First, there are no 3 volt motors.  Those who already understand this can skip a few paragraphs.
There are motors that run on 3 volts while providing acceptable performance and lifetime.  The same motors may also run on 1.5 volts and on 6 volts, providing different performance and lifetime. 

This started in the early days of slot cars when the cars used model train motors.  A 12 volt motor was ok until the day someone showed up with the same motor but in a 6 volt version and won the race.  Begun, these voltage wars have, Yoda would say.  4.5 volt, 3 volt, and even wilder claims quickly cropped up until it got silly and finally the manufacturers started providing some meaningful information like the wire size and number of turns.  This was a good way to directly compare potential motor performance and the voltage wars ended.

Slot car motors can all be considered 12 volt motors by definition since the track is powered with 12 volts.  Motors range from slow (long lifetime, $10) to incredibly fast (15 minute lifetime, $300+).  The performance and lifetime  are acceptable depending on the application, so much for a "12 volt motor".

***End of lesson.

Most of our motors have 0.18 mm wire and are most likely a custom product, a cross between a Mabuchi FA-130RA-18100 and the FC-130 version with carbon brushes instead of metal for longer life. The motor is rated for a speed of 9710 rpm, drawing 0.56 amps, and power of 0.76 watts (at maximum efficiency).  This $2 (retail) motor is our baseline for power and battery life.  Here is a data sheet for the Mabuchi FA-130:


The motor can be run at more than 3 V but not for long, here is a test of these motors at varying voltages:  http://www.pololu.com/docs/pdf/0J11/tamiya_toy_testing.pdf
For those that don't want to read the entire article: running the motor at a higher voltage can burn it out in little more than an hour.  One thing I found is that our motor (or at least the one I took apart) has better brushes than the ones in the article and may survive for awhile with the higher voltage.

There are many motors in the FA-130 size with varying performance.  Tamiya produces a line of small RC cars and offers numerous inexpensive motors for them, from one that is probably just like our monorail motor to some that should give over twice the speed while draining the batteries three or four times faster.  You play, you pay! 

Tamiya's top of the line $10-$15 Plasma Dash motor has a number of upgrades over the $2 FA-130: a real commutator; a metal bushing in the endbell instead of plastic; replaceable brushes; cooling slots; stronger magnets;  The Plasma Dash is wound with 0.35 mm wire and draws 4 amps!  This one will go fast but the batteries will probably be drained in a few minutes *if* the fuse does not blow and *if* the motor controller (in the remote version of the monorail) can provide enough power.  One person wrote to me and said that in his experience it will not.

Tamiya's "Torque Tuned" motor (less than $10) shows a great performance increase when used with a stock gearbox, even more when used with my regeared gearbox. Other Tamiya motors such as "Rev Tuned" may be a good compromise between power and battery life, I may be testing some of these soon. All the Tamiya motors with the exception of Plasma Dash appear to be variations on the FA-130, apparently just a change in the windings and maybe the timing. Btw, timed motors turn faster in one direction, run them backwards and performance will be poor!

All of the Tamiya motors that I have opened except Plasma Dash (Torque Tuned, Rev Tuned, Atomic Tuned) also have metal brushes and will probably not last long.

There is a class of slot car motors called "Euro" that have the same dimensions as the FA-130. These are made to run on 12 V and most of them draw far too much current to be of interest to us. Some, however are made to replace the motors in a home racing set and draw less current. Some versions have high quality magnets and brush setups, none that I have tried will run fast enough (on 3 V) to work in our monorails. Price is somewhere between Tamiya and precision, about $15.

Next, the Kyosho Mini-Z race cars also use 130 size motors. These cars run on 4xAAA cells but some of the motors run fast enough on 2xAA to work in our monorails. Motors go from mild to wild, some have ball bearings and neo magnets (for a price). The 80 turn and 50 turn are probably as wild as we need to go.

There are also more efficient motors (Faulhaber and Maxon) that provide twice the performance *and* with the same battery lifetime!  These precision motors cost about $60 compared to the original motor at $2.  You play, you pay, 2.0!

On to the "motors 2" article for a more updated and in-depth look at the FA/FC-130.