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A Stroker kit is an aftermarket assembly that increases the displacement of a reciprocating engine by increasing the travel of the piston (that is, the piston moves further up and/or down in the cylinder). This is done by using a different crankshaft where the crank pin is moved further away from the center of the axis of rotation of the crankshaft. While this increases displacement and torque it can potentially lower the limit to which the motor can rev safely compared to the stock configuration. == Differences from original equipment manufacturer (OEM) configurations == Two key characteristics differentiate stroker kits from OEM rotating assemblies. First, and most important, the crankshaft's rod journals are physically farther from the main journals than on the original equipment. A given extension in the distance between the rod and main journals results in twice that distance in increase of piston travel. For example, in a Chrysler LA (1971-1992) 360 cubic inch (5.9 l) V8, the rod journal centerline is 1.79 in (4.55 cm) from the main journal centerline. The piston travels 3.58 in (9.1 cm) in this configuration. When this engine is modified with a 402 cubic inch (6.6 l) stroker kit, the distance between the main journal centerline and the rod journal centerline is increased to 2.00 in (5.08 cm), which results in the piston travelling 4.00 in (10.16 cm). So, the modified crankshaft with 0.21 in (0.53 cm) further distance between the main and rod journals results in 42 cubic inches (.7 ) of displacement greater than the engine had before. The second key characteristic of a stroker kit versus OEM is the required changes to allow a stroked crank to 'fit'. This is accomplished in one of three ways: ▪ Location of the piston pin (and the top of the rod) within the piston, or the ''compression height'' is shortened. ▪ Length of the rod is shortened. ▪ Height of the cylinder is shortened. Option One - Shorter Piston: The stock Chrysler LA engine in the example above has a main to rod bearing centerline distance of 1.79 in (4.55 cm), a rod that is 6.123 in (15.55 cm) long, and a piston that is 1.67 in from piston pin centerline to top, depending on the application. As the engine stroke is increased in the example above, the 402 cubic inch (6.6 l) configuration would place the piston 0.21 in (0.53 cm) higher in the cylinder at top dead center, and with a distance of 9.585 in (24.36 cm) from crankshaft main centerline to deck, the piston would protrude about 0.21 in (0.53 cm) higher than the top deck, or would collide with the cylinder head combustion chamber. To offset this, aftermarket pistons relocate the piston pin higher within the piston itself. This change in compression height leaves the piston with 1.462 in (3.714 cm) of material in the top portion of the piston, instead of 1.672 in (4.247 cm) as is stock. Option Two - Shorter Rod: The original piston is kept and a new, shorter rod is fitted so that the original piston will not protrude above the deck. Option Three - Shorter Cylinder: As viewed from below the wrist pin this option is the same as option one - the skirt length stays the same. However, since the height of the piston is changed,the distance from the wrist pin to the top of the piston is decreased. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stroker kit」の詳細全文を読む スポンサード リンク
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