If there's one thing we've learned over our years of testing speed parts, it's that positive-displacement superchargers hate inlet restriction.
We'd have to say that JLT...
We'd have to say that JLT Performance was spot-on in naming its 127 cold-air intake Big Air. Its inlet is simply huge. It's about as tall as a soda can, and its one-piece design offers a smooth, straight air path. For carbon-fiber fans, the Big Air offers a beautiful, clean visage. JLT will eventually offer the Big Air in a more affordable plastic version, which can be painted to match your ride.
Over the course of its development, Project Vapor Trail has worn a number of different inlet combinations as it climbed the ladder to higher and higher boost levels. It was practically born with the standard 113mm FRPP kit (PN M-9603-M54SC; $350) and TVS, and from there it moved up to a Ford GT inlet tube and 123mm Cobra Jet (PN M-9600-CJ; $665.95) mass air housing. This gradual increase in inlet tube and mass-air-housing diameter helped maximize the growing boost built with the additions of an FRPP/Innovators West overdrive balancer, and VMP Tuning's inlet elbow and dual 72mm throttle body. With these free-flowing parts maximizing the FRPP TVS, PVT was building over 18 pounds of boost and surpassed 700 rwhp in ideal conditions.
"The 123mm and 127mm are significantly larger in size than the 113mm. The 113mm is capable of metering enough air for a car making well into the 600s at the tire," Justin Starkey of VMP Tuning explained. "Over 700 rwhp though, and you need a larger housing to reduce restriction and increase mass air sensor range. With the larger housings, the factory mass air sensor is capable of measuring over 100 lb/min of air. That puts you into the 800-plus-rwhp area."
Naturally we had to reset...
Naturally we had to reset our baseline for the current combination. Our previous-best numbers were set back in January 2010, and the air was considerably cooler (at around 65 degrees in the dyno room) and denser. Back then it smacked the rollers with 706 hp and 700 lb-ft at the rollers. Still, our baseline numbers were pretty stout at 88 degrees, with PVT laying down 687/673 at the feet while drawing through the 123mm housing and GT tube.
Obviously the combo was working, but there was just one problem. The GT tube is obviously free flowing, but it's not exactly a clean, direct fit on a GT500; perhaps more importantly for me, it's not carbon fiber. As such, when our friends at JLT Performance released a one-piece, all-carbon 127mm CAI (PN CFCAI127-GT500-07; $449), it was a must-have addition for PVT. Not only is it larger, but it offers a much cleaner presentation.
Of course, we couldn't just throw it on and drive away. It would require a bit of tuning, so we headed over the VMP Tuning to have the combo refined with SCT software and test it against PVT's prior configurations.
On the Dyno
"When tuning for larger intakes, start with your stock mass air transfer function, or whatever you had before that is known to be accurate, and do the math. If your new mass air housing has roughly 20 percent more area, then you use that as the starting point for your tune by multiplying the current transfer function by 1.2," Justin said of the tuning process. "From there, you fine-tune the transfer function based on feedback from a wideband O2 sensor."
As you can see, the 123mm only bested the 113mm by 1.08 hp and 6.63 lb-ft at the peaks on the graph, but looking at the charted data you can see it's far better from 2,000 rpm through 5,000 rpm, but the 113mm managed to hang in there from 5,500 to 6,000 rpm. Obviously the graph has more data points, but the chart allows a snapshot of what's going on across the curve.
Adding the JLT Big Air 127mm raised the peak numbers by 6.17 hp and 4.39 lb-ft. You can see that moving the inlet progressively larger added boost to the equation, but interestingly, moving to the 127mm was like moving to a short-runner intake manifold. It gave up a little down low but thundered from 5,000 rpm up. Of course, if you compare the 127 to the more attainable 113mm, the Big Air is better across the board.
It's worth noting that the temp in the dyno room crept up from 88 to 92 degrees during our testing. We'll have to revisit this combo in the winter and see how the glory numbers stack up with the new combination.
For a little back-to-the-future...
For a little back-to-the-future fun, we decided to go back to PVT’s original 113mm CAI configuration to see how it performed against the larger inlets. It performed surprisingly well. While this system gave up some power and torque across the lower end of the range, it actually performed near or better than the 123 and GT tube above 4,500 rpm. That was a bit of a surprise.
As is common practice with...
As is common practice with modern Mustang cold-air intakes, swapping the slot mass air electronics is a simple two-fastener job. According to JLT, a move to high-quality, pre-preg carbon-fiber made the one-piece design possible. The autoclave process ensures consistent parts, which makes dialing in the Big Air a known quantity for tuners.
JLT include its own sealed...
JLT include its own sealed airbox with the Big Air kit, as it must not only accommodate the larger tube, but the 5x9-inch S&B air filter. The box features a rubber seal at the hood to block off hot underhood air. There is another version for the ’10-’12 GT500s which incorporates the factory ram-air tubing.