The main problem with the oem fan is there is no shroud for it... that is huge in terms of cooling efficiency. the JTEC file does have control for 2 speeds but not sure if its possible to leverage it. Since I wont be towing with the dak, I think the low speed volvo fan mounted to a shroud will be fine. I may test the oem fan to see how much it draws for an apples to apples comparison against the volvo. Same fixture, same measurement locations etc...

 

Someone asked about this over on CumminsForum.... since I have the link in hand, posting it here for anyone interested...