pusher vs puller fan ????
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 6,209
Likes: 33
From: Texas-out west
pusher vs puller fan ????
Boss just bought project 58 with LS1 motor, no fan but aluminum radiator...question is, which is better for cooling an electric pusher fan or puller fan? thanks.
Burning Brakes
Joined: Feb 2011
Posts: 849
Likes: 0
From: Woodland California
It doesn't make a vacuum and try to work in it.
The restriction of the radiator it's trying to pull air through
makes it less efficient.
The pusher grabs the air and then trys to force through the radiator.
Ralph
PS, at 25mph and above a fan isn't needed.
Drifting
Joined: Jul 2008
Posts: 1,483
Likes: 459
From: Lititz PA
From a HVAC back ground a pushed works better.
All the outside A/C units I've ever seen have the fan on top. This means that the air is Pulled thru the condensing coils and then forced out the top grill.
I spoke to a tech at a DeWitts booth and he told me they always recommend a pull type electric fan with a shroud.
John
All the outside A/C units I've ever seen have the fan on top. This means that the air is Pulled thru the condensing coils and then forced out the top grill.
I spoke to a tech at a DeWitts booth and he told me they always recommend a pull type electric fan with a shroud.
John
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
This from BeCool
You will find all kinds of references up to 30% better for a puller especially if mounted in a proper shroud. The air is pulled thru all of the radiator instead of being pushed directly in front of the fan with some bouncing around. I use a large pusher as an auxiliary fan for the a/c.
As far as HVAC, 99.9% of condensing units are puller and with air handlers and furnaces, they are usually squirrel cage fans, different ball game. Most air handlers we use here though, even with squirrel cage still pull thru the evaporator.
You will find all kinds of references up to 30% better for a puller especially if mounted in a proper shroud. The air is pulled thru all of the radiator instead of being pushed directly in front of the fan with some bouncing around. I use a large pusher as an auxiliary fan for the a/c.
As far as HVAC, 99.9% of condensing units are puller and with air handlers and furnaces, they are usually squirrel cage fans, different ball game. Most air handlers we use here though, even with squirrel cage still pull thru the evaporator.
Burning Brakes
Joined: Feb 2011
Posts: 849
Likes: 0
From: Woodland California
From a HVAC back ground a pushed works better.
All the outside A/C units I've ever seen have the fan on top. This means that the air is Pulled thru the condensing coils and then forced out the top grill.
I spoke to a tech at a DeWitts booth and he told me they always recommend a pull type electric fan with a shroud.
John
All the outside A/C units I've ever seen have the fan on top. This means that the air is Pulled thru the condensing coils and then forced out the top grill.
I spoke to a tech at a DeWitts booth and he told me they always recommend a pull type electric fan with a shroud.
John
The fan has a chance to work efficiently.
Even the stock fan is 6 inches or more from the radiator.
Condenser unit's blades are feet away from the coil.
Different dynamics altogether.
Ralph
Last edited by Ralphbf; Jul 15, 2012 at 01:36 AM.
Burning Brakes
Joined: Feb 2011
Posts: 849
Likes: 0
From: Woodland California
This from BeCool
You will find all kinds of references up to 30% better for a puller especially if mounted in a proper shroud. The air is pulled thru all of the radiator instead of being pushed directly in front of the fan with some bouncing around. I use a large pusher as an auxiliary fan for the a/c.
You will find all kinds of references up to 30% better for a puller especially if mounted in a proper shroud. The air is pulled thru all of the radiator instead of being pushed directly in front of the fan with some bouncing around. I use a large pusher as an auxiliary fan for the a/c.
Electric fans don't have proper shrouds, that's why they run 2 fans to cover more surface area of the radiator.
Unless you have a plenum you can not pull air equally through a coil or radiator.
These are the style fans I was talking about.
http://www.summitracing.com/parts/BCI-75058/
These would be a whole new ball game.
http://www.summitracing.com/parts/BCI-75007/?rtype=10
There is a chance I may of misspoke.
The blades on the fan made by becool.com look nothing like those on HVAC units
so there characteristics will be different.
Ralph
Last edited by Ralphbf; Jul 15, 2012 at 02:05 AM.
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
btw. I run 16" 3600cfm front and back, cools , no issues.
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Race Director
Joined: May 2003
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From: California
real hard to do with a stock a/c condenser, when I converted to an aftermarket, I inset it inside the radiator mount 1" from the radiator, with some home made mounts that gave enough room to mount a pusher fan to the front of it. According to the aftermarket a/c folks moving it closer actually made both the ac and radiator cool better, and so far it has. 114 degree days toodleing round town and engine temps never get over 180
btw. I run 16" 3600cfm front and back, cools , no issues.
btw. I run 16" 3600cfm front and back, cools , no issues.
very cool.
