INSTALLING
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 jkorn@voyager.net
.
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.
