spdcrazy Posted July 12, 2016 Report Share Posted July 12, 2016 I'm not here to discuss if I should, how I should or anything at this time. However, I was searching around and found a huge jump in CFM ratings on the perma cool fans verse all the other brands. Perma-cool standard fans from 7-12in diameter are rated around 2400CFM. I understand CFM rating vary depending on the static pressure (I.E. the radiator, AC condenser, etc). I have an email out to perma cool now, but I expect their numbers are at ZERO static pressure? even still, this is a very high number when compared to most, even the extreme performance line of SPAL fans don't quite reach this. Any thoughts? price wise they are reasonable as well! 1 Quote Link to comment
datzenmike Posted July 12, 2016 Report Share Posted July 12, 2016 When driving they shouldn't even be on, so this leaves low speed and idling in traffic. Engines don't usually make much power and heat when idling and rolling around town so you don't need huge CFM rating. The exception is climbing steep hills (in town or at slow speeds) or being stuck in mud and snow. Not really that common occurrence. Take a look at some of the vehicles out there in wrecking yards and how small the fans and blades are. I had a 9" pusher fan from a Volvo? on the front of my 620 but never got around to wiring in a sensor. Drove it around with it off and only once or twice got out in traffic and connected it to cool it down. Gauge dropped immediately or withing half a block if you were driving. To be on the safe side get the largest that will fit, or you can afford ... for peace of mind. 2 Quote Link to comment
spdcrazy Posted July 13, 2016 Author Report Share Posted July 13, 2016 I have read a lot on the idea, and I agree. what i'm curious about is WHY and HOW they can claim so much. much more than I need, but my curiousity is up. 1 Quote Link to comment
datzenmike Posted July 13, 2016 Report Share Posted July 13, 2016 I'm looking to put a fan on my 710 in the near future. I noticed long ago that when starting off cold there is quite a roaring noise from the fan but in about half a block it reduces and goes away. While working on my carb recently I was under the hood on start up and witnessed this first hand. The fan slowed down as it got quieter while the engine was just idling. I reached over and let my fingers brush against the spinning blades and easily stopped them! I guess the clutch is not working or working properly. It never has over heated under any condition of driving including a 20 min up hill in 3rd mountain climb at full throttle. Again another proof that a fan is not necessary if the vehicle is moving forward fast enough. I have air con (that does not work) so there is a condenser? in front of it. The plan is to remove this. I picked up an electric pusher fan from a VG33 Xterra that looks like it will fit close enough. It isn't huge but good enough for 3.3 liters... got to be over kill. The sensor is a lower rad hose in-line from an '89? 240sx. I have a spare water pump that I will cut the clutch off or will just remove the fan blades from this one. 1 Quote Link to comment
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