Titan Motorsports - 2JZ BILLET MAIN CAPS FOR THE SUPRA MK4The Titan Motorsports billet main caps are precision machined from high tensile billet steel. We developed these main caps out of necessity for our 2JZ race program and soon found them to be applicable in most street engines. With the increased boost levels seen in single and larger twin turbo setups, the factory crank pushes down on the caps often leading to stress fractures and cracks. The factory main caps were not designed for the forces required