.. still would love to see some pics!!
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
the rear is on a 180 temp. switch, backed up with a manual override and the front is on a trinary (for the a/c) switch backed up with another temp.switch, and thats backed up with a manual override switch. Also went with two 40amp relays per fan wired in parallel its over kill, but either fan will cool the engine. I'll take some pics monday. Got the grand kid out fishing at skinner.
I came down for some medical b.s. at the VA.
I came down for some medical b.s. at the VA.
Drifting
Joined: Oct 2005
Posts: 1,527
Likes: 148
From: East London/SW Essex UK
A pusher fan even if in a shroud will 'stall' if not able to operate efficiently - a 'puller' fan has to be more efficient as theorically it would be working best and creating a minor vacumn effect within the shroud.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
When I had some crappy 2 fan unit ( don't want to mention the name ) they were pullers. Both came on at the same time. I installed a pusher on the other side in case the pullers packed in. Well they did one time and I am glad I put that pusher on front because I swithced it on and it saved my bacon. I got rid of the condenser because I removed the air conditioning, would have cost me a fortune to bring that up to par since it used the outdated and illegal air conditioning refrigerant.
I then went to a fabrication hot rod shop specializing in cooling systems. They suggested a BeCool rad with 2, 13 Spal puller fans. They fabricated brackets for the fans and I can get by with one fan on the hotest days and I have the option of turning the second one on if I want, but rarely do.
Funny thing was when I went to pick up the rad with fans mounted they were mounted 1/8" off the rad. The shop told me that's the way you want them mounted and not to use a shroud
I then went to a fabrication hot rod shop specializing in cooling systems. They suggested a BeCool rad with 2, 13 Spal puller fans. They fabricated brackets for the fans and I can get by with one fan on the hotest days and I have the option of turning the second one on if I want, but rarely do.
Funny thing was when I went to pick up the rad with fans mounted they were mounted 1/8" off the rad. The shop told me that's the way you want them mounted and not to use a shroud
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
On new cars, you see lots of pullers and a few pushers. Here is something to think about. Our radiators are at an angle, other cars just don't do that. Incoming air is already deflected because of this angle. A pusher fan on our cars, because of that angle, may cause further deflection of incoming air.
If I had A/C, I would do a pusher on it though...
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
Dewitts a vender on here has some excellent tech. on how to run electric fans, and has posted some of it on here, most of the fan mounting systems have mount cushions that keep the fans 1/8" off the radiator, a fan mounted to the radiator doesnt deflect air , it directs it thru the radiator. There are a multitude of different things you can do with electric fans to help cool your engine, in my two years searching for options with my C4, and now my C3, I found that its best to use quality parts, fans, switches, wire sizes, and good grounds, cause the cheap parts dont last.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Ambient in the shade down here can run 105f, and under such conditions with a/c ON or OFF, my ~340 hp 355 roller engine runs normal even in traffic.....
I use a radiator of stock '72 vette core that is listed for a later F body V8, it's aluminum/plastic and single core about 1.25" thick
the Fans are Dual Spal 11" from DeWitt....I let the computer control them, with a light on the dash telling me if they are on or off....they are wired with IGN power to the coil, and FAN power to the Alternator directly....they are puller fans with home made shroud.....setup about a couple inches from the fans to coil.....simple way to do it is, drill some 1/4" holes in the short ends of the horse show/U mounts top and bottom of the rad....and put aluminum angle cross supports, position the fans near the middle, check A arm clearances on each side, and then use household aluminum flashing from the fans to the radiator seams top/bottom/sides and you are sealed into a shroud....
been this way for some years now...no sweat....
I use a radiator of stock '72 vette core that is listed for a later F body V8, it's aluminum/plastic and single core about 1.25" thick
the Fans are Dual Spal 11" from DeWitt....I let the computer control them, with a light on the dash telling me if they are on or off....they are wired with IGN power to the coil, and FAN power to the Alternator directly....they are puller fans with home made shroud.....setup about a couple inches from the fans to coil.....simple way to do it is, drill some 1/4" holes in the short ends of the horse show/U mounts top and bottom of the rad....and put aluminum angle cross supports, position the fans near the middle, check A arm clearances on each side, and then use household aluminum flashing from the fans to the radiator seams top/bottom/sides and you are sealed into a shroud....
been this way for some years now...no sweat....