, of their particular build. For example, if GReddy sells a turbo system that bolts-on an engine and raised horsepower from 200 to 300 horsepower, that same system may be able to run at higher boost levels to produce 400-to-450 horsepower with the proper mix of parts. For the 2011 Scion tC platform, GReddy took into consideration the larger motor and sportier nature of the second generation tC. With that in mind, a target production horsepower output of 300 horsepower was set. This represents a full 40 horsepower over the rated output of their turbo kit for the first generation tC.

Of course the centerpiece for any turbo system is the turbocharger itself. Every turbocharger has its own performance signature and personality. Since there are seemingly endless combinations of turbocharger frame, turbine wheels, compressor wheels and compressor housings, GReddy has taken this knowledge and created a database of, essentially, what will and won't work, and how well it will work, for any given platform.

This experience led to selecting the TD06/TD07 hybrid-based turbo housing currently used in the prototype kit. The prototype T67-25G is not the biggest and baddest turbo they could shoehorn into the engine bay, but it is the biggest of a series of custom trims that GReddy determined would meet its performance criteria with room to spare. Development with the T67-25G will likely size the turbo downwards based on real world performance and the desired response characteristics for the production turbo system. However, the T67-25G offers the best starting point as any smaller housings will fit in without introducing interference problems with existing OE components (like air conditioning).

COOL UNDER PRESSURE

Years of experience in aftermarket turbocharging and turbocharger upgrades has taught GReddy R&D that, in addition to a properly sized turbocharger, the proper manifold design has a great impact on how the turbocharger performs. Manifold design can affect final max power output, transient response, spooling time, and lower and mid-range characteristics. Mike Chung, Planning Manager for GReddy, states, "Once the turbo is positioned and the routing of the downpipe, wastegate, charge piping, suction piping and oil lines are figured out, we build several prototype manifolds." The manifold on display for SEMA was a prototype Header-Type SUS manifold. Chung is quick to note, "Depending on how testing goes, we may go with a different style manifold." End-user cost, long-term reliability and how the kit in its final form is desired to perform will all come into play before the pieces are boxed and sold as a kit. "This is where we are now in the testing of our turbo kit," Chung adds. "Our development provides a huge benefit to the final customer; all the turbo sizing and trial and error is done before you purchase a kit."