UPDATE! Highway testing now completed. Here's the
Highway testing data. More detailed
The aftermarket for the 1.8T has been booming, as people come
to realize the potential of this stout motor in a relatively light
chassis. Up until now, the upgrade path for the stock intercooler
has been to replace the stock Sidemount intercooler(SMIC) with
a larger unit, or to scrap it altogether and go with a Front Mount
unit(FMIC). It has been held as common knowledge that SMICs are
inferior to FMICs in all performance applications. Regardless
of turbo, horsepower, vehicle use, FMICs have trumped SMICs in
popularity. Part of this due to the fact that all the big horsepower
cars run FMICs. The other part seems to be that it is inconceivable
to many that an SMIC can indeed perform equal to an FMIC. The
goal of the TyrolSport UG SMIC was to combine the performance
of an FMIC with the cost and easy packaging and installation of
We spent the better part of a day today
testing three intercoolers. The stock sidemount, The TyrolSport
UG side mount(Known as the UG SMIC in the charts below), and a
front mount. The aftermarket FMIC will not be named for many reasons.
The TyrolSport UG SMIC mounts in the stock location, uses stock
hoses, and requires minor trimming to fit. The UG SMIC uses a
bar and plate Bell intercooler core. The Front Mount is a popular
unit, and resides on many 1.8Ts. We will not reveal the manufacturer
of the FMIC, as the purpose of this test was data acquisition;
not marketing, sales, or slander.
Core volumes(LxWxH) for each respective
unit were as follows:
Stock 218 Cubic Inches
UG SMIC 355.5 Cubic Inches
FMIC 340.1 Cubic Inches
Endtank volume was not measured, as the
complex shape of some made it an exercise in futility. The FMIC
appeared to have the largest endtank volume, and the stock IC
appeared to have the least.
The test car was a 2001 GTI equipped with
an APR Stage 3, a Milltek catback, and an N75J valve. The car
was equipped with a catalytic converter. We decided to use an
APR stage 3 because the power level is in line with what most
people shoot for. The car was mechanically sound, with no fault
The testing procedure was as follows. The
already warm car was driven 20 minutes to the dyno, and strapped
down. The engine and ECU were not touched before, during, or after
the whole dyno process. Fuel trims were not reset, the battery
was never disconnected, and no ice was placed on the intake manifold.
The car was filled with Exxon 93 octane fuel from a local station
prior to the dyno. In other words, no "tricks" were
employed to skew the results(and believe me, we know many that
can be used to spin dynos in a desired direction). Please note
that all units were tested using SAE correction factor.
All of the intercoolers were tested with
a stock GTI bumper cover. When testing the sidemount units, we
removed the right lower grill. When testing the FMIC, we removed
the center lower grill. A fan was placed pointing towards the
right lower grill for the SMICs, and then moved to the center
for the FMIC. The stock unit was tested with the factory shroud
in place. The UG SMIC did not use the shroud as it could not be
fitted with the SMIC in place.
The dyno order went as follows: UG SMIC,
Stock SMIC, FMIC, UG SMIC. We did this in order not to give advantage
to the UG SMIC as it was very cold outside on the way to the dyno.
Each unit was run 5 times, approximately 2-3minutes apart. The
timestamps are evident on the dyno sheets below. The car was idled
between dyno runs, and was only shut off when swapping the intercoolers
themselves. All runs began as close as possible to 2500rpm, and
then went full throttle to 65-6700rpm.
We datalogged with VAGCOM simultaneous to the dyno. We did not
datalog the first run of each unit, as they were all near frozen
from being left in the shop overnight. We did however include
the dyno data from each of the first runs, as this would represent
the old "driving down the highway and running into race"
scenario. Data blocks used were 003, 022, and 118. This allowed
us to log boost, rpm, ignition timing, inlet temps, and knock
correction factors for cylinders 1 and 2. We did not have enough
blocks to log cylinders 3 and 4, but experience has shown us that
cyl.2 is the one that typically runs leanest, and can be used
as an early bellweather to impending engine meltdown. This was
validated in our testing, as Cyl.1 for the most part showed no
knock correction, while cyl.2 showed significant amounts during
various portions of the test.
The bumper cover was affixed with two screws,
and we practiced the intercooler swapping prior to the dyno. We
were able to change them in approximately 10-15 minutes, with
the car strapped to the dyno.
Please be aware that we are not claiming
that our FMIC results are indicative of all FMICs on the market,
or that the unit we tested is the best unit available. We are
also not claiming that our UG SMIC results are indicative of other
SMICs on the market. The results presented are limited to the
three particular units we tested today, and no others . These
intercooler results also cannot be projected for higher horsepower
vehicles, and we make no claims as to their accuracy when surpassing
the whp levels presented in the test.
