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Although AMG rates the M156
engine from 475hp in the CLK63 to 518hp in the S63,
in reality this engine is right around 505hp, as all cars make close to 420hp at the wheels (420/0.83 = 506hp).
The
VR530 package, as the name implies, brings 63 engines to 530hp/485tq.
To assist us in testing the components, we have
acquired a white CLS63 AMG.
First we established a
baseline. This car was completely stock right down to the air filters.
1. Underdrive Pullies
We are
big fans of using underdrive pullies. Typically, by reducing the alternator, water pump and power steering pullies weights and increasing their size,
we have seen 5-12HP gains.
This is mostly seen in the first three gears as rotational inertia and gear multiplication
have a bigger effect on power reaching the ground. In all honesty we are not
really adding power to the engine, we are enabling more power to reach the ground.
The power steering pulley on the M156 engine is made out of plastic and is very close to
the power
steering fluid reservoir. There are no gains to be had changing it. The alternator and water pump, on
other hand, are heavy, cast iron pieces with room to play. Using T6061 billet
aluminum and increasing pulley sizes by roughly 10% we cut stock pulley weight
by half.
UD pullies were the first to be installed and dyno'd. We were not expecting much
gains, but we were pleasantly surprised. Although there was only a small 3HP peak
gain, HP under the curve has come up, which helps acceleration.
2. HiFlow Air Filters
Since it is very easy to
swap out filters on the 63s, we went ahead and installed our new HiFlow Air Filters
and removed the stock charcoal filters. The gains were impressive as the 63 was being
suffocated by the stock filter combination.
3. Phenolic Heat Spacers
The biggest enemy of power
is heat. As incoming air rises in temperature, it's density decreases and as a
result less
power is produced. Stock intake manifold is made out of magnesium
and becomes a heat sink after just 10 minutes of driving. In our datalogging we
have seen as much as 70F rise in Intake Air Temperature (IAT) above ambient
(160F on 90F day). Under normal street driving IAT never gets closer than 25F to
ambient air. After becoming heat soaked the car noticeably goes down on power as
timing gets retarded.
To help alleviate this problem, we have produced a set of phenolic spacers that
insulate the intake manifold from the cylinder heads and prevent heat transfer from
the heads. As a result there is a 15-25F reduction in IAT and a significantly
more consistent car.
Phenolic Heat Spacers (PHC) come with two sets of intake gaskets and new
manifold bolts.
4. IAT Sensor Relocation Harness
Now, the next obvious
question is - why not simply relocate IAT sensor up front where it can always
receive cool ambient air. The stock IAT sensor is mounted in the inlet splitter elbow by
the firewall. Without truly reducing IAT, relocating the sensor will result in
false data going to the DME and thus the possibility of triggering knock sensors as more
aggressive timing tables will be used with warm air.
Now, however, since we did lower IATs with Phenolic Heat Spacers, true IAT will
be a lot closer to ambient. To relocate IAT sensor upfront we simply left
original sensor in it's place, spliced an extension harness with water proof
connectors and added another IAT sensor now mounted up front by the driver side
foglamp.
On the dyno, the 63 loved it. IAT was the same as ambient and added 3 degrees of
timing which pushed the total gains to 24HP.
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