Michael Johnson
Technical Editor
December 27, 2016

Remember when making 500 horsepower was a big deal? Then the number to beat became 700 horsepower. Nowadays, 1,000 horsepower Mustangs are commonplace, and we’re now even pushing toward the 1,500 horsepower plateau. Technology, power adders, advanced tuning practices, and more efficient engines have been the driving force behind escalated horsepower figures, and there’s no sign of slowing down.

Jim Braun’s 2012 Mustang GT recently made an astronomical 1,396 horsepower at the wheels on 29 pounds of boost. How did he do it? You’re about to find out. First things first, the engine was sent to Fast Forward Racing Engines (FFRE) for machining. Once sleeves were added, Jim added a Boss 302 crank, Callies billet connecting rods, Diamond custom pistons, Clevite bearings, ARP hardware, and MMR oil pump gears. Using Cometic head gaskets, Jim then bolted on a pair of Boss 302 heads with PAC valve springs, Manley valves, Boss 302 exhaust cams, and stock intake cams. To make sure the engine is in perfect time, Jim added a MPR timing chain gear set, while an ATI balancer and a Circle D flexplate makes sure the engine doesn’t shake itself apart. Up top, the now-venerable Boss intake takes incoming air, mixing it with ID1700 injectors.

Feeding fuel to the home-built, twin-turbocharged Coyote/Boss combination is an On3 triple fuel hat featuring Walbro 460 pumps, an Aeromotive fuel pressure regulator, and ID1700 injectors. Making the combination capable of making 1,396 horsepower at the feet is the tuning exploits of Sai Li via SCT software.

For power, Jim fabricated the car’s turbo system using a pair of Precision 6266 turbochargers, Tial wastegates and blow-off valve, custom air-to-air intercooler, 1 ¾-inch turbo headers, 3-inch stainless downpipes, Vibrant Vanjen clamps, and a Boost Leash boost controller. Further down the exhaust tract is an MBRP 3-inch after-cat exhaust. Originally an MT82 car, Jim swapped the stick for a Brett LaSala-built 6R80 automatic with Exedy clutches, a TCS billet intermediate shaft, a Circle D converter, a Shaftmasters driveshaft, and a BMR driveshaft safety loop. To ready the stock rear for the onslaught of horsepower, Jim welded the axle tubes, and added a TrueTrac differential with a Moser differential girdle.

“Interior is stock,” Jim says with a laugh. That is temporary, however. Jim plans to add a cage in January before the new race season; although, Jim lives in Clearwater, Florida, where racing season never ends.

For suspension, Jim mixes BMR components with Viking double-adjustable rear shocks and Strange Engineering single-adjustable struts up front. At the track, Jim uses Race Star wheels with 15x10 examples out back with Mickey Thompson ET Street Radial Pro 275 radials. Jim recently attempted a few track passes, but bringing in the power resulted in finding a weak link in the transmission, which is in Brett LaSala’s hands repairing said weak link.

“All of the welding, fabrication, assembly, and mechanic work of this car was done out of my garage. Engine was machined by FFRE and assembled by me. Without the help of great friends like Sai Li, Brett LaSala, and my wife this would not be possible,” Jim says.