Of course, the '11 Mustangs pack a new, more powerful powertrain control module to take on the additional duty of controlling the Twin Independent Variable Cam Timing on the four-cam engine. Essentially, there's a lot more going on in the head of the new Mustang, but tuners, like Justin, have taken to it quite readily.
"The overall function of the new Copperhead PCM is similar to the old PCMs, but with some important changes. The addition of dual factory wideband O2 sensors and full-time, closed-loop operation has made the PCM more capable of dealing with changes," Justin explained. "Some may see it as easier to tune due to the factory widebands, which can trick you into thinking you're tune is close (since they constantly correct air/fuel), but in reality a proper tune is still needed. There are many changes to the logic in the PCM, so the old rules no longer apply. Overall I would say having a good tuner is now more important than ever."
"The 5.0 engine uses a new PCM with more complex software. The added complexity is required to properly characterize all the engine functions with the new Twin Independent Variable Cam Timing," Erin explained. "The tuning task becomes much more time intensive, as there are many different 'operating points' that need to be mapped and checked. High compression paired with a supercharger also presents unique challenges when mapping borderline spark and maintaining exhaust temperatures for catalyst protection."
"In the past, high compression did not go well with forced induction. It was unknown how the cars would respond to supercharging. Now that we've done it, we know it works great.
"Ford did its homework on chamber design, swirl, burn rates, and so on," Justin added. "The 5.0 can run on 87 octane from the factory and deals with boost well on 93 octane. It's surprising how much timing you can run on a blown 5.0 with premium gas in the tank. The out-of-the-box high compression means these cars need little boost to see huge power gains, this is good for overall efficiency."
Yet another curveball with the latest Mustangs is an all-new six-speed automatic transmission that takes its marching orders from Copperhead. Of course, not all new 5.0s are automatics, but Rebecca's is, so Justin also had to get up to speed on the trans tune, too.
"With six forward gears, a good auto-trans calibration is now more important than ever," he said. "Most cars will hit four or five of these gears going down the strip; when and how hard they hit vastly effects quarter-mile times. It's worth noting that this new trans can be calibrated to shift so hard, it side-steps four feet on the 1-2 if you aren't careful ... "
As you've probably already learned by now, the combination of Justin's tuning and Roush's supercharger system bestowed some impressive performance on Rebecca's otherwise-stock '11 GT.
We plan to try a few more things on this car, but for now, keep reading to see how this kit goes on. Roush provides comprehensive instructions, but unless you are an experienced wrench-bender, we suggest you take the job to a pro.