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KO
Performance Technical Articles and How-To Archive
BMW Superchargers and Turbochargers 101
For E36 and E46 BMW owners.
Posted on: 12/17/04
Written by: Jim Nolden
KO Sales Manager, BMW Car Club of America
(BMWCCA) Member Club #280717, Track enthusiast,
and driver and owner of the
KO 97 E36 M3 Supercharged Saloon Track Car
Contact the author - Email: jrn@koperformance.com
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To many people, the 3 series E36 and E46 BMWs are
some of the best cars available on the market. There
is a reason these cars have been included in many
publications among the best cars you can buy, and
why so many competitors have been chasing BMW to
come up with something equal to the 3 series in
craftsmanship, quality, and performance.
As good as the 3 series BMWs are, a common question
among enthusiasts is, "How can I improve
my car even more?"
There are many ways to improve the 3 series BMW.
Some people chose to improve the suspension, while
others add a cold air intake and exhaust components…
But to make a dramatic change that will take
your 3 series BMW to Supercar Status, and performance
the likes of cars that cost two to three times as
much money, like Porsches and Ferraris, forced induction
is the clear choice.
Forced induction can be broken down into two categories.
The first category is Turbocharging. Tubocharging
makes efficient use of the exhaust gases of the
car and sends them through a turbocharger which
is typically connected to the exhaust manifold of
the car. This gives a level of positive boost that
inducts more air into the intake manifold of the
car. This condition is called boost, or forced induction.
Since the motor is an air pump it can generate more
power by inducting forced air into the manifold
of the car resulting in a higher level of efficiency
in the motor and the ability to produce more horsepower.
The second form of forced induction is Supercharging.
Superchargers create additional power not from exhaust
gases, but rather from boosted intake charges. The
intake air is fed through what is essentially an
air compressor that takes the intake air and compresses
and accelerates it by means of a supercharger. The
supercharger isn't driven or powered off of exhaust
gases like a turbocharger, but is instead powered
by a belt driven by the crank pulley of the car.
The crank pulley turns the supercharger so the power
is linear with the revolutions of the motor. You
will not experience "turbo lag" with a
supercharger since it doesn't take time to spool
up, but rather builds power as the revolutions of
the car increase.
Which is better?
The answer really comes down to a matter of choice,
personal preference, and goals for the performance
of the car. Let's take a closer look at features
and benefits of each…
Turbochargers:
Turbochargers are capable of producing more horsepower
than superchargers in almost every circumstance.
They also are capable of producing more torque
than most superchargers.
You may be saying to yourself, "So if they
can produce more horsepower and torque why doesn't
everybody choose a turbocharger?" Well,
in a word, money. Turbochargers cost much more in
most cases. But for the person looking to really
make big horsepower, turbochargers are the way to
go. Turbochargers cost more because they have more
parts and are more complicated than superchargers,
thus requiring more design work for a more complicated
system. They also are far more difficult to install
than a supercharger and require an intercooler.
Turbochargers also generally require that the car's
compression be lowered to operate the engine at
a safe level.
Tuning can be adjusted far more easily with turbochargers
since boost levels can be controlled by electronics
and aren't dependent on the revs that the car is
running at. Therefore advanced tuning can be
accomplished by turning up the boost level and doing
additional software tuning. This can also require
additional hardware such as larger intercoolers,
beefed up internal components and larger injectors.
To really build up a huge horsepower car, the turbo
has the most expandable capabilities.
So what are the downsides of turbos? The answer
basically comes down to the buyer's limitations
of funds. A Stage II Active Autowerke kits run around
$11,000. Installation typically runs around $4,000.
There are, however, a few other things that some
people don't like about turbos. Turbos can have
what is called "turbo lag". This is a
time delay between when the turbo spools up and
actually starts to deliver boost to the car, and
when the driver presses the accelerator down. This
is usually more noticeable at lower speeds. Smaller
turbos will produce less lag time, and less power,
while a larger turbo produces more power but more
lag. It is a trade off, and tuning can remove
a lot of these limitations, but none the less, it
is a common knock on turbos. The other consideration
is drivability. Turbo power is not linear. It is
very much more like an on/off switch. When the turbo
starts making boost, power is delivered very quickly.
Since it is driven off of the exhaust gases it produces
power when the spool up of the turbo has occurred
and produces boost very quickly. This results in
surges of power and torque in a very quick rush.
If you are driving this car on the track this can
be a trait you don't necessarily want. Boost coming
on at the wrong time can be a dangerous thing on
the track or street if in the hands of an inexperienced
driver. No one wants to spin out in a turn from
an unexpected surge in power at the wrong time.
Just how much horsepower can you produce in a
Turbocharged E36 M3? It is possible to reliably
build a 600 horsepower car with a turbo.
For example, a Stage II Active Autowerke Turbo Kit
will produce about 450 horsepower and 369 ft/lbs
of torque.
Let's take a look at supercharging...
Supercharging is the second form of forced induction
and produces similar results to turbocharging through
a method of accelerating intake charges through
a compressor or "supercharger". Intake
air charges are run through the supercharger which
is driven by the crank pulley of the motor. This
linear effect drives supercharger revolutions based
upon the revs that the car is running at. So acceleration
and power will come on in a very smooth linear effect
across the entire power band and will reach maximum
horsepower as redline approaches. Since the supercharger
runs off of the intake charge it is not always necessary
for supercharged cars to have an intercooler since
the air charge is not from the hot exhaust gases
of the car but rather the cooler intake charge from
outside air.
Superchargers are far less complicated than turbos,
and typically can be bolted on to existing components
without doing any internal engine work. They
will usually bolt on to existing hardware in the
car and require little if any permanent modifications
to the car in order for them to function properly.
They also don't require all the hardware a turbo
needs since they don't use a modified exhaust manifold
and don't require the car to have the compression
lowered in order to function safely.
Superchargers will produce very good horsepower
numbers, and in almost all 3 series BMW applications
you will see an additional 100 horsepower,
and usually another 40-50 ft/lbs of torque.
All of this power will come in to play in the 3k
to 4k RPM range on a 3 series BMW. These conditions
make a BMW Supercharged 3 series extremely drivable.
For street purposes the supercharger is a very fun
car to drive. It doesn't have any of the turbo attributes
of going from lag to boost quickly. The supercharger
is usually very seamless, and feels very much like
the car did being normally aspirated (non-boosted
/ pre forced induction), only with much more power.
So what are the features and benefits of a supercharger?
BMW Superchargers cost far less than turbo kits
and can produce similar results although they are
not as expandable as a turbo kit for advanced tuning.
They are usually fairly simple to install, and
don't require modifications to the motor or require
complicated hardware to function properly.
They don't exhibit "turbo lag" and produce
very linear smooth power that is easy to control.
There are many choices for a 3 series BMW supercharger
vs. available choices in turbos. Many tuners have
spent a lot of time and money in developing and
improving superchargers for street applications,
whereas there are only a very few BMW tuners offering
turbo applications.
Now that we have discussed the basic principals
of forced induction, lets talk about each of the
kits that are out there and find out which kit
is the right kit for you!
Superchargers are available in many different types
and sizes. For this purpose we will look at the
most common kits available for the 3 series BMW.
The first BMW supercharger we will discuss, and
also the most common BMW supercharger used is powered
by a Vortech blower unit. Vortech is the most
common supercharger you will see in most BMW applications.
This is the choice of ESS's E36 kits, along with
Dinan. Vortech Engineering designs and builds superchargers
that don't need to have an intercooler integrated
into their systems. Vortech does this by using a
very efficient blower that doesn't generate high
temperatures that would require an intercooler at
5 to 8 lbs of boost. Vortech kits are also expandable
(although Dinan won't ever admit this)! Additional
boost can be run in these units with the use of
an intercooler or aftercooler for even higher performance
levels. KO Performance has engineered, and
designed a Stage
II Boost Kit for Dinan and ESS Vortech BMW Superchargers
that allows for the normal boost levels in a
standard Dinan, or ESS kit of 7
psi to safely be increased to 9.5 psi for
additional horsepower and torque reaching almost
turbo levels!
