Improvement #2: cooling the motors - Air

Air flow through the tight spaces of the motor is difficult but might be the difference between the windings failing or surviving.


The inside of the Siemens has some dead air spaces. These air spaces surround the bends in the copper windings. Where the wire bends will be the hottest part of the windings.

wire in dead air space  

We want to get air flow through the dead air spaces to cool the windings.

Rotor removed  

There is a molded web that supports the rotor. This area also mounts the position sensor.

The way the support web is cast, blocks any air flow.

web supporting rotor  
We drill holes large enough to get a grinding head in, and then open up the holes.  
opening up the holes  
When we are finished, the motor end is still strong but there are openings to allow air flow.  
air flow seen from inside motor  
We drill and tap four holes in the motor face.  
drill and tap for fan  
Cut a face plate to hold the fan.  
face plate to hold the fan  
Check that everything fits.  
ready for installation  
And bolt on the fan to pull out air.  
fan ready to pull out warm air  
The other end of the motor has a flat plate.  
motor face pre holes  
We drill as many holes as we can without compromising the support of the rotor.  
holes drilled and covered with tape  
Since we are now flowing air through what was once a sealed motor, we need to think about grit getting in the motor.  

We replace the bearings which have only a metal dust shield with fully sealed bearings. The fully sealed bearing exhibit slightly more drag.

Since we expect to run the motor at its upper heat limits, we also replace the stock grease with high temperature Redline moly grease (rated for 800 C) and reinstall the seals.

Using a K&N high flow air filter and Plasti Dip, we cut and mold custom filters which mount over the air intake side of the motor.

filter being installed over air intake holes  
We modify the engine mounting plate to hold the filter.  
engine mounting plate with lip to hold filter in place  

Then we install the motor.

Air is sucked in through the filter,...

motor in place with filter installed  
...and exhausted through the fan (red safety plate installed until use).  
fan installed with red safety cover  


 Improvement #2 cooling the motors -Solid
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