Originally Posted by
Conrad
I know it will spoil the aerodynamics a bit but a large (35mm) hole in your front windscreen and a smaller hole in the rear window (30mm) in line with your esc/motor will reduce your running temps by quite a bit. I tested this indoors at my club (tc and mardave on carpet with foams, stock motors, ~20'c hall temps) about a year ago and have run it ever since. I was looking at a couple of degree ('c) drop with one hole at the front or back but with both open it dropped the temps by about 5'c.
This was without any extra passive or active cooling on the motor, just the extra airflow through the body. If you feel the rear window of your shell before you remove it from the car it will be quite warm
Ok this solution isn't the best as its not legal for running in big races but we do allow it at our club and its easy to tape up the holes when running elsewhere.
Forced air cooling
We run on a long outdoor track in heats of 100 F with track temps 140 F or higher some times in the summer. Following up on Conrad's work but staying within the ROAR rules was my goal.
First the rules
6.1.10 Openings in the body other than those appropriate to full-size vehicle openings such
as grill, scoops, air vents, etc., must be kept to a minimum. Specifically servos,
receivers, batteries, and servo savers are not allowed to protrude through the original body shell.
8.10.5.7 Body rules:
No windows may be cut out.
You can put a scoop in, in other words, but not in the glass area of an electric car body. Other penetrations should be kept to a minimum. Typical scoops you see on Lemas race cars enter the grille, sometimes centered on the hood, brake scoops on the sides. You cannot exceed width limits with a tall brake scoop on the side.
I went to the auto parts store looking for blister packs of a suitable shape. The Dualist winshield wiper package provided the scoop almost fully formed. I trimmed it to fit the winshield so as to force air down through some penny sized holes in the top of the hood. The air enters a four sided rectangular smooth channel from a different brand of wiper blade. (These were in the garbage can outside). Some blister packages have four plastic sides this may work better inside the car. I used a plastic over cardstock package. I mounted the duct by bridging the hood to the deck lid. I used four tiny 2 x 56 screws to hold the vent and 2 to hold the scoop on. I sealed the very back end of the vent. It will be a maintenance hole to install some plastic shipping tube tops in the duct's exit holes.
You can see one of the exit holes above the speed controller in the pic. I plan to install a clear plastic tube from a machine tool shipping package. I will be using the press on tops (with new big hole) to push through my hole from the inside. Then my clear 1 inch tube will press on over this. Pic tomorrow. I tested with a hair drier and got a good stream of air out of my holes. On the track you will get some 55 mph air going directly to the motor and speed controller.
This system is working great on my wide pan car which is drawing an average of 50 amps during a run these days. I use no fans!
Our new asphalt and layout beg for a 3.5 in the TC5. I put the Novak Ballistic 3.5 motor back in the car. The high speed, cooler than track surface air, should help the car make the 6 minute mark.
I left one fan installed as I hated to cut the wires on a working LRP fan. It will help during periods when the car is stopped at the end of a run, at the beginning after a practice lap (and when the car is on its lid after getting punted into the wall)