The second type of supercharger (blower) is Rotrex.
One of the biggest BMW tuning shops in the USA,
Active Autowerke, uses the Rotrex blower for its
ability to produce more low end torque than Vortech
units . Rotrex does this by running at higher rpm's
than the Vortech unit. The by-product of this feature
though, is higher temperatures. The Rotrex supercharger
generates more heat since it runs at higher revs.
Active Autowerke properly engineered their system
to incorporate an intercooler, and an oil cooler
to address the heat issues from the Rotrex blower.
The oil cooler helps keep oil temperatures under
control for the blower. This supercharger
setup actually has its own oil supply that isn't
dependent on the engine's motor oil. This results
in a kit that doesn't heat the engine oil to an
unnecessarily high level due to it serving duel
duty as the engine and supercharger oil supply.
Active Autowerke kits are not expandable and will
not be able to be added on to like a Vortech kit.
The third type of blower in production right
now is the ASA blower. ESS (European Supercharging
Systems) has begun releasing BMW supercharger kits
using ASA blowers. The ASA supercharger has a
unique advantage that the Rotrex and Vortech kits
don't have. It has a clutch that engages past 1k
rpm. The advantage to this is that the supercharger
is not being driven and producing heat when the
car is idling! The ASA blower runs very similarly
to the Vortech kit, in that it doesn't need an intercooler
to reliably produce horsepower, and is expandable
like the Vortech kit is. Another great feature is
the fact that it isn't producing the heat levels
the other two types are, because it is not engaged
at low RPMs. For the cars that sit in traffic, or
are often idling, this is a major advantage for
people that do a lot of driving in dense population
centers, and other high traffic areas. These blowers
are new to the BMW supercharger market, but not
to tuning in general, and are very reliable and
safe supercharger kits to add to your BMW.
So, now that you know the basics of superchargers
and the three types of kits available for BMWs,
how do you choose what is right for you?
Here are some good questions to ask when considering
BMW superchargers for your vehicle.
1. Do I ever want to expand on the horsepower
that I will be adding, or is this as far as I want
to go?
2. Will this car be driven in hot climates that
may require an intercooler and oil cooler?
3. Do I drive a lot in traffic where the heat generated
by a supercharger would cause me to heat soak the
motor?
4. Do you plan on putting this car on the track
where heat would be an additional concern?
The best way to answer those questions is to research
as much as you can, and find out the differences
between the BMW kits available on the market, or
call and speak with one of our qualified Performance
Specialists on staff at KO Performance.
A KO Performance Specialist can help you
get the answers to the questions you have, and
make sure you make an educated decision that you
know you will be happy with.
You can enjoy some peace of mind in knowing that
KO Performance carries only the best BMW
performance parts available, and we only supply
products that we know work, and are from the best
names in the business. The one constant among all
these kits is that they are all very good, and you
can't really make a bad decision with any of them.
The last bit of advice I can give you is DON'T
PAY MORE FOR LESS! Dinan has, for years,
dominated the BMW tuning industry with their name
and reputation. Unfortunately they also charge a
premium for that name and reputation. All of
the BMW supercharger kits on the market are built
to the same or better standards than Dinan.
Many of the other kits are also designed to be expandable
as well, to allow for additional tuning. What Dinan
won't tell you is that there are other people
and companies that have also spent countless hours
tuning the 3 series BMW and charge far less for
their kits, while producing similar results!
Dinan makes great BMW supercharger kits but so do
Active Autowerke, and ESS (European Sugercharging
Systems). You will find all of their hardware to
be first rate and their tuning excellent. Call
and find out for yourself before you pay too
much for a Dinan kit.
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KO Performance offers the BEST PRICES on BMW
superchargers and turbochargers GUARANTEED!
Test
us on this… you'll be happy you did.
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Bimmer May 2006 Feature "Hammer of the Gods" -
• KO's E36 M3 Stage III  Supercharger Kit unveiled to the
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