ProCharged S550 Mustang Poised To Break Into The Sevens

Have you ever second-guessed buying a car because you knew you couldn’t resist the constant need to modify it? Probably not, but project cars have a funny way of beginning with modest intentions and spiraling into mega-powered machines. If there was ever a classic example, it is Walter Stietzel’s ProCharger-equipped 2016 Mustang GT, which recently made its quickest drag strip pass thus far — an 8.07 seconds at 172.34 mph.

Making a 7-second ‘street’ car is never easy regardless of what you bring to the table… — Ken Bjonnes, Palm Beach Dyno

That’s an impressive number for any performance vehicle, but considering this stallion is still street-capable with a single centrifugal blower boosting its fortified Coyote engine, it is downright stunning that it is running into the single digits where only dedicated race cars once dared to tread.

Currently powered by a BES Coyote engine fortified with a full array of upgrades (see mods sidebar) and boosted by a ProCharger F-1A-94, Walter’s 2016 Mustang GT pumped out more than 1,272 horsepower and 876 lb-ft of torque at the wheels through the old 6R80 transmission. He hasn’t been back to the dyno with the new, more efficient air-to-water intercooler TH400 automatic arrangement, but the car runs 10 mph faster, so he is confident it currently exceeds 1,300 horsepower, which is enough to propel this S550 to the precipice of 7-second elapsed times. (Photos courtesy of Walter Stietzel)

“This car was my daily driver, and the goal was for it to be a 10-second daily,” Walter told us. “As modifications progressed, the car performed exceptionally well with each phase, making the next level come much quicker than anticipated.”

Having previously owned a turbocharged SN-95, he bought this car with a ProCharger P-1SC underhood and was excited to put his foot to the floor with the new combo, as he believes the company’s Stage 2 kit is an “awesome setup” for the 2015-and-newer Mustangs.

In that configuration, it ran 11.30 at 127 mph, but after a call to Ken Bjonnes at Palm Beach Dyno, it didn’t take long for the car to drop into the high 10s. Ultimately, it ran a 9.80 at 141 with P-1SC, 93-octane fuel in the tank, and a Circle D torque converter in the 6R80 six-speed automatic transmission.

“Having a properly built car is the key component beyond the main power adder. So many customers fail to realize this, but Walter is extremely detail-oriented and makes my job as easy as possible,” Ken explained. “ProCharger has always been a leader in making horsepower, so the key is the entire recipe.”

However, at this point, it transitioned from daily driver to weekend toy and picked up an upgraded fuel system to support E85 fuel and more boost. At that time, Walter — who does most of the wrench-bending outside of the machine work and transmission building — was certain it was the quickest S550 boosted by the ProCharger P-1SC street supercharger as it laid down an impressive 9.01 at 150 mph run.

Other than the racy shifter that actuates the TH400 automatic in the tunnel, the interior of this S550 still appears as the crew at Flat Rock intended when it rolled off the assembly line. It even retains ice-cold air conditioning!

“Then I decided, let’s go eights. I commissioned Bischoff Engine Service in Indiana to build a sleeved engine,” Walter said. “Then I reached out to ProCharger to have the P-1SC upgraded to a D-1X and tested their new-at-the-time crank support. With the 6R80 still in place with Circle D Converter, the car went 8.43 at 159 mph.”

Though he believed the D-1X had more in it, Walter stepped up to the F-1A-94, which yielded an 8.35 at 165 mph despite some transmission troubles. He eventually opted for a TH400 automatic swap and an air-to-water intercooler to quell the temps generated by 28 pounds of boost.

Corralling a combination like this could be daunting without a support system in place. For that, Walter relies on the likes of RoadCone Racing, BA Motorsport, Cortex Racing, Rogue RaceCars, Extreme Automatics, Beefcake Racing, and Palm Beach Dyno, the latter of which is key to the on-track success.

ProCharged S550 intercooler tank

In the spare tire well, a PNR intercooler tank works with a CWA400 pump to transfer heat from the air-to-water intercooler to the heat exchanger that tames the inlet temps generated by 28 pounds of boost.

“Palm Beach Dyno provides an incredible service with their trackside support. This effort by PBD is why the car performs the way it does. They are quick to respond and easy to communicate with,” Walter said. “As part of the support offering, you get access to the trackside support calendar. Analysis of each pass ensures the tune is on point. That affords me the time to focus on suspension tuning and driving.”

“In a case like this, it is critical. Walter did struggle when swapping to the TH400 due to converter setup, but we were able to identify that quickly by analyzing the data and realizing we were doing everything in the tune we could but couldn’t get the first 100 feet figured out,” Ken added. “This also carried over into making a gearing change in the trans, and it finally all came together.”

With help from PBD and an optimized torque converter from Pete Nichols at Circle D Specialties, Walter ran his latest personal best, which gives him the confidence to reach his 7-second goal, so stay tuned.

Walter Stietzel 2016 Mustang GT Mods

  • Sleeved 5.2-liter Predator block
  • Boss 302 crank crankshaft
  • Manley pistons
  • Molnar connecting rods
  • BES-prepped Gen 2 heads
  • Ferrea valves
  • PAC valve springs
  • COMP Cams, blower cams
  • GT350 phasers and timing chains
  • Custom intake manifold by RRC
  • ID1700x fuel injectors
  • Three Fore Innovations 285-lph fuel pumps
  • 2-inch ARH headers
  • 3-inch MBRP race exhaust
  • Stage 2 ProCharger F1A-94 supercharger with eight-rib belt
  • ProCharger crank support
  • Custom air-to-water intercooler
  • PNR intercooler tank w/ CWA400 pump
  • Turbosmart Raceport BOV
  • Extreme Automatics Stage 3 TH400
  • Reid bellhousing
  • Custom converter from Circle D Specialties
  • M&M shifter with C02
  • JPC SFI flexplate
  • JPC crossmember
  • Derale cooler
  • JPC-spec carbon driveshaft
  • DSS axles
  • Outlaw Motorsports-built IRS with 3.73 gears
  • Cortex toe links
  • Cortex control arm bushings
  • Custom rate rear springs
  • Viking Crusaders struts and shocks
  • Steeda shock mounts
  • Steeda adjustable caster/camber links
  • Steeda vertical links
  • Weld V-series front wheels, 17×4.5 inches
  • MT ET Street front tires, 27×6.5-17
  • Weld S76 beadlock rear wheels, 17×10 inches
  • MT ET Street R rear tires, 305/45-17
“Based on this last outing, I’d say it’s a given at this point, but there was certainly a time that we were struggling. I think that is the key takeaway,” Ken said. “I’ve known Walter almost 20 years now, and I’ve been doing this 20 years, yet it still took a lot of work from both of us to get here. Making a 7-second street car is never easy regardless of what you bring to the table.”

“The car running 8.07 in terrible air was an indication that sevens will come with good air,” Walter added. “We were also very conservative on the launch and shift points. It is running sevens next time out, for sure!”

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Steve Turner

Steve Turner brings decades of passion and knowledge in the world of Ford performance, having covered it for over 20 years. From the swan song of the Fox Mustang to the birth of the Coyote, Steve had a front-row seat.
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