Quote:
Originally Posted by DSSA
An interesting read on parasitic loss from mechanical fans:
Dyno testing on fans, alternators and oil.....all here!
A couple of issues to note if reading it:
1) The fan/clutch systems on the older Chevy Smallblock is going to be quite a bit larger/heavier than on the X5s.
2) Fan draw on a stationary dyno will differ than while driving (be larger) due to frontal flow in proportion to the speed you're traveling.
However, it gives a little insight on the subject with measured data.
I personally wouldn't remove my mechanical fan simply for the sake of performance gains on something like the X5, however, the other aspects like being able to have control over what temperature it starts/stops, being less of a PITA to work on the car, etc. is why I would switch it over like my E39 and Wrangler should the motivation/opportunity arise.
I wouldn't suggest it be a "go to" modification, but like all modifications to a car, whether it is worth it or not depends on your own desires/needs. |
Interesting document, good addition. More info--an electric fan runs at a constant CFM and other type fans do not. The same contribution to cooling is realized at an idle and max RPMs. That assumes the fan is running at all at higher RPMa when significant air is forced into the radiator. Because of the CFM at idle the fan shuts off some of the time. If racing the controller can be adjusted so that the electric doesn't run at all and for a short period of time the aux fan will not either.
Using a clutch fan as an example. It is always turning. Even when the radiator heat is not locking the thermal control the fan increases load as RPMs increase. The load is increased at all RPMs if the thermal control is locking which causes the clutch fan to move entirely based on engine RPMs.
FYI-I would like to add an electric water pump for the same benefits. I haven't looked but my bet is there is not one available.