Thread: Derale 12" Radiator Fans

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Will this fan develop the same CFM when reversed and used as a puller? On every site I've found these, they indicate to be used as pusher only, but the Derale site indicates they can be used as puller when mounting to your own shroud,which is what I have made for the 65 El Camino.

Another odd question. Just because I install two of these, the CFM remains the same...correct? Its just displaced over more area....correct? I've got a fellow telling me two of these will be good for 4300 CFM. It just didnt sound right so I waited until
I talked with my fellow CHR members before ordering.

The ones that are dual setups with shroud wont work.....I'm limited to 25" in width.


From Derale's site:

Part #16925 High Output Single Rad Fan Reversable

. Injection molded fan housing with stator flow directors
. High output 265 watt motor
. 2150 CFM
. Pusher (grill side) applications only *can be used in puller application
when custom shroud is used.

I'm wanting the most CFM I can muster with a pair of 12" puller fans bought and mounted as single units.

Pushers are not as efficient as pullers, especially if you take what one once a puller and reverse the current to make it spin backwards. The blades have a dish to them and that should always face the rear. I think you will see when you put your fan up front the dish will be facing the front. In that instance the efficiency is about 50% of the fans rating. However, a fan that was built to be a pusher will be slightly higher due to having the correct blade shape from the get go.

Also, when you use two small fans they are generally not equal to one large fan.

Don

Sorry this post isn't a answer directly to your question.We have found on the swaps for V8's in Astro vans,it's hard to beat the 14" fan from a Crown Vic.You have to run a relay because it draws so much.

One thing the fan companies do not tell you is the static pressure drop of CFM once the fans are attached to the radiator. If you see a fan advertised at say 4000 CFM, yea it will pull 4000CFM if you hook it up and hold it over your head, but take and attach it to the radiator and now the static pressure drop happens,that really lowers CFM.
We did a test on a brand name fan advertising 4200CFM. After attaching it to the radiator and measuring CFM drop, it pulled 1100 CFM.
The best results for static pressure drop is the Spal fans. They advertise 2750CFM and after bolted to radiator, CFM dropped 400 to 2350.
A true pusher fan will work where a puller cant be used. But it must be a true pusher, not a puller with the blades turned and rewire the motor.

Everything I've seen on aftermarket fans says that SPAL is at the top of the heap for quality and performance, especially if you spring for their programmable controller and temp sensor as a total package. Go to their website to get started, but then you can call their tech line to get one-on-one guidance for selection, and for any operating questions that might arise. A top notch company, in my book.
Like Gary says, a lot of folks have done well using OEM fans from Fords - seen lots of Taurus fans with using OEM relays for a low buck approach that seems to work, and there are lots of them out there.

SPAL fans certainly have my vote as being the best. I have used a bunch of other brands and when I got my first SPAL and turned it on while holding it in my hands it almost took off on it's own. It moved a lot more air than any fan I have ever had, and the life expectancy is much better............I don't think I have ever had one fail, even after years of use.

Years ago I had a conversation with the President of PRC radiators at Turkey Run and he said they regularly test every fan on the market and SPAL consistently out flowed them all.

Don

Great info everyone. Thanks so much.

I have a fan assembly out of a Crown Victoria but want to keep it for the 36 I think. I bought a overseas fan...F.F. Dynamics 16" 3000CFM fan off of Ebay for the boys 65 but neither of us care for the red housing and I was worried about painting it and expecting the paint to stay. Does anyone know anything about F.F.Dynamics? Do they outsource overseas? Just curious. Couldnt get any solid information from their site.

My son mentioned he wanted to go with dual 12's and a controller. I really like the SPAL's but their 12" pullers mounting width is 15+inches. I'm limited to 25 inches over all. I'll call them and find out what their highest rated fan in a 11" puller is. The next in line was the Derale Ultra Extreme 12" pullers. Mounting width is spot on 12.25". Two of these would work great but only move 2150 CFM and are pushers.

I'll do some more digging and let everyone know what I find. I may just tell my son we're staying with what we have.

The biggest part of a cooling system is the shroud.

Remember .......if a company sells a fan without saying it is a true pusher...it's a puller. And it will not work well as a pusher if you have to turn the blades around and rewire it to run as a pusher.
Again.......Spal makes a true pusher or a true puller...they won't sell a puller and tell you to turn the blades.
Spal is also factory on the new Ferraris..........there web site is..........Spal-USA.com
When measuring for space for a fan, always give yourself at least 4 inches extra from where it attaches to the radiator to the front of the motor. Always look for the HP after the fan number. Spal mkes lots of fans but the HP versions are meant for the hot rod motors.
Using fans from some stock applications may work ok, but the downside is those fans are meant to cool the HP of that motor. You need to have a fan that will cool HP.
I can tell you that a twin 11in fan setup from Spal will need 24 inches of finned area of the radiator to fit it.
And finally...........I don't work for Spal.........I work for Evans cooling............but we do talk to people all day and tell them the same thing about Spal fans.

i have found over the years that the #1 reason for heat problems is rad thickness. i went to a z-core back in 90 with an original 47 rad. you could see through it and only 2 3/8 in thick. was able to move much more air at idle. sold the walker to the first person i could and have not owned one since. since then i have switched to aluminum rads and the flexlite cyclone fan . my shop truck will have a ford factory electric fan from a 94 tbird. thing is like a helicopter but draws a lot of amps.

Thanks guys. I spoke with SPAL and the only one that fits my needs will be the 11's. I see what you mean by the amount of surface area needed for the 11's, so the SPAL's wont work for me unless I go with the single 16 which I may do.

I've even concidered converting back to a clutch/fan combo. The Chevelle/El Camino rad was simple to make a shroud for. I bought the radiator from Champion and I'm very happy with the radiator itself. I'll be able to mount a flat piece of aluminum with a bend at top and bottom. I've got a 16" fan mounted directly to the radiator at the moment but it make me uneasy mounting it this way if my son is going to be driving this thing all the time. So yes I'm mounting it to a shroud soon.

Shine, I know what you mean by the radiators. My son's car has a heck of a cooling issue. Its on the verge of detonation as it is which makes it even harder with cooling. I went with the aluminum radiator and it instantly dropped in temperature but I'm sure it was in how they designed it....as they staggered the rows slightly. Prior to the change to the aluminum it had a 4 row factory style radiator and I just couldnt cool it no matter what I did. Cooling it know is no longer an issue even on the hottest of days. I may back the timing off a bit more.

Thanks again guys. Your help inspires all sorts of ideas and anyone digging for info may see this thread later.

David