Forced air intercooler fan

Installed a forced air fan on your 87-88 Turbo Coupe intercooler
By Jeff Korn  -  Technical Advisor, NATO

The stock intercooler on the 1987-88 Turbo Coupe is considered to be a well designed, efficient intercooler, but its location directly above the hot exhaust manifold and turbo leaves something to be desired.  When traveling at speed, the hood ducting does direct cool outside air over the intercooler, but when traveling at low speeds, the air flow over the intercooler is minimal, and the heat from the exhaust manifold and turbo actually heat the intake air, making the intercooler an “inter-heater”.  One solution to this problem is to switch to a front mount intercooler, such as a Volvo, Saab, Motorsport, etc. intercooler.  While this solution works quite well, considerable fabrication is required, a bypass valve will be needed due to the increased system volume, and turbo lag may be increased.  Another solution is to add a fan to the stock intercooler to constantly pull cool, outside air through the hood ducts and over the core.  I have added a puller fan to the stock intercooler on my 88 Turbo Coupe, and the fan significantly lowers the core temperature. For example, after slow city driving on an 80 degree day, I could burn my hand touching the intercooler core with the fan turned off, but with the fan turned on, the core stays cool enough to comfortably hold my hand on the core, even after “spirited driving”.  In 60 degree weather, the intercooler core stays cold. My “forced air intercooler”, in conjunction with my home built water injection system and T3 turbo, allows me to run 20 psi boost with 14 degrees initial timing even in 90 degree weather on 92 octane unleaded with no indication of the knock sensor pulling timing.

Note that I have upgraded my 88 Turbo Coupe to a water cooled T3 turbo, which required fabricating a custom set of water cooling lines for the T3.  When I fabricated these water lines, I made sure there would be clearance for the fan under the intercooler.  I suspect that the fan may not fit with the stock IHI turbo cooling lines in place, but fabricating new cooling lines using some metal tubing and high temperature hose should not be that difficult.  I also built an electronic controller to only turn on the fan when the air temperature in the outlet tank of the intercooler exceeds an adjustable set temperature, but a simple switch and relay can be used to manually control the fan.  I will discuss wiring the fan for manual on / off control.  If anyone has experience in electronics, and would like information on my solid state fan controller, contact me at [email protected] .

Materials needed:

-  A fan.  I used a Spal 6 ½” 330 CFM puller fan.  I bought it online from Racer Parts Wholesale www.racerpartswholesale.com for about $70.  This fan is made for high temperature environments, and is of very high quality.  This fan draws roughly six amps of electrical current.

-  Some way to mount the fan.  I used those plastic rod things used to mount transmission coolers to a radiator, along with high strength metal epoxy similar to JB weld.

-  Some thin sheet metal to form a baffle around the fan.

-  A 30 amp 12 Volt relay, a small SPST (single pole single throw) switch to turn the fan on and off, a two pole electrical connector so the fan power leads can easily be disconnected when removing the intercooler, several feet of 10 gauge wire and several feet of 16 gauge wire, and a 30 Amp fuse and fuse holder.

Mounting the fan to the intercooler:

       

There are many ways to do this, I suppose.  I used one of those plastic through the radiator tranny cooler mounting  kits available at any parts store. There are mounting holes on the fan that locate the plastic rods in the tranny cooler mounting kit right at the edges of the intercooler core.  I also used metal epoxy to seal the edges of the fan to the intercooler tanks for extra support.  Note the power wires in the split loom coming out of the fan with the two terminal electrical connector attached.  I drilled a small hole in the edge at the very back of intercooler  flange and used a tie wrap through the hole to secure the wire and keep it away from the turbo.  Also note the second wire coming out of the outlet tank, which is the temperature sensor for my fan controller, and note the bypass valve fitting on the inlet tank.  Note that a good way to attach the fan temporarily to the intercooler to test fit the assembly is to secure the fan to the intercooler with duct tape.

After the fan was mounted, I took some thin sheet metal and formed two shrouds to seal the intercooler tanks and sides to the fan.  There is about ½” to ¾” gap between the shrouds and the core to allow for air flow.  These shrouds are important, as they force all the air the fan pulls to go through the core.  I used high temperature RTV to attach the shrouds to the intercooler tanks, edges, and fan.  When done, I painted everything Ford dark blue (optional!).  Note that the fans structure is quite robust, and it looks to me as if some areas could be ground down somewhat for clearance if needed.

Electrical wiring:

I suggest wiring in a switch to be able to manually turn the fan on when needed. If you live in the northern US, the fan isn’t needed during cold weather, so a switch to turn it off would be a good idea, but if you live in the southern regions, you may want to wire it to stay on at all times. To wire it to stay on at all times, simply omit the switch from the circuit.  The switch can be located under the hood, or on the dash. It is a good idea to locate the fuse as close as possible to the battery terminal of the starter solenoid. If the switch is located on the dash, locate a wire under the dash that is hot in run, such as the power feed to the regular / premium fuel switch (red / yellow wire).  If the switch is located under the hood, a good wire to tap into is the red wire going to pin 24 of the integrated controller. Be sure to solder all connections and splices.