[ecoTruck]

So I have been thinking about converting to an electric fan to try and save some fuel. The mechanical fan seems to pull a lot of air even when the truck is cold/fan clutch is disengaged. I have never noticed the fan cutting in except for when towing or climbing big hills during the summer, so the electric fan would not have to run very often.

I wanted to test how much drag the mechanical fan actually puts on the engine and was hoping someone could verify that my test makes sense...

I plugged in my code reader which has a live data feature that can display Load %.

With the mechanical fan still in place I drove a loop and recorded the Load % value on a flat stretch of road at 60 km/h to be a 10.5%, and on a long hill at 50km/h the load read 25.0%.

Then I removed the mechanical fan and drove along the same route, and on the same flat section of road the Load was a steady 9.0% and on the same hill as before it was 22.0%.
The temp gage stayed between 80-90 Celsius during both tests.

So thats a 14% reduction in load on the flat, and a 12% reduction on the hill?? It surprises me much load could be from the fan alone. From my test results I think I'm going to go ahead with an e-fan, it seems like I should see some noticeable fuel economy gains, should be close to a 4% increase in mpg if you figure the engine converts 1/3 of the fuel to mechanical energy (as long as my math is correct and 1/3 may be a bit optimistic I'm not sure).

I have heard that if you take the fan off your water pump can wear out quicker as it is used to having the fan pull on the shaft/bearings, I've also heard that it will last longer because you don't have the fan hanging off of it? If anyone has done an e-fan conversion please let me know if you've had or heard of any water pump issues.