Aren’t they the same fan motor? I thought just the blade design and shroud was different.
Either way, I’ve made a semi-simple electronic circuit that uses a 1992 Sentra rad fan switch and a 1987 Z31 a/c condensor fan switch and I have the two stage taurus e-fan running on my z31, and for the 500km that I’ve been beating on the vg33et (0 psi for break in), I’ve never seen the temp on my new racing rad go over the half way mark on the gauge. and the oil temp is rock solid at the middle.
if you can keep the water at the proper temp for most of the time the oil will have a tendency to stay cooler and might negate the effects of needing to plumb oil cooler lines, to even further inhibit air to the radiator by putting it infront of the FMIC (if that’s where s13 ppl put them?).
I think the taurus fan pushes something like 2500cfm on low and 4000cfm on high, and my circuit makes the low speed turn on at 189 and off at 182 F, and the high speed turns on at 212 and off at 200 F. I did this with two sensors and two 70 amp relays, and it’s been good for 2 weeks now.
I’ve never seen it go to high speed.
My advice would be to try and duct as much air and seal off gaps at the front of the car leading to the rad, and use aluminum tape temporarily in small places that air will go through to see if it helps, then build something better once you’ve solved the issue. And upgrade to the Taurus or the Mark VII fan if it’s better. I know the Taurus one will suck the leaves off the pavement on low and stick them to your rad (which is why I put black windscreen infront too, to protect my 500 dollar custom rad from rocks and stop leaves from getting in behind my bumpers and rad.
Also try and run a bit more water in your mix (the coolant won’t do much in the weather we’re having lately) 30 % coolant in this temperature as of late is fine and will extract more heat per volume of fluid pumped.
The FMIC may not be the problem, I think it’s the air going around the rad rather than through it. seal it up.