The data will be shown in the order of
The first 5 runs were on the UG SMIC, and
are presented here:
This unit was very consistent in it's power
delivery. Please do not look at the absolute numbers, but rather
the changes between the five runs, as the power numbers are right
in line with most "stock" APR stage 3s on pump gas.
Since we are eliminating the first run, we will set the official
max power of this unit at 254.9hp, and 264.2 torque.
The next runs were with the factory sidemount:
The first thing to notice is the huge inconsistency
in the powerband with the stock SMIC. The other big news is the
consistent power loss vs. the UG sidemount. Eliminating the first
run, we get a max power rating of 245.2/261.7.
One of the most interesting things we found
is that ALL THREE units dipped to their lowest power after their
respective third or fourth runs, and then began REGAINING power.
Strange huh? Our hypothesis is that after the third run, the ECU
began adapting to each respective IC to maximize it's power potential.
This is purely conjecture, but is very interesting to note. Again,
the ECU was not cleared at any time during this test.
After the Stock SMIC, we installed the
FMIC and began testing:
To our surprise, it showed some improvement
in midrange torque, but overall horsepower was very similar to
the stock SMIC! Eliminating the first run, the max power came
on the fourth run, with 244.6 horsepower, and 269.8 torque.
To verify that our first few runs on the
UG SMIC were not flukes on a "cold" motor or IC, we
reinstalled it after the FMIC. To our surprise, it actually performed
better than the first time around.
Here is the second set of runs of the upgrade
The second run of the upgrade SMIC had some more inconsistency
than the first, but overall power levels were the same over even
higher than in the first set of runs.
To make this analysis easier, here is the
third of five runs for all the intercoolers, from the horsepower
perspective, followed by the torque perspective. Stock SMIC is
RED, FMIC is GREEN, UG Sidemount is BLUE and PURPLE:
The FMIC has a bump in midrange HP and
Torque, but is equaled or eclipsed by the SMIC at higher revs.
The stock SMIC trails significantly. We were not going to let
these intercoolers off so lightly. Why was the FMIC not producing
the power it should be? What are boost and power levels? For that,
we turn to the VAGCOM datalogging.
We first looked at Intake Air Temperature.
The following chart is an average of the last four runs(first
Average inlet temps show the stock IC lagging significantly behind
the UG SMIC and FMIC, with the FMIC showing a small advantage
over the UG unit at 6500 rpm. This does not explain why the FMIC
was down on horsepower, but does show why the stock IC had the
least amount of power overall.
Next we analyzed boost levels:
It seems as if once they were all fully spooled, the boost pressure
average were the same, so none of the units really showed any
restriction compared to the others. The FMIC did trail significantly
in spool time, so the common belief that the piping of an FMIC
slows spool seems to have held true in our tests.
Still no answer on why the FMIC did not
produce the results it should have. Here is a chart on ignition
timing for all the units:
The Upgrade sidemount shows the least amount
of timing advance during spool, yet makes more power during that
timeframe. (Whether a function of the increased boost level shown
above, or perhaps less restriction). Up top, We see part of the
reason why the FMIC is down on power; it shows the least timing
advance in the 5500-6000 rpm range, which should be where the
peak power is produced.
Now why on earth would this happen? Here
is an analysis on knock voltages on Cyl1(first chart) and Cyl2:
The UG SMIC was the only IC tested to not show any knock on Cyl#1,
in either run, whereas both the stock and FMIC showed knock on
#1 starting where the boost curve reached its' peak. On Cyl#2,
the stock SMIC shows a consistent increase in knock voltage, almost
similar to its' performance in #1. The FMIC shows the same results
in both chart, increasing knock with the onset of maximum boost.
The UG SMIC, although it performed perfectly on Cyl#1, showed
the highest initial knock on Cyl#2, followed by a consistent drop
to redline, even after reaching peak boost. The lower timing advance
for the FMIC in the 5500-6000 rpm range is a function of the ECU
looking at the combined knock voltage of Cyl#1 and #2, which would
look like this:
The fact that both stock and FMIC are showing
much higher knock correction in the upper RPM range explain the
poor power results.
This is not going to be the last test of
these three units. As soon as the snow clears here in NYC, we
will be testing all three units again, but this time on a closed
course. We will be running the units from 60-120mph, in two directions,
on the same day, using VAGCOM datalogging. This will separate
the men from the boys.
As for now:
Myth: SMICs are always inferior to FMICs.
UPDATE! Highway testing now completed.
Here's the Highway testing data. More
detailed pictures here.