Increased Engine Capacity
Here at AMAC Engineering we re-bore engine blocks to specific sizes to accommodate oversized pistons. Generally when the capacity of an engine is increased, so too is the power and torque output. Most standard sized engines can be re-bored larger and have larger pistons fitted.
With the extra bore capacity, there comes a need for extra fuel to fill the cylinder. When the bore is increased and the stroke distance remains standard there is a need for greater accuracy of camshaft because of the effectively smaller window for the FAM to enter the combustion chamber. This is especially true, as other engine modifications will make the engine rev higher.
Strictly speaking it is best when increasing the bore size to also proportionally increase the stroke length of the piston. However this is an expensive process as it requires a new crank, piston rods, and an extension plate on the block, with internal liners. Therefore it is generally only the bore diameter that is increased.
Whenever an engine capacity is increased it is necessary to increase the engines breathing ability. This is achieved by fitting larger valves to supply the extra FAM needed to fill the extra capacity of the resized bores. Because the valves have been resized to get the greatest power output the cylinder head will need modifying.