Kicking off Lethal Performance’s 2015 Mustang GT build with the basics
By Steve Turner
After waiting patiently for its 2015 Mustang GT to arrive at Weikert Ford in Lake Wales, Florida, Lethal Performance was eager to get on with the mods. If you know anything about the company, you know it is not shy about tearing apart newborn Mustangs in the name of performance.
Seeing the Lethal Performance 2015 Mustang GT strapped down to the Dynojet at Power by the Hour in Boynton Beach, Florida, is likely to become a familiar sight. All stock, save for Lethal’s sound-enhancing resonator delete, the GT put down a baseline of 382.26 horsepower and 358.81 lb-ft of torque.
Of course, even though they plan to get far more aggressive with the build-up of this 5.0-liter-powered S550, Team Lethal knows that all of its customers won’t be twisting the power knob to the insane setting right off the bat. As such, starting with the basic bolt-ons is always part of the plan with a Lethal project.
With that in mind we made the trip down to Power by the Hour in Boynton Beach, Florida, to document the start of this project. At least the start of the project from a performance standpoint, as you can see the company didn’t wait long modding the black GT with a striking matte-blue wrap highlighted by its signature skull and crossbones logo.
We arrived in time to document several steps in the process, but we are going to start where most people with new Mustangs begin. That step is adding a cold-air intake and a more aggressive calibration. In the case of the Lethal car, the company added one of JLT Performance’s tried-and-true CAIs, which had been paint-matched to the car’s wrap.
Power by the Hour’s Jake Long gets down to business by removing the factory airbox and inlet tube as one assembly.
“We chose the JLT intake and custom tune as a starting place as that’s what most Mustang owners do to their cars shortly after purchasing them. These mods are cost-effective and provide a nice increase in horsepower and torque,†Jared Rosen of Lethal Performance said. “We know from all of our previous builds that the JLT intake not only looks the best but also performs better than the rest of the intakes on the market, which is exactly why we chose the JLT for our 2015 project car. That and the fact they’re made in the U.S. makes the JLT an easy decision.â€
As with most CAIs on new Mustangs, the JLT requires recalibrating the PCM with a new mass-air transfer function to make the factory mass-air sensor measure the proper airflow moving through the larger-diameter mass-air housing. Of course, while you are in there, you might as well tweak the tune for maximum power, and that’s just what Lund Racing’s Ken Bjonnes did. You can see the dyno runs right here:
With the induction out of the way, it was a good time to install a Reische Performance 170-degree thermostat (RP-FORD-50; $65). This is a simple remove and replace operation. You’ll just want to be sure to capture the lost coolant in a drain pain and refill the system after you install the new thermostat.With the cooler thermostat in place, Jake returned his focus to the new induction system by installing the new JLT air box using the factory fasteners and mounts.
“We’re ecstatic with the results we got from the intake and tune. The JLT intake combined with a Lund Racing custom- tuned SCT X4 makes a hell of a combo. You can definitely feel the difference,†Jared added. “These new 2015s make some awesome power with just an intake and tune. On the ’11-’14s it would take the intake and tune plus an off-road pipe to make the same power. Just wait until we slap an exhaust on this car…â€
So the Lethal S550 is off to a great start, but this build is just getting under way. In the near future, we’ll bring you the results of adding a Nitrous Express kit to the latest Coyote ’Stang, and then we’ll catch up with some other bolt-ons before things escalate with a full exhaust and a Whipple supercharger. This should be fun, so stay tuned to SVTP.
The JLT airbox mates with the stock fresh-air scoop behind the grille, and Jake slides the tube into the scoop.The JLT inlet smartly uses a coupler that reduces its larger tube down to the smaller 80mm factory throttle body. This way the system can use a larger inlet tube that will feed a larger aftermarket throttle body. Should you decide to upgrade the throttle body later, you need only change the coupler.Next Jake swaps the factory slot mass air meter into the larger JLT inlet tube.JLT offers its intakes paint-matched to factory colors, so this is obviously a custom job. However, the match is spot on and looks superb on the Lethal GT.With the new inlet tube clamped in place, it’s important to reinstall all the factory connections, including the mass-air harness and the Induction Sound Tube.After shoring up all the connections, Jake installs the JLT conical air filter.Since the theme of the day was JLT, it was an opportune time for Lethal Performance’s Jared Rosen to step in and install JLT’s oil separator. It uses factory hoses and connectors, so it’s an easy, plug-and-play operation. It will minimize oil contamination in the inlet path, which can reduce fuel octane.The paint-matched JLT is an improvement—in every way—over the stock induction system.Obviously it is necessary to recalibrate the PCM with a proper mass-air transfer function for the larger JLT inlet tube, but Lund Racing’s Ken Bjonnes also created a hotter calibration that adjusted the throttle characteristics, air/fuel ratio, timing, and more.Lethal Performance sells the JLT intake with an SCT X4 tuner and a preloaded Lund Racing tune (LP-PWR-2015GTJLTSCT-P; $853.10), so this combo mimics what you can buy.Before dyno testing the Lethal GT, Ken removed the fuse for the traction control system so the car would run on the chassis dyno without issue.After starting with the same calibration he runs on his own car, Ken tweaked it a bit for the Lethal GT to maximize this car’s combo.With the addition of the JLT Performance cold-air intake and the Lund Racing tune, the Lethal Performance Mustang GT picked up peak-to-peak gains of 26.7 horsepower and 24.93 lb-ft of torque.While the graph features the highest resolution of data points, we enjoy taking a look at the dyno data in chart form when possible. Why? Well, looking at this 100-rpm sampling more clearly illustrates just how substantial those midrange gains are. Apparently the 2015 Mustang PCM likes to manage the torque by manipulating the throttle, and reducing its interference there results in meaty gains, including a 44.27 lb-ft swell at 4,300 rpm.
Gotta love the ole self closing throttle blade. Great gains in the mid-range.