when I saw the post I was going to mention ask JoeG but he has already got there. It looks like there was a bad run of them I don't know if the problem is fixed but there may still be some bad ones floating around.
Jim, why the desire for more cooling? Have you made drastic changes to the engine? In most cases the factory set ups when complete and installed correctly work the best. I know before you all say why do I think this, we must all remember that the manufactures spend hundreds, thousands and millions on developing parts, assemblies and cars. If all is correct,then making sure all the parts of the cooling system are in good working order,then the car should cool to stanards set forth when it was engineered. Wow until now I would have thought, flex fan, but hey we all get older, or is it wiser?
I say someone at the local performance shop with a sec. gen. one of the blades came off and put a gash/crack in his custom fiberglass hood/radiator. Ever since then i scrapped mine and got a clutch. Also flex fans cool worse,not better. They are supposed to be better for hp, they suck at cooling
My dad bought a brand new Perma Cool flex fan a few years ago for his 1959 Apache w/ a big block. Anyways, the blades over flexed and and tore his radiator to shreds. He wasn't on it or anything, just driving normal up a hill and then he heard a lound horrible noise pulled over and you know the rest of the story. I have one on my El Camino, but I have been meaning to change it for some time since this happened to my dad. It's just not worth the chance.
Ditto on the clutch fans. These things belong in the trash. I had one not release and they don't take to high rpm very well. Shaft seperated and went through my 4 core radiator, spared my original cowl hood thank goodness. Nothing but electric fans for me after that.
I have done quite abit of research on flex fans over the last three years with differing cooling articles that I write for web sites and magazines and this subject becoming inclusive to the topic.
It used to be that flex fans where cheap, poorly made and poor cooling devices that could eat your hood in a hurray. I was a anti-flex fan zelot for alot of years.....until now under the right conditions.
Recently as just last year, Derale products (www.derale.com) has come out with a newer technology of flex fans that cool much better at idle and slow speeds...in fact the very same as a fixed bladed fan of comprobable size, and take up less hp up top. The blades are made from higher strength stainless steel as well are attached with differing design and technology. They are good for 10K Rpms (we have spun them up on an electric system to 16K...no problem) and come with cool chrome hubs to boot. What got me started on trying a flex fan was that one of the engineers from Derale last year (00) at SEMA gave me one to try on my Camaro after an engineering discussion on this very subject. It is not only beautiful...but cools in the harshest conditions and takes the gear pounding 7500RPM shift points with ease. And..on top of that, it is so efficient that I can't hear it turning at high speeds like all the others that I have seen...meaning efficient design up high with little load. The main ingredient here is the stainless steel has been shifted to a stronger metal alloy, allowing for stiffer blades at lower rpms and a more useful dynamic loading of the blades as the rpm increases. This means the blades don't load up like the older models. The attachment method on these is completely differing as well, but still uses a higher grade and more mounting point compression rivets with front edge support down almost the entire leading edge.
Needless to say...I am impressed and they are not cheap, but very reliable so far. I will run it until next summer when I will remove and xray for cracks. I am betting that it will be as good as new.
However, like one poster suggested...I like electric fans too....they simply can't be beat for cooling where it's needed and reliable too.
STEVE JACK ConceptOne Pulleys and Brackets
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