Toyota designs and use an internal wastegate design. Depending on where the engine was intended to be sold the exhaust turbine is either ceramic (Japan) or steel (US and Australia). It was fitted to the MR2 (North America and Japan only. There is no official MR2 for the European market with this engine.), Toyota Celica GT-Four, and the Caldina GT-T and GT-Four. Its cylinders are numbered 1-2-3-4, cylinder number 1 is beside the timing belt. The Dual Over Head Cam (DOHC) 16-valve cylinder head designed by Yamaha is made of aluminum alloy. The pent-roof combustion chambers are complemented by a cross flow intake and exhaust layout. Spark plugs are located in the middle of the combustion chambers. A distributor based system is used to fire the cylinders in a 1-3-4-2 order. The crankshaft, located within the crankcase, rotates on five aluminum alloy bearings and is balanced by eight weights. Oil holes are located in the middle of the crankshaft to provide oil to the connecting rods, bearing, pistons and various other components. A single timing belt drives the intake and exhaust camshaft along with the oil and water pumps. The cam journal is supported on 5 points between the valve lifters of each cylinder and on the front of the cylinder head. The cam journals are lubricated by oiler port located in the middle of the camshaft. To adjust the valve clearance in the first two generations, a shim over bucket system is employed. In the following generations a shim under bucket system is used. The pistons are made from an aluminum alloy designed to withstand high temperatures. An indentation is incorporated into the pistons to prevent the pistons from hitting the valves if the timing belt breaks. Piston pins holding the pistons in place are locked by snap rings. The first compression ring and the oil ring is made of steel, the second compression ring is made of cast iron. Compression ring 1 and 2, prevents gas leakages from the combustion chamber while the oil ring works to clear oil off the cylinder walls, preventing any excessive oil from entering the combustion chamber. First Generation The first-generation Toyota CT26 utilized a single entry turbine housing and a single wastegate port design. It was fitted to the first generation Toyota Celica GT-Four (ST165). The intake charge was cooled by a water-to-air intercooler and the intake manifold design is Toyota's T-VIS.