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[NEW2elec]

As I watch videos and hear people talk about the bottlenecks for electric performance at high speed, heat seems to be the killer.  Liquid cooling works for normal road use but it adds weight and another system to maintain or fail.  Zero has bypassed this for air cooling along with their IPM rotor setup.
Now I'm thinking racing.  Drag racing most likely.
What if you used either a CO2 tire cartridge or even a small paint gun tank to quick cool the motor.
Ideally a hollow vented port in the motor shaft itself venting through small release valves at the motor surface.
Perhaps a threaded housing that screws into a puncture point after so many shaft rotations?
Maybe a push button release valve on the handle like a NOS release. 

[Erasmo]

For drag racing you're already way over the finish line before you need to think about cooling an electric motor.

[NEW2elec]

Well Dr Bass talked about going double 660 amp controllers
A stock Zero wouldn't need it.  But a stock Zero is only beating stock "sporty" cars.
I'm looking for sub 10 sec rides.

[NEW2elec]

Maybe a pike's peak type hill climb or short lap time.

[Doug S]

For drag racing, if you need to cool, use ice. That's what the drag racers do. For Pike's Peak, ice -- that's what Brandon does. For longer-term racing, you'll need to go to water cooling or engineer a very good flow of air over the motor. There's nothing wrong with air cooling; if you think about it, the radiator on a water-cooled system is just another way of dumping the heat to the air. A radiator just allows you to put the cooling where you want it and maybe offers more surface area.

When I was at General Dynamics, we were working on infrared detectors which needed to be very cold; we used a cryostat using expanding CO2 just as you describe. But the bottle was heavy, it was dangerous (as any highly pressurized bottle is), and it lasted maybe a full minute. The calories of heat you can absorb that way just aren't worth it.

Someone once suggested slowly spraying (misting, really) water on the motor, which might work. Water absorbs a ton of heat as it evaporates. I'd worry about the motor being totally watertight, especially the bearings, but it might be okay.

[NEW2elec]

Well my understanding was you wanted the magnets cooler.  Misting the motor surface seems like merely a slow bleed of heat through the winding and outer shell with the magnets suffering in the center.

When I was young we had a pellet pistol that had a bad seal so when you punctured the CO2 cartridge it just went off and when you dropped it out it was so cold you couldn't hold it.

Just plain ice is weak.  Try a hand cranking ice cream maker without the rock salt (grandma warned me it wouldn't work but just couldn't say no).  I got cool sweet cream, which was not a total fail in my 5 year old book.

Maybe a spring forced dry ice tank pushing through the motor shaft venting around the magnets. 

Now this is not practical for normal use but this is racing which is a money pit to begin with.
What amount of effort or price can be put on glory?   

[rayivers]

If one would be willing to unseal their motor casing, a tiny 10-15 cfm DC blower / air filter / two properly-placed holes (blower in, hot air out) in the RH motor end plate would greatly increase the time to rotor overheating, possibly eliminating it entirely for most street riding.  Of course this would make little noticeable difference in operation in a Zero unless the thermal-strategy sensing thermistor range was adjusted, preferably using exit airflow temp and a ranging nomograph.  Yes, the coils would get hotter, TBD by measurement - with continuous internal & external ambient airflow I doubt it would ever get anywhere close to the wire-insulation limits, which can range from 300C to 1200C.

Ray

[Doug S]

Well my understanding was you wanted the magnets cooler.

You're right about that, even with the new IPM motor on the Zero, the magnets are probably going to feel the heat before anything else. There are solutions for that -- search "ferrofluid" on this forum for my favorite. Another good one is filling the motor half full of Automatic Transmission Fluid (ATF). Either of those will greatly assist in getting heat out of the rotor. Racers have also sometimes simply ventilated their motors by drilling holes through the sideplates of their motors to allow lots of cooling air inside. I believe Burton has a bike that's been modified that way?

But other than direct ventilation (which isn't really suitable for a daily driver), these techniques just transfer the heat from the rotor to the stator. Ultimately, you'll have to get the heat out of the stator and dump it to the atmosphere, at which point the techniques we're discussing come into play.

[Erasmo]

You could experiment with pouring liquid nitrogen or emptying a CO2 extinguisher pre-drag to supercool the motor through and through, but that could effect other parts like glue etc that aren't made to deal with temperatures of -200.