Stroker physics - where the differences are?

In a stroker engine, the stroke of the crankshaft is increased while the length of the connecting rod stays the same. Because of this, the connecting rod makes a greater angle with the cylinder bore axis at every point except TDC and BDC. This, in turn, moves the piston away from BDC and TDC more quickly.

Strokers can run more duration without having poor low-speed characteristics because the piston moves farther down the cylinder bore during each stroke. This creates a stronger and longer-lasting "suction" effect which increases the speed (and thus the inertia) of the gases flowing into and out of the cylinders. In shorter-stroke engines with long-duration/high-overlap cams, the gases don't have enough inertia at low engine speeds to properly empty and fill the cylinders between the exhaust and intake cycles. This "dilutes" the incoming air/fuel mixture at low engine speeds with already-burnt exhaust gases to the point where the mixture can't burn properly, causing misfiring at low speeds and the choppy/lopey sound that comes with a radical cam.

Stroker engines require less total ignition advance again because of the increased piston speed towards and away from TDC and BDC. This produces less "dwell" time where there is little/no movement of the piston at the top of its stroke and gives the air/fuel mixture less time to burn, which reduces the amount of ignition advance that needs to be run for optimal combustion efficiency.