Process West's goal when developing
this top mounted intercooler was to make it the very best aftermarket
top mounted intercooler for WRX/STi... period. They studied
their competitors products and fixed all of the mistakes they have
made...some of them major.
The most obvious error that
EVERY competitor makes
is not supplying their intercooler with proper ducting/shrouding
to
suit the increased size of the new intercooler. There is no
point in installing a larger intercooler and leaving the factory
under
bonnet splitter/scroud in place. Therefore, a properly
sized splitter/shroud is included to suit the application.
The next major problem that
competitors have (and they all copy each other) is building
an intercooler that is too
thick. Their design criteria is spot on for bragging rights
and marketing.
They say that bigger is better. This is totally not the case
with
an intercooler that is mounted at 90 degrees to the ambient
air flow.
For good heat exchange to take place you need good ambient airflow
through the intercooler. In the case of the boxer engine with its
intercooler mounted under a bonnet scoop the ambient airflow speed
is already struggling after doing a 90 degree turn through the
scoop. The last thing it now needs to do is find its way through
114mm
(4.5in) of intercooler core. This will result poor heat exchange
and high inlet temps. This intercooler is 90mm thick (3.5in) and in turn the intercooler
breathes, gives lower outlets temps and in turn more power.
Turbo compessor
outlet to intercooler (Y-pipe) design
Almost all of the aftermarket y-pipes we see do not distribute
the charge air flow along the intercooler evenly. Their
y-pipe usually consists of one nicely flowing section with an
afterthought
spout as the second duct.
Considering all 3 features, this top mounted intercooler gives the perfectly designed top mounted
intercooler for Subaru.
Dynos
and top mounted intercoolers are not a great mix. No
matter where
you position
the dyno fan there is still very little air flow into
the bonnet scoop. Having said that both the stock intercooler
and the
PW upgrade intercooler were subject to exactly the same
test conditions. A few other things worth mentioning. The test vehicle was a stock
(apart from a BPM GT exhaust system) 05 WRX. Stock WRXs consistently
put down about 90kw ATW on his dyno. The intercooler outlet temp
probe was placed in the silicon hose joiner at the throttle body.
Process West started off with the PW intercooler/splitter and did a base
line power run. Result was 115.5kw. Looking at the intercooler
outlet temp saw a peak of 51C. Next they installed the stock intercooler/splitter. Max power was
107.5kw.
Process West had some even more amazing road test results with the
PW intercooler/splitter combo, they were unable to get
the intercooler outlet temp above
43C no matter how hard the car was pushed. With the factory intercooler/splitter under the same hard driving, the intercooler outlet temp saw a peak of 72C which
showed no signs of stopping.
