First of all eminent, torque is different than horsepower. You can't make torque and horsepower the samething, all though horsepower is a direction corrollation of torque produced at a given rpm. Second yes one can judge torque in relation to displacement as more volume is given to power production per stroke of the piston. In this way, for instance, a 3.0L car engine will produce less torque than a 6.0L engine. For example the OS.18 has a 15mm stroke/16mm bore and the VX .18 has a 14mm stroke/16.5mm bore. So in basic operation of engine mechanics, the OS.18 will produce more torque (longer stroke) and the VX.18 will achieve a higher rpm because it has a shorter stroke. In addition port timing for both intake and exhaust can affect engine performance for two stroke engines. Now don't get me wrong, please read my above post in which I stated I did have to replace my aluminum shoe clutch with a nylon one and hence the reason why I possibly wasn't seeing an increase in bottom end torque. Nylon does not grip as well as aluminum does. Also as you said the OS TZ produces significantly more horsepower over the OS CV-RX, even though they have the same displacement, because it has a slide carberator and rear exhaust both of which increase engine efficiency. Now I am NOT giving the OS.18 a bad rap, I am sure it produces more power over the VX...if it didn't I wouldn't have bought one. But as for a BIG difference in power production the OS.18 doesn't really have that much more over the VX.18 as say the OS TZ does. While I am at it did I say the OS.18 has a bigger carberator opening as well... omg that thing is huge!!!!! Anyway what I wanted to give was evidence to prove the OS.18 did produce more power over the VX.18...hell forums are FULL of people's opinions..however they do most often lack factual evidence. BTW eminent please spit out my head and give it back to me, I can see you chewing on it!!!
On another note, I have found some 3 to 4 shoe clutch designs that fit SG shaft engines, if you guys are interested, below are some links: