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Old 05-20-2021, 08:26 PM   #45 (permalink)
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Originally Posted by Isaac Zachary View Post
I've noticed cooling fans playing an effect going up a steep mountain pass at highway speeds, at lest at speeds up to 45mph. I couldn't really go much faster in my Golf diesel, the last car I had the fan go out while driving up a mountain pass. I kept going, it was about 50-60F outside, and the needle got a bit too close for comfort to the red line by the time I got to the top of the pass.

When the fan got covered by loose firewall material on the Super Beetle going up a hill at 65mph that made for a quick engine failure.
Thanks for sharing. I never would have thought a fan failure would make such a difference going 45 MPH, especially on such a cool day. Everything I could find says that electric radiator fans are typically outflowed by ram air at speeds of over somewhere between 20 and 40 MPH, although obviously this would depend on the design of the vehicle and how powerful the fans are, so the only way to know for sure is to test it.

I think one of the biggest factor is how well the radiator is ducted in. A radiator with large gaps around it that allow a significant amount of ram air to go over or around the rad rather than through it like how my car came would surely rely a bit more on the fans than a vehicle with a radiator that's properly ducted to the grill so all air is forced through the rad and can not bypass it like how my radiator is now. Ever since I ducted my radiator, I noticed that the fans don't seem to run as much in traffic.
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