Pullers are generally more efficient then pushers, but not always. It is a function of the air pressure drop across the fan, blade design, fan RPM, and fan motor power. Also, don't just look at the CFM rating on the box. That rating is worthless without knowing the pressure drop that the CFM rating occurs at. You need to look at the entire fan curve in order to understand the true performance of a fan. Don't buy a fan from a company that doesn't provide the entire fan curve. Below is a chart from Spal of their common 16" suction fans. As can seen, the performance varies widely, but at some point all of them are capable of moving 885 cfm (1500 m^3/h). The pressure drop is going to be a function of the fan shroud design, fin pitch of the radiator, core thickness, and number of coolers that are in front of the fan. Thicker cores, additional coolers (oil, AC condenser, charge cooler, etc) and denser fin pitches all cause the pressure drop to increase and the fan performance to decrease.
I live in one of the hottest most humid climates here in Jacksonville Florida, pusher fans work great for me. Here in the "big city" it might be 97 degrees and 90 % humidity, you will get stuck in stop and go traffic a lot so you damn well better have a good cooling system. Electric fans are ugly so I use pushers, I can hide them behind the grill.
The air, as it passes through the core, gets hotter and therefore gets a lot 'bigger' [sorry to act like a smarty because everyone knows that; but I had to point it out anyway] . The engine side of the core is therefore the 'problem' side: A lot more volume of air must squeeze between the tubes. A pusher is too far away from the problem to have any real effect. The puller is in position to contend with the most restricted area. Summit, Jegs, et al, all say the puller position is 'recommended'. Generally a vendor, not wishing to miss any sales, is rather loath to say "Don't do it" in plane language. Not to say that lots of folks have not had success with a pusher. I think a guy should go ahead and do it as long as he doesn't care if he might be setting a landmine for himself somewhere down the line. Nothing, of course, beats a engine mounted fan.
I agree,if you have room for a mechanical fan use a steel bladed fan not a cheap aluminum flex fan. This fan will suck a golf ball through 50 foo!t of garden hose! HRP
I use two cheap no-name $30.00 10" fans on each car, I bought them at the Daytona swap meet. I stack them behind the 32 grill they fit perfectly, I placed the Chevy II fans diagonally. All three are non-stock V-8s. Some guys say you need this or you need that or it won't cool or block air flow, maybe for them, but my mine cool just fine, I like to keep things simple. Use what works for you. Zoom in on the pick and you can see them.
Because they are much better controlled. Most guys have a toggle switch it at best a temp sensor. Modern stuff has a lot of fan capacity and they are computer controller. Multiple fans and multiple speeds. Sometimes PWM. Trans temp and ac high side pressures all have an affect on how the fans behave. Some chryslers actually run the fan at certain cold temps to blow off condensation from the rad. Modern stuff doesn't depend on airflow at all. A lot more engineering there.
Plus modern stuff easily runs up to 230. AC performance a bigger concern than keeping temps below 195.
on this 32 Ford radiator I used in my Jaguar I used two 10" fans to avoid the water pump. $20 each from Skip White Performance
That's why the zip's riser was designed,it moves the water pump up 5" to center the fan on the radiator.HRP This is the late Deuce Roadsters 3 window,notice how high the fan is? HRP
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