Tech - Street Commodores

EXHAUST BUYER’S GUIDE
An Exhausting
Decision
THE EXHAUST SYSTEM IS NOT ONLY ONE OF THE FIRST MODIFICATIONS
PERFORMED TO ANY COMMODORE, BUT ALSO ONE OF THE MOST FLOODED
MARKETS AS FAR AS BUYER CHOICE IS CONCERNED.
CHOOSING AN EXHAUST IS ONE DECISION YOU DEFINITELY DON’T WANT TO
GET WRONG, SO HERE ARE A FEW THINGS TO LOOK OUT FOR
Story by Jack Drewett Pics by Chris Sorgsepp and SC Archives
s far as our good
friends at the EPA are
concerned, the primary
function of a vehicle’s
exhaust is to prevent
dangerous gases from
poisoning their pink, virgin, hippie lungs.
As such, a whole host of legalities need
to be considered when swapping over to
an aftermarket exhaust.
This is not to say that it cannot be
done legally, but simply that when doing
so, a bit of thought, knowledge and plain
common sense must go into it.
All of the shops detailed within this
article will not only be able to point you
in the right (or wrong, if you wish to run
the RBT gauntlet!) direction regarding
such legalities. They will also be able to
supply and fit a killer exhaust for your
Street Commodore. Special thanks must
go to Hi-Tech Mufflers for supplying the
exhaust cut-aways.
A
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CAPA
www.capa.com.au
CAPA is the creator of some of the most
popular exhausts in the modified scene.
It offers a massive spread of Commodore exhaust products, with nearly all
models covered including the V8-powered VEs.
CAPA offers a full line of products
covering all driveline componentry options from VZ right back to the trusty old
VL. The company also offers its exhausts
in a range of finishes including ceramic
coating, high-temp paint, stainless steel
or mild steel. To ask for more would be
just greedy!
TAKING US AROUND THE BEND?
Many exhaust companies charge an absolute premium when it comes to offering
an exhaust with which a mandrel bender was used to create. These mandrelbent systems claim higher flow rates, improved fuel economy, better aesthetics
and, of course, a better sound. But is it really necessary?
Why spend $900+ on a single-pipe system when you could get the equivalent
press-bent performance system in the same diameter for less than half the cost?
The answer is it all comes down to horses for courses. Yes, it is true that a
mandrel-bent system will outperform the same system using press bends; however,
what is not so clear cut is whether the extra price often thrust on buyers is justified.
The answer is twofold. For a high-performance engine where the power gains from
exhausts can be phenomenal (such as an LS1 or RB30ET), the higher price of the mandrel-bent system directly translates into a better-performing car on the street.
However, when choosing an exhaust to suit your standard Holden or Buick
six, there is little likelihood you would notice any real-world difference – as
far as performance is concerned – using a mandrel-bent system instead of a
press-bent one.
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A typical factory muffler – big, heavy and
restrictive. There are
solid gains to be had by
swapping mufflers like
this over to a straightthrough design system
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EXHAUST BUYER’S GUIDE
www.castlehillexhaust.com.au
The last thing poisonous gases
see upon having completed their
tour of duty, as far as power
production is concerned
STCOM128_36_CastleHillExhaust.in1 1
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Castle Hill exhaust will not only supply
and fit almost any brand of exhaust
you could possibly desire, but can
also make up custom exhausts and
manifolds in house, perfect for that
tricky conversion – or for when something off the shelf simply won’t cut it
for your special Commodore. The on
site enclosed dyno hints to the level
of seriousness with which these guys
take their work.
EXHAUST TERMS
• Cat back – This refers to the part of an exhaust running from the catalytic converter onwards to the rear of the vehicle. A cat-back system
will give little performance gain if it is not combined with a higher
flowing and suitably sized catalytic converter and header/manifold
set-up.
The sound quality will also be significantly reduced in comparison
with a complete exhaust system.
• Turbo back – Obviously only applicable to turbocharged engines,
turbo back refers to an exhaust system that runs from the turbocharger exhaust housing (not including the actual housing, however) to the
very rear of the vehicle.
For example, a ‘3in turbo back’ system consists of a 3in dump
pipe connecting to a front pipe of the same size. Then it moves into
a 3in flanged catalytic converter, which is followed by a 3in cat-back
system.
• Straight through – Generally refers to an exhaust system using
straight-through mufflers (as opposed to offset entry and exit mufflers) for a greater reduction in backpressure.
