The Stovebolt Site Forums The Shop Area The HiPo Shop Radiator to shroud clearance?

In my '46 Panel I've got a 350 sbc and a 4 core alminum radiator with a 2750 cfm 17" electric fan. It is mounted by three brackets that I made but I want to put an alminum shroud around it. With the brackets the fan is mounted almost tight to the radiator and I need to pull it back alittle when I mount it to the shroud to get better air flow. As close as I can figure I can only move the fan back 1/2" from the radiator any more and I get to close to the water pump pully. Will this be enough clearance to get the full air flow effect of the shroud?

First off, your 2750 cfm electric fan will not move 2750 cfm thru a radiator, much less a 4-core aluminum radiator. The rating advertized is at 0" static. Your radiator will have about 1.8-2.2" of static pressure drop (assuming a 12FPI pitch). Depending on the brand of fan you are running, that will put you into about 1800-2200 CFM thru the radiator. The shroud you mentioned will make the most use of the air and ensures it moves thru the radiator. However with only a 1/2" off the core, you will not be utilizing the whole radiator. The best rule of thumb that exists is 1/2 the fan hub distance away minimum. This minimized the "air doughnut" effect. However if you have obstacles, you will need to compromise. If you move the fan off center a bit, can you get farther away?

Thanks Scott, The radiator is already moved forward 3/4", the fan is a Spal S blade and the thinest I could find at 4 1/4". I only have 4 3/4" from the water pump pulley to the radiator. The fan motor is clear of the pulley by about 1" because it is mounted high center, the fan does cover completely side to side. It has been working fine for two years now and I just want to clean the appearance up. What I want to do is build the shroud and mount the fan to it. Moving the fan back I know I need to draw more of the air from the bottom up thru the fan thats why I'm concerned about the distance. The most space I can get from radiator to shroud is 3/4" and that puts the fan motor 1/2" from the pulley. A little close for me and why I'm not sure if its enough.

I congratulate you on the Spal. Spal and Tri-Pac are the only two electric fans that work, and they publish fan curves. I have run an electric fan close enough to the water pump to run flat-head screws in the past. The engine movement is primarily side-to-side and not much movement fore/aft, so if you have 1/2", I would use up about 3/8" of it.

You could also run a pair of 12" pushers