Ever wondered how an aftermarket intercooler is made? What
separates quality intercooler construction from lesser jobs? We went along to
APS (Air Power Systems) to see how Australia's largest aftermarket tuning house
does it!
The APS Intercooler Manufacturing Process...
This photo shows the core that is used in the APS DR 500
front-mount intercooler kit for GD-series Subaru WRXs/STis. The specifications
of the core are nominated by APS - heat transfer area, fin dimensions and
spacing, thermal conductivity and other variables are all considered in the
selection of the core. Note that the same core specifications are rarely used in
more than one application.
With the intercooler core supplied from an outside manufacturer,
the next step is to attach the end-tanks. APS uses a jig to ensure accuracy
during this process. As seen here, the end-tanks are initially heated on a hot
plate, which improves the welding.
End-tanks are first tacked to each corner of the core before the
seams are fully TIG welded. The intercooler mounting bracket and tabs are also
welded on at this stage - APS use sturdy 10mm thick aluminium mounting tabs on
the DR-series intercooler.
Cast aluminium end-tanks are used in the majority of
APS intercooler kits. These tanks are extremely lightweight and feature very
smooth internals to ensure maximum charge-air flow. Note that the hose fitting
incorporates an all-important raised bead around its outer perimeter - this
reduces the chance of intercooler hoses blowing off at high boost pressure.
One welded, the intercooler assembly is pressure-tested in a bath of water. One
end-tank fitting is sealed with a rubber bung and the opposite end is connected
to a regulated compressed air supply. Test pressure is generally
around 10 psi. The pressurised intercooler is immersed in a tank of water
and any leaks are identified as bubbles. If any bubbles are detected,
the intercooler is returned to the welding bench for repair.
After being pressure-tested, the intercooler is placed in a large
cleaner/dryer machine. Inside, cleaning chemicals
are sprayed onto the intercooler to remove the grease and grime and that
inevitably builds up on the outside of the unit during storage and handling.
Note that end-tank fittings are sealed to prevent chemicals puddling inside the
core.
After cleaning, the machine then goes into a hot air drying
cycle. In total, the process takes about 2 minutes.
The main purpose of the cleaner/dryer machine is to prepare the surface of
the intercooler for powder coating. At the time of writing, APS has powder
coating done by an outside company - but this may soon change. Powder coating is
essential to protect the aluminium core and end-tanks from corrosion -
especially in areas where salt is used to clear snow-covered roads. The
intercooler can be specified with either black or silver powder coating.
Once powder coated, the intercooler is ready to be sent to its
new owner. cardboard is taped around the
precious intercooler core to protect it from damage during freighting. The 'cooler
is then boxed and sent off with the rest of the hardware included in the intercooler
kit.
The Rest of the APS Intercooler Kit...
The APS DR 500 WRX/STi kit comes with plumbing, clamps and
absolutely every part required for the conversion.
The main
sections of plumbing are made from mandrel-bent aluminium pipe, which is ultra
lightweight. The lengths of aluminium pipe are also as long as possible to avoid
having a large number of hose connections.
Hose sections are specially made to
suit. In the DR 500 kit the hose that connects the post-intercooler pipe to
the pipe that leads to the throttle is so complex that APS sourced it from
Germany. This multi-layer hose gradually changes diameter while also
passing through two bends.
The rest of the hardware that is sent out in the
parts box includes hose clamps, nuts and bolts, washers, cable ties, clips, blow-off valve adapter,
replacement coolant hoses, parts list and comprehensive fitment instructions
supported by professional diagrams.
This replacement crossbar is also included in the DR-series
'cooler kit for Subarus. Why is it needed? Well, it's difficult to fit a large
intercooler in the nose of a GD Impreza due to the space consumed by the
standard front crossbar that ties together the two chassis rails. APS gets
around this problem with this intricate replacement crossbar, which is said to
maintain the full structural integrity of the vehicle. Note that the crossbar is
presently being made from steel but, in the name of reduced weight, they may
soon be aluminium.
The APS DR 500 front-mount intercooler kit currently retails
for US$1495 or AUD$2460 (including GST) - and note that an APS pod type air
intake is also required to allow clearance for the intercooler piping.
Sure,
there might be cheaper products on the market, but now you know the level of
engineering and production know-how you're getting for your money; we haven't
seen anything in the aftermarket that comes close...
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Made for a Purpose
APS
configures its intercooler kits to suit not only the design of the vehicle, but
also a specific power range. For example, its DR 500 front-mount kit for
GD-series WRX/STis is suitable for up to 500hp while the DR 650 kit is
recommended for 500 - 700hp. What is the difference between the intercoolers?
Well, compared to the DR 500, the DR 650 core is almost twice as thick, but -
interestingly - it is slightly narrower. The narrower core allows more space for
larger end-tanks, which offer superior charge-air flow.
Not
surprisingly given its higher power rating, the DR 650 intercooler offers
greater overall charge-air flow and heat exchange performance.
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