the typical motor used is the 55t integy lather motor - its supposed to be a compromise between integy's alterntive 45t and 65t lathe motors and should be good for around 10k rpm max and loads of torque. more turns means fewer RPm and more torque, fewer turns means more RPM and less torque.
as for which is best, it depends mainly on the gearing available to you, if your trying to crawl with something like a TL01 where your stuck to a 7.96:1 gear ratio you want as many turns as possible to bring the wheel speed down - yet for a custom rig running a pede tranny and TLT axles you have many gearing options and could get away with a 27t silver can.... assuming you gear down suitably for the kind of speed and torque you want...
it will also depend on what you want from the rig - some folk find even 45t lathe motors too slow for their expectations, others cant get enough low down torque from 80t LRP truck pullers...
:truck
