R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 06-19-2006, 10:29 AM   #1
Tech Initiate
 
Join Date: Jul 2003
Posts: 29
Default Motor heatsink fan - push or pull?

I just purchased a 3 Racing motor heatsink with fan. The fan is set up to pull air away from the heatsink. I found this strange, since to my thinking, it would be best pushing air onto the heatsink to cool it. It is easy enough to turn the fan over if I want to push air onto the heatsink instead of pull air away...

Can anyone tell me if the fan should be blowing air onto the heatsink, or pulling air away from it?

Thank you.
lush is offline   Reply With Quote
Old 06-19-2006, 10:39 AM   #2
Tech Master
 
Join Date: May 2003
Location: UK
Posts: 1,244
Default

Quote:
Originally Posted by lush
I just purchased a 3 Racing motor heatsink with fan. The fan is set up to pull air away from the heatsink. I found this strange, since to my thinking, it would be best pushing air onto the heatsink to cool it. It is easy enough to turn the fan over if I want to push air onto the heatsink instead of pull air away...

Can anyone tell me if the fan should be blowing air onto the heatsink, or pulling air away from it?

Thank you.
if you got the motor over the heatsink ie on the can holes then you want it facing away because the motor pushes out the hot air threw the can holes.the motor will just be pushing it back in,but the fan isnt powerfull enuff so wont do anything.
alot of people undo the scews then screw it back on with the heatsink on and the fan blowing on the endbell,which is were the air is sucked in.
change the fan unit on it,it isnt that powerfull.
__________________
Tamiya
Much More Racing
LRP electronic
Futaba
Speedtechrc
trf racer is offline   Reply With Quote
Old 06-19-2006, 10:55 AM   #3
Tech Initiate
 
Join Date: Jul 2003
Posts: 29
Default

Thanks. Would I find more performance benefit with the fan blowing on the endbell, or sucking from the can?
lush is offline   Reply With Quote
Old 06-19-2006, 11:04 AM   #4
Tech Apprentice
 
scottwk1's Avatar
 
Join Date: Mar 2006
Posts: 61
Default

From a computer standpoint, if you blow the fan into the heat sink the chip can run hotter as you are blowing the hot air in the case back into the chip. The heat sinks were designed to have the cooler air come in the sides and change to warm and suck it back out where the fan in the rear expells it. If the cars follow the same suit, it's better to have it blow out instead of in, but with the size of the fan and the heat sink, it may not make that much difference.
scottwk1 is offline   Reply With Quote
Old 06-19-2006, 11:09 AM   #5
Tech Master
 
Join Date: May 2003
Location: UK
Posts: 1,244
Default

Quote:
Originally Posted by lush
Thanks. Would I find more performance benefit with the fan blowing on the endbell, or sucking from the can?

you wont necesarily get more performance but what you will get is a much more consistant performance from start to end,also brushes will be cooloer and last a bit longer.
less heat=more effeciancy=more power for longer.
a fan wont keep a motor cold under usage,it will stabalize the temp and performance though
__________________
Tamiya
Much More Racing
LRP electronic
Futaba
Speedtechrc
trf racer is offline   Reply With Quote
Old 06-19-2006, 11:09 AM   #6
Tech Champion
 
Jon Kerr's Avatar
 
Join Date: Jul 2002
Location: San Diego
Posts: 9,658
Trader Rating: 17 (100%+)
Default

The fans we use aren't powerful enough to draw anything away from a heat sink. I have the same heat sink/fan unit and I replaced the fan with a Novak one and flipped it over and hung it out over the end bell. The heat sink can draw some heat away and act as a mount for the fan to blow air onto the end bell.
Jon Kerr is offline   Reply With Quote
Old 06-19-2006, 06:30 PM   #7
Tech Addict
 
AngryAsian's Avatar
 
Join Date: Oct 2005
Location: Melbourne, Australia
Posts: 550
Trader Rating: 4 (100%+)
Default

The 3racing heatsink/fan units are poorly designed.

I admit i got a bit excited and bought one out of curiosity. The fan is very weak and mounted too far away from the heatsink itself to do any useful work. Also, like many heatsinks there isn't much base aera to trasfer heat into the heatsink itself...

Your best bet is to take the screws and spacers out and flip the fan...
The fan just isn't strong enough to increase the airflow going over the heatsink when it's "sucking"... This puts the fan closer, and moves more air over the heatsink.

If the heatsink covers the motor vents and you're certain the air is supposed to be expelled here then leave it...
(I always though air came IN the can vents, and out the endbell vents on both sides - but that's just a blind guess really)

A better solution is to mount a much more racing fan on there.. Much higher airflow.

The biggest problem with a fan that "sucks" is that it needs to be cowled to really do anything. That is.. there needs to be an almost flush fitting ring around it otherwsie it just takes air that is near the fan are forms a convection current.
AngryAsian is offline   Reply With Quote
Old 06-19-2006, 09:38 PM   #8
Tech Champion
 
C_O_jones's Avatar
 
Join Date: Oct 2004
Location: Wa.
Posts: 9,055
Trader Rating: 11 (100%+)
Default

The 3racing fan is pretty weak when run from the reciever, run it off the batt and it's much better.
I soldered the wires from the plug to the batt cons on the speedo and still have the plug to use as a switch. but do flip it over and hang it off the end over the endbell.
__________________
Bacon is Meat Candy
C_O_jones is offline   Reply With Quote
Old 06-19-2006, 10:23 PM   #9
Tech Master
 
Join Date: Mar 2004
Location: Earth
Posts: 1,039
Send a message via ICQ to rcnewb2004
Default

Short Answer, Blow air onto the heat sink. It's easy to do, and easy to find if its working.

As mentioned before, a lot more considerations need to be made if u are sucking air from the heat sink.
rcnewb2004 is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB:heatsink/fan for motor and a temp gun Snipesr82 R/C Items: Wanted to Buy 0 09-06-2007 09:09 PM
Motor heatsink with fan ( NIB ). rc_freak R/C Items: For Sale/Trade 4 11-27-2006 01:32 PM
Where to find motor heatsink? grymg Electric On-Road 4 07-20-2005 11:40 AM
WTB: TC3 Parts,Battery and Motor Case, Motor Tubes, Heatsink w/ Fan BSchorr R/C Items: Wanted to Buy 11 03-05-2005 01:01 PM
Associated motor heatsink - FS jonski R/C Items: For Sale/Trade 1 03-02-2003 11:32 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 10:26 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net