Stirlingengineforum.com

You could gain some power (torque) with additonal cylinders over a single large engine if the cylinders power stroke is staggered. (like in any multi-cyinder internal combustion engine) You will get multiple power stokes in a single crank rotation. The friction problem has more do due with your ability to manufacture an accurate crankshaft. Getting a muti-cylinder "tin can" engine all lined up would be difficult. For the basic hobbyist with just basic tools and materials, your likely to have many problems getting it to work over a simpler single cylinder design.

K.I.S.S. make it multi cylinder in radial format. Make all cylinders have a shared connection to the flywheel. solves timing and machining/fabrication nightmares. just keep it level and keep it smooth. I'm working on a five cylinder lamina based on this "single connection radial format"

This sounds interesting. You must have some good modeling skills if a radial design fits into the KISS principle for you. And I mean no disrespect. I'm certainly not there, but I would love to see your design. Best of luck,

Dale.