Full Bore

See how Ford lines the Shelby GT350 5.2-liter engine’s cylinder bores

By Steve Turner
Photos by Steve Turner and Tob

We know that the Flat-Plane Crank 5.2-liter engine in the Shelby GT350 needed a slightly larger bore to unshroud the valves in its high-flow cylinder heads. To achieve that extra diameter Ford uses a Plasma Transferred Wire Arc process to line the cylinder bores. This process melts steel wire and sprays atomized droplets onto the specially prepared bore. It allows an overbore without the additional weight of a traditional sleeve. In a new video, Ford is giving us a look at that process.

“The beating heart of the Shelby GT350R Mustang – the most track capable Mustang ever offered—is a uniquely engineered 5.2-liter flat-plane crankshaft V8. The crankshaft configuration and associated firing order allow for exceptional breathing enhanced by enlarged intake and exhaust valves,” says the video description. “The technology which delivered enough clearance to allow Ford engineering to include enormous 38.3 mm intake valves and 32.5 mm exhaust valves is the revolutionary Plasma Transferred Wire Arc process”

Check out the process in action right here…

“The Shelby GT350 program began with a clear objective—create the most balanced, nimble and exhilarating production Mustang yet,” Jamal Hameedi, Ford Performance chief engineer, said. “Every change we made to this car was driven by the functional requirements of a powerful, responsive powerplant. The high-revving, naturally aspirated 5.2-liter flat-plane V8 delivers on every target we set—high horsepower, broad torque curve, aggressive throttle response and light weight.”

Having driven the car, we can assure you those objectives paid off, and the PTWA process is just one of the technologies that helped the GT350 achieve those goals.

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