• Extractors – Another name for headers, extractors is a term only
really used here in Australia. It describes an aftermarket replacement
for the factory exhaust manifold, being the initial part of the exhaust
system bolted to the cylinder head. Very rarely are performance turbo
exhaust manifolds referred to as extractors.
• Diff dumper – An exhaust system ending underneath the vehicle,
usually over or before the rear differential.
• Flanged off – Refers to an exhaust system that can be partially
unbolted to make it more flexible for street/strip use. Many systems
flange off just before the diff, so the rearmost part of the exhaust can
be removed for the racetrack etc. Many flange systems can also unbolt the rearmost muffler so it can be exchanged for another without
the need for welding.
• No kitty – This slang term is commonly used and is a reference to an
exhaust system that lacks a catalytic converter, whether it was offered without one from the factory or has had it removed.
Removing a catalytic converter is likely to get you put away for 25 to
life if you get pulled over, so we wouldn’t recommend it.
R
CASTLE HILL
EXHAUST CENTRE
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EXHAUST BUYER’S GUIDE
DI FILIPPO EXHAUST
A closer inspection reveals the
honeycomb-like construction of the
element. This area will heat up to over
800°C under normal operation, with
the unit being inefficient while cold
www.darrendifilippo.com.au
Di Filippo’s wide range of mandrel-bent
exhaust systems are some of the best
on the market, and cover the majority of
performance Commodore variants.
Extensive R&D goes into the creation
of each Di Filippo product and this is
obvious on the street/track, with the
exhausts looking, sounding and flowing
incredibly well.
HITECH MUFFLERS
www.hitechmufflers.com.au
Driven by Lambros Kouriefs, whose exhausts date back to
1974, HiTech muffl ers is one of the slickest, most up-to-date
and genuinely performance-oriented exhaust companies in
Australia.
Unlike many performance parts available on the car market,
HiTech products are all produced right here in Australia – more
specifically the HiTech factory is in Bathurst! HiTech exhausts offer
excellent performance and are some of the best-looking systems
on the market. Combine that with a 10-year warranty and you’ve
got a very viable option in HiTech.
FROM THE HORSE’S MOUTH
Lambros from HiTech mufflers tells all.
D&T PERFORMANCE
SC: Would you say that a mandrel-bent
system is always the better choice for
a street car?
L: Mandrel-bent systems are for
high-performance applications, not
so much an everyday car. The gains
on a street car are not as noticeable as in a full-house performance
application.
High revving, high-performance
vehicles need minimal restrictions.
They need to get every last bit of
exhaust out in a hurry. In a normal
everyday car, especially with
regular mufflers, there are no huge
gains to be had.
D&T performs a whole host of operations,
including custom fabricated and off-the-shelf
exhaust systems. D&T has already developed a
system to suit the mighty 6L VEs and offers it as
both cat-back and full systems.
As with many of the more serious workshops, the company has its own dyno and will
perform brake/suspension upgrades to help
your Commodore cope with its new-found
power, if you so desire.
SC: Apart from aesthetics, what differences could be expected from a
stainless steel system compared to
the equivalent mild steel set-up?
L: Appearance and sound aside,
stainless systems don’t corrode
like mild-steel types, so the metal
doesn’t deteriorate and flake inside, which can cause potential
issues over time.
www.dtperformance.com.au
GENIE HEADERS
www.genieheaders.com
Packing over 40 years experience in
working with cold, hard steel, Genie’s
massive amount of knowledge in the
industry translates directly into the high
quality of its products.
Genie supplies and fits headers for
nearly all makes of Commodore, including
the 186/202-powered early girls. Genie’s
long-time claim that its extractors improve
both performance and fuel economy has
been proven by the company’s success
over the past four decades.
SC: Is a higher-fl ow catalytic converter essential in a sports exhaust
system, or are the gains as minimal
as people claim?
L: There are great gains to be
had from the fitment of a high-flow
catalytic converter. For example,
fitting a stainless high-flow cat to a
Subaru WRX alone sees the boost
pressure rise by 2psi due to the
engine being able to breathe. While
a regular ceramic cat may flow
470cfm, a stainless high-flow unit
will flow 780cfm.
SC: Does gutting a cat give roughly the
same result?
L: Not at all. Gutting a catalytic
converter can cause a range of
issues, including fines of up to
$33,000.
SC: What considerations would you
have to make when it comes to choosing a muffler for a turbocharged exhaust system, as opposed to naturally
aspirated?
