Threshie Motorsports 5.2 large bore/stroker engines are the largest available engine based on the 4.6 Cobra. These engines offer the most torque and power for street and mild race supercharged use. Great for making the most power on street fuels, and very close to the 5.4 size without the weight. The 5.2 engine uses a 3.70" bore which is the largest possible, and a 3.677" stroke. The larger bore size mandates fusion bonded cylinder liners. These custom bonded liners offer the ultimate in block strength and heat transfer, and are another exclusive feature of our engines. 5.2 engines use O-ringed blocks with copper head gaskets for optimum combustion seal. Levels III & IV cylinder heads are listed as standard.