Electric V8 Engine (Cylinder Based Speed Control)

This Engine is for a Boat i am designing. I got the idea for the engine from youtube and actually designed a 12 cylinder micro version first.

this engine uses size 130 DC motors with optical AB Phase Encoders mounted to the back of them (see: https://www.ebay.com/itm/130-Motor-DC6V-12V-7800RPM-Metal-Speed-Encoder-Tachometer-Motor-AB-Phase/192486576192?epid=18003843567&hash=item2cd1181040:g:hKUAAOSw5k1cdyBy )

gears and shafts are all 0.8 modulus plastic gears that come in assortments on e