Abstract: A crankshaft of an in-line, four-cylinder internal combustion engine has five journal portions. The journal portions are each supported by a main bearing unit. Each of the main bearing units includes a cylinder block side bearing part and a bearing cap. The No. 1, No. 2, No. 4 and No. 5 main bearing units employ an iron-based bearing cap, and the No. 3 main bearing unit at the center employs a bearing cap made of an aluminum alloy having a relatively high thermal expansion coefficient. At high temperatures, the bearing clearance of the No. 3 main bearing unit is configured to expand so as to reduce bearing load.

Abstract: A method to modify the geometry of a connecting rod of an internal combustion engine includes providing a connecting rod having a crankshaft bore at a first end, wherein the first end has a bearing cap and a bottom end portion of the connecting rod, mating the bearing cap with the bottom end portion of the connecting rod to form the crankshaft bore of the connecting rod, machining a width upset portion of the bottom end portion to reduce a width of the bottom end portion of the connecting rod, machining a width upset portion of the bearing cap to reduce a portion of a width of the bearing cap, and reducing the width of the bottom end portion of the connecting rod and the portion of the width of the bearing cap to a width smaller than a cylinder bore of the internal combustion engine.

Abstract: A crankshaft of an in-line, four-cylinder internal combustion engine has five journal portions. The journal portions are each supported by a main bearing unit. Each of the main bearing units includes a cylinder block side bearing part and a bearing cap. The No. 1, No. 2, No. 4 and No. 5 main bearing units employ an iron-based bearing cap, and the No. 3 main bearing unit at the center employs a bearing cap made of an aluminum alloy having a relatively high thermal expansion coefficient. At high temperatures, the bearing clearance of the No. 3 main bearing unit is configured to expand so as to reduce bearing load.

Abstract: A method to modify the geometry of a connecting rod of an internal combustion engine includes providing a connecting rod having a crankshaft bore at a first end, wherein the first end has a bearing cap and a bottom end portion of the connecting rod, mating the bearing cap with the bottom end portion of the connecting rod to form the crankshaft bore of the connecting rod, machining a width upset portion of the bottom end portion to reduce a width of the bottom end portion of the connecting rod, machining a width upset portion of the bearing cap to reduce a portion of a width of the bearing cap, and reducing the width of the bottom end portion of the connecting rod and the portion of the width of the bearing cap to a width smaller than a cylinder bore of the internal combustion engine.

Abstract: A method to modify the geometry of a connecting rod of an internal combustion engine includes providing a connecting rod having a crankshaft bore at a first end, wherein the first end has a bearing cap and a bottom end portion of the connecting rod, mating the bearing cap with the bottom end portion of the connecting rod to form the crankshaft bore of the connecting rod, machining a width upset portion of the bottom end portion to reduce a width of the bottom end portion of the connecting rod, machining a width upset portion of the bearing cap to reduce a portion of a width of the bearing cap, and reducing the width of the bottom end portion of the connecting rod and the portion of the width of the bearing cap to a width smaller than a cylinder bore of the internal combustion engine.