I have a mechanical puller on my 38 Chevy, but no shroud. Just not enough room to make a good shroud with the big block in there, and I already have the radiator mounted about 4 inches forward of stock. I have an elec pusher on the front that really makes a difference. When stuck in traffic, I can flip on the pusher and keep it at 230 or less, even hot days. Once running down the road at 30 mph or better, the elec is turned off and I run around 180-200 max. I think many of our hot rods have the same basic problem, it is not the radiator capacity, it is one of too low of airflow through the radiator at slow speeds or stopped in traffic. My elec is on a manual switch so I just turn it on when needed. I definitely do need the extra airflow help from the elec pusher at times.
I already posted an explanation. I like helping people, but why would I invest the time and effort to write a tutorial for you? I suggest you do some legitimate research and then decide for yourself what's right.
About that picture. Maybe he had cooling or fan trouble on the way to that show and that was the best fix to get home. Just saying.
That makes more sense. I figured there was a joke that I was missing, sometimes the funniest shit in the world just flies right over my head.
I never said puller fans won't work. That wasn't the question. Based on your response I'm guessing you won't be at the library tomorrow looking for a physics book? Seriously, not trying to be a wise-ass, you should check it out for yourself. Not doing that leaves you relying on what others say, and on intuitions that aren't always reliable.
Mines a puller. Cooloing components with shroud. Never had any heat issues on my recent trip to Nats South. 48 Poncho
yea jeff, and only 10-30 hp loss from the fan depending on when its locked or now I say electric. stock fan from junkyard: ford taurus fan- two speed and AMAZING flow. Volvo's use the same style fan as well...... aftemarket- SPAL fans fully kick ass. get the one that fits best, and be happy. they move incredible amounts of air as well. I have a puller (main) run off the fuel injection computer, and a pusher from a thermo switch and a/c request.
I think the pusher is less efficient when going down the road, because the incoming air is "pinwheeled" away and doesn't go through the radiator core. Either a pusher or puller that's sized properly for your custom situation should cool properly when the vehicle is stopped. I have zero room for a mechanical fan so I have a 16" SPAL puller with curved blades that works perfectly.
Hmmmmmm.... Would that be in the same physics reference book that proclaims that it is impossible for bumblebees to fly (based on a law of physics), yet they somehow find a way? Wouldn't you consider that counter-intuitive, as well? Not trying to be wise-ass either, I think you and I will agree that we simply disagree...
I thought of something. Not related to pusher or puller. Just make sure that your fan does not make more noise than your car!! I can't stand when some sanitized street rod drives by and I hear the elec fan over the engine.
I agree, doesn't sound cool. However, it may be preferable to the sound of steam escaping from the radiator cap.
Another opinion: The effectiveness of a pusher vs a puller can be debated but here are the considerations. Fan theory tells us that for a STATIONARY system the fan should be mounted in the most dense air, ie, lowest temperature air. If we have a hot radiator, fan theory says to put it in front and push. If we have an evaporator, put it behind and pull. HOWEVER, a fan is moving air...air is a fluid. The fan has zero idea of where the air is going so if we mount a fan in either front or back without a fan shroud to guide the air, the air will take the path of least resistance. That means that the air may spill around the radiator, out the bottom of the grille, etc. So, the auto engineers design a nice shroud.....but when they design a shroud for the front of the radiator, a big problem occurs....when the car is moving, the natural air flow outweighs the fan air flow so you want the fan and shroud to disappear. The fan can freewheel but the shroud is a big impediment to air flow.....so no shroud makes a pusher fan suck. It must be true, I saw it on the internet. mike
so you do what BMW does, and have about 10 "flapper" set ups to make the shroud work like a shroud when its sitting, but airflow at 70 pushes the little "flappers" open- making it dissapear OR even thermally control them like some BMW's........
just my .02 but had put a stock 302 in a 97 ranger put the fan on as a pusher and would overheat pretty fast. swapped it to the back as a puller and did not have a shroud on either way and never got above 190 as a puller. It worked for me but every setup and fan is different....
When I added A/C to our 39 I put a Spal puller up high on the radiator. It wasn't as great a CFM as I would have liked cause of space constraints so I put a smaller pusher low in front on the condenser. The two were not in opposition to each other. Puller ran off temperature switch and the pusher ran off of the A/C trinary switch. Each also had manual override. No problems with A/C running in 90 degree weather.
Another factor that comes into consideration (though I have no idea how great its effect is) is that we are looking for airflow for the sake of cooling, and that the pressure of the air at the point where it is doing the cooling might play a role. Lower the pressure of air and it wants either to contract or to absorb more heat to restore equilibrium, and vice versa. That would seem to argue for lowering the air pressure in the core, as a puller set-up would achieve. Could it be that the effect of this is just sufficient to offset the difference in fan efficiency plus a bit more, to tilt the balance in favour of a puller?
Folks I have known have added a pusher as an auxiliary fan. I'm running a single 17" or 16" electric puller and it gets the job done.
As it applies to this situation I think this all would be more in the realm of theoretical rather than significant, but yes, increasing air pressure causes heating. Lowering pressure causes cooling. Another factor to ponder; the denser the air, the better it transfers/conducts heat.
Here is what I build for a space deficient 30 A truck. Fixed it right up...... Oh and it is a Spal puller on a shroud with a Mezier 55 GPH electric remote pump. This was out of necessity rather then the Rube Goldberg effect. The dump flaps worked well too. Sucked in to the opening at low speed and blew open at road speeds.
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