What is a Stroker Kit?

There are numerous ways to increase the power and torque of your engine. Perhaps the easiest is going with bolt-on parts like an exhaust system or an ECU tuning. You want more power? The easiest way to get more power is forced induction. Force feeding air into your engine via the use of superchargers and turbochargers is quite the norm these days. Although, the throttle might not be as snappy as before because force induction will make gobs of power at the expense of response.

And then there are stroker kits which will make a bit more power whilst retaining the instantaneous response you crave. A stroker kit is an aftermarket assembly that increases the displacement of a reciprocating engine by increasing the travel of the piston. Before turbos became popular, the route to power was always a larger displacement. This would leave lots of room within the cylinders for plenty of air and fuel to enter for combustion, creating a powerful downward stroke to rotate the crankshaft.

The stroker kit increases the displacement of the engine by lengthening the piston stroke. In order to achieve this increase in stroke, motor components modified from OEM parts will be included in the kit. They allow the piston to travel up and down the cylinder further, thanks to the use of a different crankshaft. Journals along the crankshaft lengthen the distance, depending on the severity of the stroke enlargement. The increase in the height of the journal doubles the increase in the length of the stroke. This is due to a relative increase in TDC (top dead center) and BDC (bottom dead center).

Will Installing a Stroker Kit Get Me More Power and Torque?

Now, we come to the stroker kit’s power principle. As the stroke increases, the torque output of the engine will increase due to the additional leverage created by the ‘distance’ that the force is acting from. In the same way that using a longer socket wrench to remove a wheel is easier than using a smaller stock tool, the extended stroke means a large twisting force is applied to the crankshaft.

Power is related to the torque output at a specific engine speed so an increase in horsepower will be had with an increase in stroke.

As with most of the ventures away from the OEM powertrain, there will be some drawbacks. As the piston has to travel further during its reciprocation, the amount of stress induced may increase. Horizontal load on the piston also increases during each stroke, both of which result in excessive wear. The ability of the engine to rev will also be hindered due to the increased movement of the piston. This means that the stroker kit can reduce the engine's responsiveness, potentially stripping it of its character. The new crankshaft will also need to be fully balanced for the engine at hand, with unwanted vibration becoming a matter of concern.

A stroker kit is a relatively complex modification intended only for the most practical of petrolheads. The ability to disassemble the engine, replace the key components, and then reassemble everything is not for the faintness of the heart, but the power gains associated with the stroker kit are well respected in the muscle car world. So, if you have the mechanical knowledge and hardware to do that, a stroker kit can be the key to an additional horsepower.

And, lest you forget, there is perhaps NO REPLACEMENT FOR DISPLACEMENT.

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