Born to Run
Adding a Boss intake to a 2015 GT lets it rev to the moon
By Steve Turner
Photos courtesy of Ken Bjonnes/Lund Racing
We have seen a furious development cycle for 2015 Mustang products. From 949-horsepower turbos to simple hood-lifts, the new Mustang has inspired the aftermarket just like we expected it to. However, beyond the basics of cold-air induction, we have yet to see much effort in opening up the intake of the new GT.
Students of the sport know that the latest version of the Coyote 5.0-liter engine took advantage of many of the lessons learned from development of the high-revving RoadRunner engine that propelled the corner-carving 2012-2013 Boss 302s. However, unlike that engine, the current V-8 had to fit under the swoopy bodywork of the new Mustang, so a taller intake like the Boss manifold was out of the question.
Moreover, the latest intake manifold incorporates Charge Motion Control Valves just before the junction of the intake and cylinder heads. These valves—which were formerly called Intake Manifold Runner Controls when the last appeared on the Mustang Cobra—are closed at low rpm to promote torque production. As the tach climbs, they move out of the way to let the air flow for enhanced power.
While it might be too tall, the Boss 302 intake is still a bolt-on proposition for the engine. As such, when we learned that Lund Racing’s Ken Bjonnes was trying a Boss 302 intake on his personal Mustang GT at Power by the Hour, we were excited to see the results. Ken added the intake to his GT, which had thus far been upgraded with a JLT Performance cold-air intake, American Racing Headers long-tube headers, and an American Racing Headers X-pipe.
“It bolted right on as expected, but as you know, it doesn’t fit under the stock hood,” Ken explained. “Options may be to lower the engine or install a new hood, but the intake isn’t staying on my car for now.”
Getting the taller intake to fit under the hood is only one of the pitfalls. The Boss runners are nearly 2 inches shorter than the stock intake runners, so it can sacrifice some torque. It also lacks those Charge Motion Control Valves in the runners, which the factory PCM expects to be there. Fortunately tuning is Ken’s specialty so he was well equipped to make the car play well with the new intake.
“The biggest challenge is deleting the new IMRCs for the 2015. In years past when they were used, it was a much simpler implementation,” Ken said. “With TiVCT in play, things get much more complicated in general and that carries over to the IMRCs.”
Because he wanted to perform a back-to-back test, Ken only tweaked the existing calibration in his car, via HP Tuners hardware, to get the computer to accept the missing Charge Motion Control Valves. He did not work on maximizing the combo’s performance.
“The main reason I did the test was to discover the higher rpm results. I don’t like how the stock 2015 intake really noses over above 6,500. After doing the headers on my car, I knew it wasn’t the exhaust,” Ken said. “So since I had the Boss intake lying around, I decided to give it a shot. And, it pretty much did as I expected. It lost a little down low and picked up tons of power up top. What I didn’t expect was for it to pull all the way to 8,000. I definitely want to see what a set of cams will do in this setup.”
Watch Ken’s S550 rev to 8,000 rpm on the Dynojet at Power by the Hour in Boynton Beach, Florida, right here…
As you can see from the dyno results, the new-school Coyote definitely howls at high rpm with a Boss 302 intake manifold. It does give up some low-rpm performance, which you might notice on the street, but at the track that high-revving power is enticing. It will be interesting to see what this intake will do with other mods and more tuning, but the early returns are certainly promising.