Nitriding is a chemical hardening process in which the part is heated in a furnace, the oxygen is vacuumed out, and nitrogen is introduced which penetrates the entire surface. The depth of hardness is dependent upon the time the crankshaft is exposed to the gas. Typically, a nitrided crankshaft will have a hardness depth of about .010 - .030. Nitriding is a low heat process compared to Tuftriding, but it shares the advantage of avoiding the introduction of localized stress zones as in induction hardening.

Subaru 2.1 Stroker Kit increases the cubic capacity of the 2.0 litre engine to 2.1 litres by lengthening the stroke, that is, the amount by which the piston travels up and down in the bore. A Subaru 2.1 stroker engine has a 79mm throw crankshaft in order to do this. A Subaru 2.1 stroker kit needs special short skirt pistons so that the bottom of the piston does not travel too far below the bottom of the piston bore.

See also 2.35 Stroker Engine Pistons