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1)
What is the difference between headers and
extractors?
2)
What is the difference between a TRI-Y and a 4-into-1
design?
3)
Why don't car companies fit them as standard?
4)
How much increase in power will I get?
5)
Will my fuel economy improve?
6)
What is scavenging?
7)
Will headers make my car louder?
8)
Can I fit them myself?
9)
What are mandrel bends?
10)
What is ceramic coating?
11)
What is a cat converter?
1)
What is the difference between headers and
extractors?
None! In Australia, headers were known as extractors
through the 60's and 70's by the pioneering companies
that developed them. In America at the same time they
were coined headers (also spelt hedders). This was in
part due to the fact that they (headers) are an
extension of the cylinder head. In the 80's new
Australian companies, along with the established
industry, began to market extractors as headers. The
main reason being that these companies intended to
change the image of the humble extractor to more of a
common vehicle replacement component. Some 'old school'
enthusiasts still call them extractors today.
2)
What is the difference between a TRI-Y and a 4-into-1
design?
A 4-into-1 design is perhaps the most traditional
design. This design is common to the US market and is
well used within the drag race fraternity. The basic
principle behind the design is that the scavenging
effect within the collector cone effects the three
remaining pipes (in a V8 half), instead of limiting the
pulse to the very next pipe in the sequence. This
generally results in a header that performs very well in
the mid-range to top end of the engines performance.
A TRI-Y on the other hand splits the firing order evenly
and uses the secondary pipes as sequential collectors.
This results in generally a greater scavenging effect
due to the fact that scavenging is achieved at 2
different points in the header design, firstly at the
primary to the secondary collector and secondly to the
secondary outlet collector. Generally this improves
torque in the lower to mid range performance of the
engine.
Both designs are usually more efficient than a standard
manifold and both offer distinctly different advantages.
3)
Why don't car companies fit them as standard?
There are two main reasons, firstly like all things,
vehicles are made to a standard and a cost. The cast
iron standard manifold will always be the cheapest way
of producing an exhaust manifold. However, car
manufacturers do know the benefits of a tubular designed
exhaust headers and indeed generally do offer this type
of product on a sports related sedan, eg. HSV, Tickford/FPV,
etc. These tubular manifolds are still better than a
standard manifold but are still limited to cost, and as
such are a compromise in design.
Secondly, cast iron manifolds can be cast into awkward
and different shapes to accommodate steering boxes, etc,
and can be installed onto the engine along with all the
other necessary bolt on components during engine
assembly and with the engine still able to be slotted
into the body during the vehicle build. Headers however
will generally take on a different proportion and often
can wind themselves around steering components, etc,
which in turn would slow down the vehicle build time
process.
4)
How much increase in power will I get?
In most cases around 10% is quite achievable. This may
mean if you have, for example, a 4WD vehicle delivering
around 70 kilowatts at the wheels you could expect
possibly 6 to 10 kilowatts increase. If you have a V8
5.7 Litre commodore with around 160 kilowatts at the
rear wheels you could expect to reach 170 to 180
kilowatts. This is just a generalisation and other
factors do become involved. Cold air intake and open
exhaust systems encourage the full effect of a well
designed set of headers.
5)
Will my fuel economy improve?
In most cases, yes. Due to the scavenging effects of an
efficient design of headers, more clean air fuel mixture
can be delivered into the cylinder bore resulting in a
more powerful power stroke. Quite simply this means that
the engine does not have to work as hard to deliver the
same power. The biggest cause of excessive fuel
consumption in this case would be driving behaviour.
Quite often once a set of headers and a new exhaust
system is installed the driver will tend to drive the
vehicle a little harder than usual because of the new
found audible experience along with the increase in
power. This is when the vehicle can use more fuel. Fuel
consumption will generally decrease once the vehicle is
driven over a long distance and at a constant speed.
6)
What is scavenging?
Scavenging is one of the most critical parts to a design
of a header. The tubes volume (diameter and length) is
chosen to represent a discharge of spent fuel or pulse
being discharged from the engine at a given rev range
(usually mid to top end), without competing with the
next charge. This pulse then enters the collector cone
with a greater volume than the surrounding connected
pipe(s). This creates a low pressure (or vacuum) at the
exit of the next pipe. This vacuum then in turn sucks at
the next pulse travelling through the next pipe in the
sequence, vacuuming or scavenging the cylinder bore
clean. This aids towards an unpolluted cylinder bore,
ready for the next clean dose of air fuel mixture.
7)
Will headers make my car louder?
The simple answer to this is 'no'. Headers by nature do
not increase the Db range by themselves. The main reason
for any exhaust system to increase the sound level is
found in the choice of mufflers. Car manufacturers
choose to use very restrictive but sound efficient
reverse flow mufflers. These mufflers are very effective
in reducing noise levels but also are very restrictive
in flow. Some after market mufflers are very good in
producing a high flow rate while still remaining within
the law. Other mufflers are just too small in shape or
too big in pipe diameter to do the job of effectively
quieting the vehicles emissions. All customers wishing
to alter their vehicles exhaust system should check with
their states regulatory authority and work with
reputable exhaust shops. Headers however do deepen the
sound of the note of the exhaust. Much like a flute, if
the pulse travelling down the barrel is allowed to
escape through the first hole a high pitch is audible,
however if the same pulse is allowed to complete the
journey to the end, a much deeper note is heard. Headers
by their design will have longer tubes than a standard
manifold, creating a deeper note.
8)
Can I fit them myself?
Yes. All Pacemaker products are supplied, when required,
with all necessary additional nuts and bolts, EGR and 02
hook-ups, brackets and comprehensive fitting
instructions. However, the days of fitting headers at
home are rapidly changing forever. With the addition of
sensors, plastic and rubber components, computer systems
and in some cases intimate knowledge of fitting
procedures, such as the removal and replacement of
critical components, the job is growing far more
difficult than in previous years. Pacemaker thoroughly
recommends that the customer seek the expertise of a
reputable exhaust shop operator.
9)
What are mandrel bends?
A mandrel bend is the result of a process in which the
tube is bent to maintain its original diameter. A
mandrel or ball link die is inserted internally during
the critical point during the beginning and at the end
of the bending cycle. It is this procedure that gives
the pipe a uniform appearance while maintaining the same
internal volume capacity through the bend. For a visual
explanation of this process, please visit the technical
information page,
Here.
10)
What is ceramic coating?
Ceramic coating is a thermal skin applied internally and
externally to the header. This skin or coat, apart from
other properties, consists of ceramic and aluminium.
This combination provides very high thermal resistance
and is an ideal coating for headers, pistons and other
high temperature components. A by-product of ceramic
coating is its high lustre or finish, and should
increase the life of the product. We at Pacemaker
recommend the use of ceramic coated finishes on all of
our products.
11)
What is a cat converter?
A cat (catalytic) converter is an necessary part of the
emissions control of any new vehicle since 1986.
Essentially the cat converter is a strainer placed close
to the engine (usually before any mufflers) to capture
all impurities and most noxious gases that are produced
during a fuel cycle burn. Most Pacemaker products are
designed to be used with factory supplied cat
converters.
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