Does running the two 97+ fans put strain on the stock alternator to the point of the alternator creating extra drag?
Thanks for your help.
The answer is yes. Running two stock fans consume a ton of power. I ran a stock aux fan plus a Ford two speed until I replaced it all with the Flex-a-lite aluminium set up which has three fans.
What I did to accommodate the two fan set up was to install a
new 200 Amp Alternator. Some where in here is the part number. Hate to say search for it though... In that setup, the Ford ran on low with the ignition and shifted to high when fan was called by either the PCM or the water pump controller.
On average, the parasitic drag created by the alternator is preferable to the drag from the mechanical fan as it is less.
The stock fan has a 40A fuse as did each leg of the Ford fan. These are required to absorb the inrush current at start up. Once running, they both do draw less.
The fans I am running now are fused at 10A each. Control wise, I dumped the controller provided by Flex-a-lite and had the passenger side running full time with the ignition and the center/driver side fans operating by command of either the PCM or my electric water pump controller via simple relay logic.
Here is the logic behind running the passenger side full time. I have observed on two separate XJs the A/C compressor "short cycling" when there is not a fan running to cool the condenser coil. Mayhap this is a coincident. But, two Heeps with identical issues with the A/C both solved by running a fan makes me wonder...