Joff and MrsJoff's Chaste White BorgWarner FD build

[joff]

Originally Posted by RCCAZ 1

Very nice! What's the purpose of the angle iron that separates the fans and the short pieces on the outside edges of the fans? Do they have a high/low fan speed like to stockers and will they operate off of the stock fan relays?

Thanks!

The sheet aluminum is very thin and won't support the fans weight. The angle pieces down the middle hold the nutserts for the fan mount point in the center. The other 3 of 4 mounts are around the perimeter in the aluminum tube frame. The short pieces in the corners are further reinforcement for the frame which I probably didn't need, but had extra material handy. I like using the "L" angle material since it is so much more stiff than regular aluminum straps for a given weight.

The fans are not two speed, which simplifies the wiring enough to allow me to simply get rid of the fan relays and the old sagging ugly rubber fan relay mounting that doesn't seem to age well. I'm going to use a big simple single relay and some simple electronics with a radiator fin temperature probe to turn on the fans.

I like the idea of switching the radiator fans based on a sensor more relevant to the radiator temperature rather than engine temperature. I can set the activation temperature to somewhere much lower than the coolant thermostat (and therefore at a lower temp than the engine wants to steady-state at) and still not have to worry about having the fans on 100% since the fan will be activated only when there is significant hot coolant flow through the radiator. This radiator is a 4-pass radiator so I should be able to play games with probe location to adjust hysteresis and whether I'm monitoring radiator inlet or outlet temperature easily too.