When considering the Twin Cam engine, themes of lightness, strength, and efficiency run through the list of changes. The crankcases benefit from a high-pressure process and arrive on the assembly line stronger, lighter, and manufactured to tighter tolerances. The straight single crankpin sports an increased diameter for more bearing area, increased reliability, and the ability to withstand the higher output of performance-tuned (read: large displacement) engines. Forged flywheels get a tougher press fit introduction to the crank. Beefier knife-and-fork connecting rods guide lighter, wider, 95.3mm pistons through a shortened 101.6mm stroke, yielding both a 1450cc (or 88-inch, as in Twin Cam 88) displacement and a higher 5500-rpm redline. The combustibles receive their jolt from a smaller 12mm spark plug located in the new bathtub-style combustion chamber, with its higher 8.9:1 compression ratio.