Modern performance vehicles truly are marvels of engineering. An immense effort is put forth designing these cars so they produce impressive performance while meeting emissions, fuel mileage and noise standards. No area of the car is immune from these limitations, including the induction system. Checking off all those boxes means making a few compromises, but that’s where the aftermarket comes to the rescue.
To see how the JLT installs and performs on the latest Mustangs, we turned to Coastal Chassis Dyno and a customer’s new 2017 Mustang GT. Stock save for a few suspension bolt-ons, this car put down some solid numbers on a moderate fall day in Tampa, Florida.
In the case of the induction system, one of the most popular cold-air induction systems produced for late-model Mustang is from JLT Performance. The company got the jump on designing a kit for the Coyote engine in the 2015+ Mustangs, and they haven’t looked back except to tweak the system with some minor upgrades.
Coastal’s master tech Steven Harris gets down to business by disconnecting the factory Induction Sound Tube (IST), which pipes inlet sounds into the cabin. The factory system must meet a number of standards, including how loud it is, so the IST is a way to connect the driver with the engine sounds. The JLT system is compatible with the IST, but it also supports deleting it with plugs as well.
As you know, aftermarket cold-air induction systems replace the factory sealed air box, its internal panel air filter and the ribbed hose that connects the box to the factory throttle body. In place of this system, JLT Performance adds its larger-diameter tube capped by a free-flowing conical filter that fits inside an air box, that seals that box to the hood and joins with the factory fresh air duct via scoop behind the front grille.
You might assume that the system from the 2011-2014 Mustangs might carry over to the latest pony car. However, there were significant chassis upgrades and a revised induction system designed to fit under the lower hood that required JLT to create a unique system for the 2015+ Mustang GTs (the company also offers systems for EcoBoost and V6 S550s).
Steven removes then loosens the inlet tube clamps and unbolts the airbox so that he can remove the factory induction system in one piece.
One thing that we wanted to do differently on the ’15 than we did on the previous models was allowing the throttle body end to be larger for future larger throttle bodies.—Jay Tucker, JLT Performance
“We know the sizing. We know that with the previous 2011-2014 5.0-liter at 107mm we could make good power. We actually tried to up it a little more with the ’15 and it worked…” Jay Tucker, of JLT Performance, explained. “One thing that we wanted to do differently on the ’15 than we did on the previous models was allowing the throttle body end to be larger for future larger throttle bodies.”
“We use a reducer to go from the tube to the factory throttle body that actually creates a Venturi-effect, which is more ideal than a tube that meets the throttle body perfectly,” Jay added.
Freed from the limitations of the factory engineers, JLT can focus on simply improving performance. The open-element air filter also contributes to a more performance-oriented personality from the engine courtesy of more induction noise.
Improving the Flow
With the factory system removed, the path is clear to install the JLT cold air intake. This system is built for the factory 80mm throttle body, but it can accept a larger unit by way of new silicone coupler.
“The open-element filter is really what is going to create the power. Going from a closed filter to an open-element filter—even though we are sealed to the hood—we’ve got more surface area in all the pleats of the filter; and that’s what is going to allow more air to come in. The pleat depth and the type of filter is what really help that thing flow. With the stock box on the new body style, we all know that the factory filter had to be reduced to about half the size of the previous car to make it fit.”
As we mentioned, JLT was the first to produce and sell a cold-air induction system for the latest Mustang GT. Though the system was a hit right out of the gate, Jay and his team have continued to tweak its features to deliver the best possible performance, including adding a seal at the inlet tube to air box junction to further isolate the filter from the engine compartment.
After swapping over the rubber locating spacer, mounting grommet and metal insert from stock box to the JLT, Steven slips the new air box into place and joins it to the factory fresh air scoop in the grille with the included tube. Simply line up the tube and push it over the scoop by pushing down on the rear of the scoop so the tube clears the bump on the scoop.
“Sitting still for about 20 minutes in testing, we saw a 10-degree temperature difference (without the seal), so it actually was cooler under the hood,” Jay said. “And, driving around, in city traffic we noticed that it would take longer to creep up and it would cool down faster. It actually did benefit and people are buying them (as a retrofit upgrade).”
To try out the latest iteration of the JLT system, we turned to Coastal Chassis Dyno and a pristine 2017 Mustang GT owned by a regular customer. When we arrived, the car was stock save for a few suspension bolt-ons. Sam Lippencott baselined the stock configuration before Coastal’s master technician Steven Harris installed the JLT CAI.
With the new system in place, Sam dialed up a custom tune for the JLT-equipped Coyote. Because the air volume and velocity is different with the new induction, the mass air transfer function must be adjusted. Of course, if you are tuning, you might as well optimize the combination. In this case, the 2017 Mustang GT is much like its 2015-2016 predecessors, so Sam knew just what to do.
Tuning It Up
Don’t put the factory induction on the shelf just yet, however. You will need to swap over the factory slot-style mass airflow meter from the stock air box into the JLT tube. Aside from its larger, smooth inlet tube, another advantage of the JLT CAI is the high-flow S&B conical air filter included in the kit. Steven clamps it to the tube and slips on the coupler so he can install this setup in one piece. Steven lays the tube into place and slips the silicone coupler over the throttle body, leaving everything loose so he can check the fitment.
“There’s not really anything different from ’15 on up. They really haven’t changed anything,” Sam said of the calibration he created using HP Tuners software. “Basically transfer function, timing, cam timing and everything typical to a normal tune.”
Install Tools Needed
5/16 nut driver
10mm socket, ratchet, extension
T-20 Torx driver
Phillips head screwdriver or 7mm socket
By adding the JLT intake and a companion tune from Sam, the new Mustang picked up peak-to-peak gains of 15 horsepower and 24 lb-ft of torque at the rear wheels on Coastal’s in-ground Mustang Dynamometer.
“On a cold air and tune combination that’s usually what you pick up,” Sam said. “You may or may not see a bigger difference between dynos and tuners and stuff like that. Everything that I do, I do hot. I don’t do anything cool, so it’s easy to pick up another 10 or 15 if you let the car cool off.”
Next, Steven tightens the silicone coupler on the throttle body and bolts down the JLT air box. Here’s a look at the finished installation. The JLT definitely looks like it flows more air and that foam seal helps further isolate the air filter from underhood heat. JLT recommends that you inspect the filter at every oil change interval and clean it as necessary.
We certainly left impressed by a brand-new Mustang putting down over 400 horsepower at the wheels with only one mod and a matching calibration. More impressive yet were the gains under the curve.
“We typically see 30 horsepower,” Jay said. “I have seen 30-plus eight or nine times. That car started out strong, so it only picked up 15 peak, but it picked up a ton throughout…”
Sam Lippencott of Coastal Chassis Dyno used HP Tuners hardware and software to dial in a standard calibration for a stock Coyote with a cold air intake. Most importantly, he recalibrated the mass air transfer function to ensure the PCM is measuring the proper amount of air. He also tweaked the ignition timing, cam timing and other parameters to maximize performance. Stock (left) the 2017 Mustang put down 387 horsepower and 360 lb-ft of torque. The addition of the JLT cold air intake and a custom tune from Sam Lippencott at Coastal Chassis Dyno resulted in peak-to-peak gains of 15 horsepower and 24 lb-ft of torque. The newly upgraded S550 topped out at 402 horsepower and 384 lb-ft of torque (right). However, it is those under the curve gains that really impressed. The car pulled harder throughout the run, but from 4,000 to 6,000 it was much stronger.