General Questions 

What is a crankshaft pulley?

A crankshaft pulley is the main pulley attached at the front of the
 crankshaft which drives all of the accessory pulley systems such as
 your air conditioning, power steering, alternator, oil & coolant systems.
  It is essentially the heart of the drive belt system from which all 
of the other pulleys receive their power, and thus must be properly 
designed otherwise problems & unforeseen complications may occur.

What is an "underdriven" crank pulley?

An "underdriven" crank pulley is reduced in diameter compared to
the stock counterpart in order to reduce the gearing and free up 
power.  This however can cause sacrifices in reliability and comfort 
of all those accessory systems and over time can even sacrifice longevity
of the engine due to the decrease flow of oil & coolant going to the engine. 
Although power can be made this way via underdriving, it is not recommended
due to the necessary sacrifices that have to be made.  Roughly 15% of gains
from underdriven crank pulleys are from underdriving alone, the other 85% 
comes from reduction in mass.  In addition, UD crank pulleys can irritate
their drivers by causing lights to flicker at night, stereo systems not having
as much power, increased stiffness in steering, and other annoyances.

Are AMS pulleys "underdriven" or stock diameter?

AMS has a strict philosophy in creating power only through increased efficiency
and not sacrificing comfort or reliability in order to achieve more power.  Thus, 
AMS only makes stock diameter pulleys in order to maintain OEM standards for 
reliability and comfort.  In addition, it ensures 100% compatibility with ALL
potential future modifications.  By maintaining the stock diameter our pulley
allows performance enthusiasts to ALSO run aftermarket accessory pulley systems
as well as aftermarket supercharger systems and etc.  100% compatibility is one 
of the many benefits of our design.  

How much power does this equate to?

60% (4 lbs.) reduction in mass equates to roughly 10-15HP gain at the crankshaft 
depending on model and performance modifications currently on the 
vehicle.  The more aftermarket modifications currently on the  vehicle 
the higher the gains, as it is simply improving engine efficiency percentage.  

Aren't aftermarket crank pulleys unsafe due to the 
removal of the OEM harmonic damper?

Excellent point, yes this is true.  However, the AMS crank pulley is unique in that
it DOES NOT eliminate the harmonic damper.  In fact, the stock crank pulleys have
has numerous recalls due to the OEM harmonic damper failing, so at AMS we improved
the harmonic damper to a much stronger longer lasting design to ensure the pulley
will last the life of the vehicle and this is backed by our limited lifetime warranty.  This
can not only be viewed upon as a performance modification but also as safe 
preventative maintenance to protect yourself from potential future engine damage 
due to the stock harmonic damper failing on you, it kills two birds with one stone. 

What is the difference in sound from harmonic dampened vs.
non-harmonic dampened?

It can be drastic.  Here is a short wave sample comparing the two.  The
non-harmonic dampened pulley rings VERY loudly, much like a tuning fork 
due to lacking any dampening.  Compare that to tapping our AMS pulley, 
you can barely even hear anything, all the harmonic & acoustics are 
absorb by our harmonic damper, thereby protecting your engine
from back harmonics.  

http://www.abedinmotorsports.com/pulley/nonHD-vs-HD.wav (click)

What is the physics behind the gains of a performance crank pulley?

There are numerous factors at play here.  First Force = Mass x Acceleration.  If 
the force stays constant and you reduce the mass of the pulley, this in turn will 
increase the acceleration (mass & acceleration are inversely proportional in this
equation assuming constant Force)).  In addition, Inertia = Mass x Radius² .  As 
the mass of the pulley is reduced the necessary force required to overcome inertia
is much less.  Radius does play an even more important factor as well, however 
for reliability & engine longevity reasons we cannot change the radius of the pulley
without underdriving it, which is discourage as illustrated earlier.  

Since the AMS pulley improves efficiency, does MPG increase?

Yes this is true,  your fuel efficiency should increase as well.  The amount
will vary from model to model depending on which pulley model is installed
as well as what modifications are on the car among other things.  

Does this crank pulley act much like a light weight flywheel?

Yes, essentially they do the same thing, they both reduce the rotational
mass of the crankshaft assembly thereby allowing the engine to spin &
rev more freely thereby "freeing" up more power to be sent
to the driving wheels and thereby improving real world acceleration.

How do crank pulleys differ from accessory pulleys gains?

Accessory pulley systems work as a function of RPM.  The faster
the engine spins the more power will be freed up.  This is why
most accessory pulley systems only make significant power in the 
top 15-20% of the power band.  Crank pulleys work differently. 
They work as a function of torque.  The maximum gains for a 
crank pulley are achieved where cylinder pressures are at
their peak (this is where max torque occurs).  As a result
They create excellent low to midrange torque as well
as high end HP.  The power is created at all rpms
throughout the entire power band.  Crank pulleys make
power from just past idle all the way to redline just as if
the entire power band is pushed upward on the dyno versus
just one section of the power band. 

What forms of payment do you accept?

Currently we accept any form of paypal payment as long as it is
to a confirmed address (yes it MUST be confirmed address).  The
pulley will be sent out within 24-48 hours of our purchase unless
otherwise specified.  Thanks and have a nice day!

How can I purchase one directly from the website?

Simply go to our various order pages for your specific model
 product and follow the "Order" link to make your paypal payment.

Performance Header Specifics

What improvements do your Performance Headers make?

Obviously the make answer is power.  They are designed to help the 
M112/M113 engines breathe better.  Our headers are made from T304 
stainless steel and they are TIG welded for maximum strength. We also
has incorporated thicker gauge tubing as well as thicker one piece flanges
which are superior to the competition's headers because they prevent 
warpage of the header and the header flange.  All our headers come
with a limited lifetime warranty.  Typical gains are roughly 10-15HP. 

Do I have to modify my stock exhaust to use your headers?

No, AMS chose to make a performance headers that utilized the stock 
mounting locations in order to ease installation as well as to allow our
customers the choice to remove the modification in the future.  Once 
you install long tube headers on your vehicle you are stuck with them
and cannot remove them due to having modified the stock exhaust
down pipes.  With our headers you do not have to worry about this, 
It is truly a headache free bolt on modification with no major
modification required to your exhaust system.  

Do Long Tube Headers Make More than Short Tube Headers?

The REAL answer is not really. This is a common misconception 
among Mercedes owners.  In reality a large portion of the gains from 
long tube style headers is actually from the deletion of one set of cats
in addition to larger header tubing.  If you actually do the math, 
short tube headers plus high flow secondary cats make almost the same
amount of power while still keeping the vehicle 100% street legal.
Furthermore, the secondary cats are weaker ceramic core material,
which fail more frequently, therefore it makes more sense to replace them 
anyways for maintenance purposes.  The best approach (and the most legal one)
is to use high flow bolt on short tube headers and weld in high flow 200-300 cell
secondary cats for a small fraction of the cost of long tube headers and still 
retain the stock bolt-on OEM header fitment.  Also, this route requires
no modification to be made to the stock O2 sensors or any of the
stock emissions equipment regarding to the primary catalytic converter
(or O2 sensors).   It is literally the best of both worlds without the 
hefty price tag associated with long tube style headers. 

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