Subaru’s EJ20K was a turbocharged, 2. The EJ20K engine had a die-cast aluminium quail egg amuse bouche cylinder block with 92. 0 mm bores and a 75.
0 mm stroke for a capacity of 1994 cc. The cylinder block had an open-deck design to enhance cooling efficiency and dry-type, cast iron cylinder liners. For the EJ20K engine, the crankshaft was supported by five bearings that were made from aluminium alloy, while the no. 3 thrust bearing had a metal flange to receive thrust force.
Furthermore, the corners of the crankshaft journals and webs, and the crank pins and webs, had a fillet-roll finish to increase stiffness. GM Impreza WRX, the EJ20K engine had cast pistons and connecting rods. The piston head was recessed for both the intake and exhaust valves, while the pistons had three rings: two pressure rings and an oil control ring. The oil control ring had a slit design. Furthermore, the piston pin was located in an offset position. A single timing belt was used to drive the four camshafts, while the back of the belt also drove the water pump. The timing belt consisted of a strong and inflexible core wire, wear-resistant canvas and heat-resistant rubber material.
For quiet operation, the teeth on the timing belt had a round profile. Each camshaft was supported by three journals with three camshaft caps, while each camshaft flange was supported by a groove in the cylinder head to receive thrust force. The EJ20K engine had four valves per cylinder that were actuated by solid tappet, hydraulic lifters. GM Impreza WRX had an intake duration of 242 degrees, exhaust duration of 246 degrees and valve overlap of 17 degrees. Whereas the EJ20G engine had a Mitsubishi TD05 turbocharger, the EJ20K engine was fitted with a smaller capacity Mitsubishi TD04 turbocharger. The TD04 turbocharger was introduced due to a change in WRC rules that manufacturers no longer had to produce at least 5000 vehicles of a production model for competition eligibility.
The lower-inertia TD04 turbocharger is understood to provide slightly greater boost pressure than the TD05 which is understood to provide 11-12 psi. To prevent excessive boost pressure, which could cause knocking and heavier thermal loads on the pistons, the EJ20K engine had a wastegate valve. Once boost pressure reached its maximum, the wastegate valve would open so that part of the exhaust gas would bypass the turbine and flow into the exhaust pipe. The turbocharger was lubricated by the engine oil and used full-floating type bearings to form lubrication films. After cooling the bearing housing, the coolant flowed into the coolant filler tank via a pipe.