Thread: Intercooler fans.

I have had a intercooled m90 setup for a while now. Been happy with it other then it heat soaking horribly at the drag strip / in traffic. What I noticed is that the heat exchanger up front would get to 140+ degrees on 80 degree days. This obviously hurt the performance of the intercooler and would cause inconsistancy all the time depending on how heat soaked it was. The interstate was never a problem because there was plenty of airflow. After doing a bit more research I found that people consistently saw a huge improvement by adding fans to the heat exchanger. I agreed because commanding my regular engine fans on high would help considerably. So I did the only logical thing and added them!

My personal requirements.

1. Cant run non stop. It wastes energy and is annoying. Also kills the fans faster.
2. Must be able to run automatically when necessary.
3. Must be able to turn them and the pump on manually to keep the core at ambient temps even with a 212 degree engine heat soaking while the car is turned off in the staging lanes.

Unfortunately nobody makes a affordable intercooler fan controller that I could find at least (And regular radiator fan controllers typically cannot be set lower than 160*) so I opted to trigger my fan relay off of the cars stock cooling fans. This actually works quite well because the fans only run when its A. Really hot outside and B. When im not moving. Sure they also run non stop with the air conditioner but honestly 95% of the time the ac is running its hot enough outside for the cooling fans to need to run anyways.

So I drew up a crude schematic of how to have my auto fans and always running pump along with a manual switch for when im playing racecar.



Then I installed some freakin cool 6.5" fans that are only 2" thick!



Tapped into the stock fan wiring by removing a bit of insulation, twisting, and soldering.



And then wired it all up. It works perfect! Currently its winter so its hard to test in the 10* weather but after idling for 20 minutes the heat exchanger was 40* above ambient. When I plugged the relay back in for my new fans it returned back to ambient automatically with the cars cooling fans cycling... or at least close enough that my temp probe couldn't tell. Im freakin excited to test it out at the dragstrip!

thats pretty cool.

if i get a ic i plan to run a vw rad, then put a 16 inch fan on it and wire it like fog lights, relay on the fan and a on off switch, why not let it run full time? the cooler the better.

i did a dual 16 inch fan install on my last truck. ( took the clutch fan off) relay to each fan set up that way ^^^, volts didnt even drop that i could notice. truck ran a line cooler too.

They are loud, it costs fuel to run the alternator that runs them, its another 15 amps worth of draw on my already heavily taxed electrical system, completely pointless during 95% of winter.

how does it cost more fuel to turn the alt? its already turning.

The law of conservation of energy comes into effect here. When there is zero load on the alternator you only have to overcome the friction in its bearings and whatever it takes to spin its little cooling fan which is very little. When you put a load on it it takes energy to overcome the magnetic fields and keep it spinning. 1 horsepower is ~750 watts of energy. The alternator is far from 100% efficient though so your actually putting about 1hp of load on the engine for every 500 watts your drawing from the alternator. At full load that means a 120 amp alternator pulls 3-5 horsepower. That's also why your engine rpm will dip a bit when you turn on a heavy load like the cooling fans or rear defrost.

ok, i see what your saying. id still not care one bit. 1 hp your not gonna feel, or miss, i'll bet the engine makes more power if the ic is even cooler and that would justify it and be a plus over all.

and you can always add a sticker to make up the HP loss lol

Im not going to make it colder then ambiant no matter what I do. So if the car is moving and getting plenty of airflow to keep the intercooler loop at ambient I wont gain anything except a loss of fuel economy. Not to mention the fact that there is no way these fans are going to push more air then when the car is going 30mph or faster so again... complete waste to have them running all the time. There is a reason you don't see any factory cars with fans running non stop.

ambient temps get hot. and why id have a on/off switch. why let the engine temps control them? unless you tuned one fan to come on at a much lower temp and ran the ic fans off that signal. i like that idea already.

what you did will work, not saying it wont.

Hard to tell in your schematic, but do you have the cooling fans on their own relays?

Another idea would be to install a thermostat into the HE that would trigger the relays as well, so they only turn on when the HE is actually hot enough to require them. You can also use it to change the temperature you want the fans to turn on:

I have it controlling 2 Taurus e-fans on my truck.

Unfortunately I have yet to find a electronic fan controller that will let me set it below 160*. I have considered adding a parallel resistor to trick the sensor. As for right now I am happy. It is triggering when the car is being abused or idling just like I want it to. I still can turn the pump and fans on by hand as well.