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Old 03-29-2009, 11:03 PM   #1
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Default active cooling

So today (my first time racing on an actual track) I saw a lot of new things. One thing that really stuck out to me was some of the active cooling systems people had on their cars. There were huge heat sinks on top of both motors and esc's with 1-2 fans. One guy even made a mount that placed his ESC at an angle so the esc was tilted forward to give it improved airflow.

I know a lot of esc's come with fans and a lot don't. Besides the obvious of keeping things cooler, what is the gain? By keeping things cooler, are you able to get more speed? Is it just a longevity thing?

I was under the assumption that if you are properly geared, cooling should not be an issue.

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Old 03-29-2009, 11:11 PM   #2
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Electronics also run more efficiently when they're cool.
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Old 03-29-2009, 11:17 PM   #3
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Heat is the enemy of electronics and motors. But I dont run any fan
in any of my cars... well except for my LRP Sphere (built-in). I think fans
suck up current from battery, plus add the power hungry digital servo,
which means your motor isnt getting all the power. Runtime is also
reduced.
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Old 03-29-2009, 11:27 PM   #4
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The draw from 99% of fans won't have an impact on driving power, and while my Novak GTB fan doesn't say it's power draw on it, most 120mm computer fans will only draw 250mA... So not a big hit on run time, either, with those little tiny fans
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Old 03-29-2009, 11:59 PM   #5
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I have a shorter runtime with a car using a fan-equipped ESC.
I also know some people who use GTBs and just removed the fan
because of easily shatered blades from road debris.

Compute the weight of the ESC fan and its wires and plugs, the dual
fan in the motor heatsink, how many grams? The cost to replace them
once they're shattered or damaged. Theyre unnecessary really.
Just gear properly.
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Old 03-30-2009, 12:26 AM   #6
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I think it depends on what you run for a motor... For anything 13.5 and lower, or even 10.5 and lower, I wouldn't worry about the ESC working too hard...

I don't think my GTB heatsink has ever gotten over 90*F, and it's only got 1 or 2 blades left on the fan

And that's at pretty much full-throttle running for 7 minutes... The motor is a little warmer, though.
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Old 03-30-2009, 12:49 AM   #7
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This is really easy. Take your car with the fan, run it, take the temperature. Take the fan off, do the same and compare the two temperature readings.

I think for the most part cooling fans are items that someone put on their product and then everybody had to do it so they don't look like behind the technology. There may be situations where they are needed but I think a good heatsink is going to help more than any fan.
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Old 03-30-2009, 01:20 AM   #8
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Airflow has a lot to do with it too... If there's no air flow inside the body, then there's no real place for the heat to go.
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Old 03-30-2009, 10:32 AM   #9
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One example.

I was running stadium truck on an indoor carpet oval. Class was 6-cell/2S LiPo and 19T brushed or 10.5 brushless motors. I run the 19T.

Adding a fan over the motor meant I could go up 1-2 teeth on the pinion with the same motor temps and made the truck faster.
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Old 03-30-2009, 11:22 AM   #10
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Ultimately if geared properly you won't need a fan. But I can see if you run outdoors in hot weather fans could be necessary...especially with low wind motors. Using fans do make a significant change in temps. I used to see 15-20 degree differences in temps when running a fan. When I ran a fan I would gear so I would come off the track at less than 170. But even though my temps were OK I would still notice a fade during the end of my runs. This was probably due to the internal temps of the motor being too high. So I took the fans off and geared accordingly and I was actually faster when geared right with no fans.
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Old 04-12-2009, 01:47 PM   #11
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Quote:
Originally Posted by drperry View Post
Airflow has a lot to do with it too... If there's no air flow inside the body, then there's no real place for the heat to go.
I think this is really key. Good airflow would do better than a good fan, if not better. Good air flow and a fan wood be ideal if needed.


So my next question,

Has anyone tried opening up their windshield on their body to increase airflow? Maybe even add some sort of duct to get the air flowing right at the esc/motor. As I look at my body, I can see how air can easily escape, but not enter.

Would a whole in the windshield mess with aerodynamics too much? I can't believe it would, the nitro guys do it.

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Old 04-12-2009, 01:58 PM   #12
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I'm sure it's helped a lot on my E-Jato conversion...

I don't think my motor's ever gotten over 100*F, and I can wheelie like no tomorrow (provided I have traction) and I think the closest I get to top speed is maybe 50% on the straights.
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Old 04-12-2009, 02:09 PM   #13
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I have a body I don't mind butchering up. I geared and timed my car to where I am around the track the fastest and I am pushing the threshold of heat limit. It was a hot day, but I'd like to have some room for just in case.

I'll post my results Tuesday when I get back from the track.

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Old 04-12-2009, 02:26 PM   #14
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I also don't have a heat sink on my Jato, and I'm pushing probably, at least 1.5 - 2 times the weight due to the 3mm thick solid aluminum chassis

Just put a hole like the nitros have inline for the motor or ESC... Whichever is getting the hottest... Maybe a 3/4 - 1" across if you make a round hole, or if you go the square route, about that length on each side...

Come summer time, I'm probably going to be sticking a heat sink on my motor just to be safe.
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Old 04-12-2009, 09:34 PM   #15
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Quote:
Originally Posted by pakk View Post
I think this is really key. Good airflow would do better than a good fan, if not better. Good air flow and a fan wood be ideal if needed.


So my next question,

Has anyone tried opening up their windshield on their body to increase airflow? Maybe even add some sort of duct to get the air flowing right at the esc/motor. As I look at my body, I can see how air can easily escape, but not enter.

Would a whole in the windshield mess with aerodynamics too much? I can't believe it would, the nitro guys do it.

--pakk
Just as a reminder though, competition 1/10 EP touring class does not allow the bodyshell be cut excessively (eg: cutting windshields and all)... Its against the rules set by IFMAR...

However for bashing purposes, you may go ahead and experiment...
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