Fan on Motor, Speedo or Both?

Hello,

I've got a 1897 and I use it with a 10L and a 9L. Just starting to understand gearing as I've had lots of heat problems this summer. My original 9L died after hitting 200+ degrees after each 5 min run.

Now I've got a fan on the motor, I switched to the 10L and geared it so I'm not yanking full throttle everywhere and my motor temps are good. Last 5 min race was about 165 degrees.

My (long winded) question is, do I need to put a fan on the speed control? Which is more important, putting a fan on the motor or Speedo - or both? And if you put a fan on the Speed Control, which direction do you want the airflow, blowing down on the speed control or blowing up as if to remove heat from the heatsink?

I also just installed one of the awesome RC-Monster Heatsink's on my 10L, I've not run with that installed so maybe it will make my motor even cooler!

Any help would be appreciated.

[maxxdude1234]

Wow, 200*F is pretty toasty. If your motor's at running 165*F that should be fine. Once you've got the heatsink on it that should drop by a good 10*F or so. If you can get any airflow (holes in windshield) over the motor this will help, but it will also add a bit of drag. After a good 20minute run my motor gets upto 175*F, so 165*F shouldn't be a problem.

How hot does your speed control get? It might be worth putting a small fan over the heatsink (you'll want the air blowing onto the heatsink.

[Serum]

The fan on your schulze can't be big enough imo.

Best way to let the air flow blow instead of sucking, decompressed air can't transport as much heat than compressed air.

Thanks for the tips guys. So do you typically have the fan pointing straight down over the Speedo heatsink or do you try to put it in front of the heatsink so it is blowing sort of through the fins? With the motor temps in the normal range, I want to be sure I don't have thermal problems so cooling the speedo is my new challenge.

Thanks,

[Serum]

I want to be sure I don't have thermal problems

I only drove my schulze once without a thermal.. I had two 18.97 and both controller suffered this problem. Normally a little bit of airflow is enough to cool the controller, but with a schulze you simple need a large fan. and make some kind of a duct.

[RC-Monster Mike]

The 18.97 with a 10L may not even need a fan most of the time, but it is always a good idea. Mount the fan so it blows air over the heatsinks (down or through doesn't matter, as long as it blows the air onto the heatsink) and you will be perfectly fine. Here is another tip-the heatsink fins onm my clamp will accept a 2mm threaded screw between them, so you could mount a fan to the heatsink using these screws to hold it in place.
165 degrees is not terribly warm for a hot summer day on a race track, either.

Thanks for the reply. Great design to make the fins accept a screw, I'll most certainly make use of that.

I'm going to move the fan to bow on the speedo and check temps this weekend. Just worried I guess, when air temp above 90, I'm worried, guess that's what happens when you loose a race b/c of a thermal (it was a huge lead...really...still finished 4th)

So Mike, any chance you are going to come to Xtreme tomorrow? Like a MM warm up race? I hear they changed the track so we all should be on equal footing. Hope you and your crew can make it.

I've got some results from racing yesterday...

I made two changes to the truck, first this was my first run with the RC-Monster Heatsink/clamp. I also moved the fan to the speedo. I moved the fan for two reasons, the last time I ran, the motor was cool at about 170 degrees. I had a Trinity heatsink on it with the fan blowing air up from the bottom. I didn't have a fan on my speedo which was hitting 140-145 degrees. Too hot for comfort. So I moved it. I had the fan RIGHT on top of the speedo and as posts in this thread suggested, I had the air flowing right DOWN onto the speedo.

Good news - the speedo was temping about 120-125 degrees after installing the fan...much more comfortable and safe.

Bad news - the 10L motor was way hot at 200-210 degrees. I need a second fan for the motor...rats. I'm just not sure I don't have some other problem like my gearing (10L, 14 cells, Gorilla 1 speed conversion {so I'm in 2nd}, 64 tooth spur, 16 tooth pinion.) I hit full throttle at about 3 or 4 places on the track just for a second or two. I can't imagine gearing it taller but I've read elsewhere the reason for the high temps is the high RPM at full throttle. Other possibility is the settings on my 1897 speedo...I've set the DIP switches as per what I "think" is right but no one has ever been able to tell me the right settings with confidence.

Hope the fan cools things down...