General rad fan question for my 56

[samdjr74]

Hi All,

I need to get a fan for my radiator. I'm running a 350 pushing around 400hp, a 700R4 behind it and the radiator is a 4 core aluminum with the trans cooler built in. My question is, is there a rule of thumb on how many CFM's my fan should be pulling per HP or displacement? I don't have A/C in the truck now but I might sometime down the road. The issue I'm running into is the space between the pulley and the radiator is very tight, a little over 3" so I'm limited to what I can do. I found 1 dual electric puller but it's only 1600CFM's and I'm a little worried that it might no be enough. Any help would be great.

Thanks,
Sam

[GCncsuHD]

1600 is definitely low. That is plenty for a stock manual SBC, but with 400HP and an Auto I would look closer to 2500+, if you would be adding AC you are going to want to add another 1000CFM just for that. Whatever you do, build a shroud for it to be the most efficient, all the CFM in the world isn't worth a thing if it's not utilizing all of the radiator's area.

[55metalmonkey]

dumb question but are you running with a shroud and mechanical fan? without the shroud the fan would move much less air through the rad.

I agree, 1600 cfm seems a bit low, bigger better IMO (in most cases)

[samdjr74]

Not a dumb question at all. If I was going with a mechanical fan then yes or even a single electric fan, I would use a shroud. But I'm looking at dual electric fans that have the built in shroud that covers the entire radiator.

My problem right now is the size. The radiator isn't for a 56, not sure what it's for, it was sold as a 55-59 and I go it real cheap but it's new and aluminum so I plan to use it. But the radiator itself is 25 1/2" wide with 1 1/2" mounting bracket on each side for an electric fan. It's 16" tall for the core area and 21 1/4" overall high. The problem is the distance between the radiator and the bolts on the water pump pulley, I only have 3 3/8" between the 2. So far finding a fan that will fit is a little tough.

Originally Posted by 55metalmonkey

dumb question but are you running with a shroud and mechanical fan? without the shroud the fan would move much less air through the rad.

I agree, 1600 cfm seems a bit low, bigger better IMO (in most cases)

[55metalmonkey]

Don't know it it would fit since I don't have my rad and core support in yet but a pair of pusher fans might be an option
might be worth looking into

[samdjr74]

I was thinking about that too, there seems to be room between the radiator and the support for a couple of pushers.

So far I think I might go with this model

http://www.summitracing.com/parts/DER-16928/

Originally Posted by 55metalmonkey

Don't know it it would fit since I don't have my rad and core support in yet but a pair of pusher fans might be an option
might be worth looking into

[55metalmonkey]

4000 cfm sounds good but the 28.5" wide might be an issue. if it is in front of the core support it might just give you a good mounting surface. a little over 3" thick too, be worth diging out the tape measure and checking out

[samdjr74]

I just realized that as well, but I did find a single 16" pusher rated at 3600cfm's so that might be the ticket. But I need to remeasure the rad support to be sure.

If I run a single pusher fan with a built in shroud would I still need a shroud on the other side? I would think not right?

Originally Posted by 55metalmonkey

4000 cfm sounds good but the 28.5" wide might be an issue. if it is in front of the core support it might just give you a good mounting surface. a little over 3" thick too, be worth diging out the tape measure and checking out

[55metalmonkey]

Your right
you just need it on the side with the fan the other side should be as open as possible for air flow