I use SPAL dual fan with shroud. They have high CFM, and the shroud fits almost 100% on the core of the radiator with no "leakage", so all flow is pulled through the core, and not from the side. Has rubber "flaps" (along top and bottom of shroud) for outflow at highway speeds. Higher amps is required for higher CFM and allows the blades to pull under all conditions. (amps are to fans as torque is to moving weight, amps/torque wins) https://www.summitracing.com/parts/spu-ix-30102130 (I got them from another vendor a while back, for $289. But they have gone up!) Coverage of core, proper shroud fit, amps/CFM, and pulling, not pushing are key to fans optimal work. Pulling is 100% through the core that is enshrouded, then most pressure at higher vehicle speeds will "bleed" past the fan blades and/or the flaps. Pushing will build up pressure and can result in impeded airflow through the core as the air pressure in front of the fans that are in front of the radiator can deflect airflow away from the core and the fans components also block airflow, creating very "dirty" airflow. (I have seen "pusher" fans, create overheating at highway speeds on cars with and without mechanical blades) But, good radiator, and cooling system health is a must for fans to be most effective. Correct amp alternator, wire gauge to handle the loads and proper grounding/bonding/connections, good correct stat, and battery are a must.
Seen 3 different test over the past 20 years. The worst fans are flex fixed and stock fixed. The best are stock type heavy duty thermostat clutch, not the thick truck style, and 5, 6, 7 blade fans. Viscous style clutches are cheaper but never really release like a thermostatic coil wound type. Average about 9 or 10 hp more drag than electric when tested stationary and probably nothing while driving.
This is going in the right place. Nice. OK, I bought a aluminum generic fan housing for a single fan. It has the rubber flaps in it also. I was leaning toward using a 2 speed Ford Taurus fan. 2500cfm on low and 4000+cfm on high. I was going to modify the Taurus fan housing to fit the opening in the aluminum piece. You can use the 2-speed Taurus fan, along with a Volvo 2-speed fan relay controller (#9442933 or #1398845), finishing with a BMW dual temp switch (#61311378073 for 195F/210F or #61318361787 for 176F/190F). This is going to be my plan. This setup spikes at 60amps then drops 25amps. Going to mount the temp sensor in the front coolant pass of my B4B.
I’ve run a Taurus fan in my Jeep with a TBI 350 for the past 18 years. My ‘72 Skylark came to me with a Ford Escape dual fan setup. I plan to use the Volvo/BMW setup on my Buick. I’m an electric fan convert. I think for a slow speed Jeep the Taurus fan is ideal, we’ll see how I like the Ford item on my “cruiser” 455. I’m not sure how it’ll turn out
Sounds cool but make sure you wire the dual fans so they both go on in the secondary mode. The Volvo relay drops the primary power when the the thermostatic switch goes to the higher setting. If you wire it one fan to a lead, the low temp primary fan will shut down and only the secondary fan will run. It will take a additional relay to make that happen. I thought that out and I decided on the single 2 speed fan set up. I like Rube Goldburg setup's but I wanted to keep this really simple.
I hope it is cool but it's free.99 and we'll see how it works. Good advice on keeping both fans going on high. For right now, I think they are both on all the time? Simple is preferred as I'm a simple minded type of guy when possible. People in the Jeep world have moved on from the Taurus fans to a Volvo unit or the Mark VIII fan. I'm not sure how much physically bigger the shroud is on the Mark VIII unit but it does have more airflow. For a big block, I think a shroud is pretty critical but I haven't played with trying to keep a big block cool for at least 30 years. I'll be learning as I go. I honestly wouldn't be surprised if I'm cussing at the electrics and trying to dig up a stock 455 shroud/fan setup this summer?
I'm old school....I run a single Fiero fan on a toggle and control it manually. Leave off then on when warmed up in hot weather, most of time leave it off. Stuck in traffic leave it on. I have a nice blue indicator light that I can see out of corner of my eye so I know when it's on. Key is to have a good aluminum radiator in first place.....
