Yep, stews thread was removed because it was first post advertising and goes against the T&Cs of the forums.... He has been Pm'd to help resolve the issue, we await his reply

Stroker engines have the piston throw, both up and down lengthened to increase engine displacement. Normally by crankshaft change, with associated items, pistons etc etc normally changed at the same time....

Somebody will probably give you a more in depth answer but that about sums it up