10 - 12 blade 12" Slimline fans are lighter and thinner, pull significantly more air through than stock Porsche radiator fans, and use much less electricity.
Right now I run the early 3 blade OEM fans and they just do enough to keep the car cool (Plus I've had to replace both fans already - they do burn out being 20 years old). For reliability purposes I would recommend we allow aftermarket slim fans that can mount directly to the radiator. There wouldn't be any performance affect outside of some weight reduction from the heavy factory unit and mounts.
The aftermarket fans run $20 new and are found everywhere. They mount directly to the radiator itself making them very easy to install and provide much better cooling by pulling more CFM through using less power. They can run off the current relay setup or you can hardwire them in - or even get a custom unit to turn on the fans at a specific temperature.
Here's a link to eBay - $20 for fan with all mounting hardware. Pretty cheap, yet I think it is effective in giving our cars a little more cooling capacity (especially those with the internal bath oil coolers).
If I were going to replace my fans, I'd want to replace them with something that moves a lot of air. The ones you linked to on eBay on move 1,250 CFM. They're a great deal at $20, but I'd rather spend a little more and get something like this that can move almost twice as much air.
Fans!!!! why are you running fans? Take 15 lbs off the front of the car and get rid of them.
No need for them to be there.
No new rules IMO.
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