L: Turbocharged engines push
around twice as many gases as
the equivalent aspirated set-up, so
with the turbocharger providing
backpressure, the less restriction in
the exhaust, the better.
SC: What is the benefit of fitting hot
dogs to an exhaust system?
L: Lots of noise, and that’s it.
SC: Do you find that differently shaped
cut-offs on exhaust tips lead to an
overall difference in exhaust note?
(Popular rumour being angle cuts can
give a deeper ‘burble’.)
L: No, the tips are purely cosmetic.
SC: Does running fewer mufflers really
make a difference on a street car? Is it
counterproductive on a stock naturally
aspirated engine due to a drop in backpressure?
L: On a street car, you are legally required to run as many muffl ers as the vehicle was equipped
with from new. The exhaust
system must also comply with any
dB restrictions placed upon it by
the relevant authorities. Removing muffl ers just creates a lot of
noise. A good straight-through
muffl er gives very little reduction
in exhaust fl ow.
SC: Are there any situations in which diff
dumpers or side pipes are legal?
L: Side pipes are generally okay
as long as they exit 18in or more
back from the last window.
Dump pipes, on the other hand,
are always illegal and a bad idea as
they cause fumes to come into the
car’s cabin.
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EXHAUST BUYER’S GUIDE
PACEMAKER
www.pacemaker.com.au
Pacemaker has been wowing the mates of Commodore enthusiasts for longer
than many of us car to remember. Its reputable name and stylish pale-blue
paintwork sets its products apart from a rather large and competitive field.
Pacemaker offers exhausts to suit every single Commodore built (and no,
the Starfire-powered vehicles don’t count), from VB to VE, V8s as well as the
sixes. They are high quality, well priced and instantly recognisable products,
which makes their popularity no great surprise.
Pacemaker is highly active on the development side of things, and
combines its effective ‘pipe over cone’ technology with efficient R&D. This
enabled Pacemaker to be one of the first to release performance headers for
the six-cylinder VEs.
IN THE HOT SEAT
www.hmheaders.com.au
HM has been producing exhausts for HSV
since its birth nearly 20 years ago. That
alone gives a strong indication as to the
ballpark in which its workmanship lies.
Not only that, HM offers an absolutely massive range of Commodore
exhausts, including early model HDT
headers that run without gaskets! The
range of HM exhaust products extends
from there to include a range of different styles of exhaust to suit most
Commodore applications.
The mufflers from the new VE Commodore look somewhat like a maze as far as
airflow is concerned. They do a great job of
choking the engine out of valuable power
and should be ditched as soon as possible
LUKEY
PERFORMANCE EXHAUSTS
www.lukey.com.au
Lukey tells us that its exhausts are so distinctive,
you can actually hear the difference between a set
of Lukey pipes when compared to other aftermarket headers. Not only do its pipes sound different
to any others on the market, Lukey also says its
gear will deliver better economy and more power.
Lukey stocks entire systems as well as individual components for most models.
We quiz Pacemaker on some of the fundamentals of Commodore exhausts.
SC: As far as coating is concerned,
which do you believe to be superior?
PM: Although our systems are
supplied finished with high-temp blue
paint, for longevity you simply cannot
look past ceramic coating. We have
our own ceramic-coating company
in-house.
SC: Do you believe a full exhaust must be
fitted to see serious gains? Or can noticeable increases be brought forth by the
fitment of simply one part of the system?
PM: Definitely go for the entire
set-up. The exhaust must operate as
one complete system. An exhaust
system can give serious gains when
matched correctly. We recently had a
VZ Alloytec come in and saw a gain of
19rwkW purely from swapping over
the headers, cat and exhaust.
SC: Which style of header do you believe
performs best?
PM: For the street you cannot go
past tri-Ys in a performance Commodore. They give a great sound and
really pick up the bottom end/midrange, meaning they require little if
any tuning. They are also extremely
well priced and have the advantage
of clearance over a 4-into-1 set-up,
which will hang far lower below the
floor plan of the vehicle.
SC: How restrictive are mufflers on an
exhaust system? Does running fewer
mufflers really help a vehicle perform
noticeably better?
PM: Removing mufflers gives nothing but a placebo effect on power
due to the added sound. Removing
the last muffler will simply increase
that annoying drone. If you want a
bit of added noise, you are better off
removing the centre muffler. Remove
the centre muffler and you will annoy
the neighbours. Remove the rear
muffler and it will only annoy you.
SC: Six-cylinder naturally aspirated
(worked)?
PM: Once again, for the street
2.5in would be the better option. You
could go for 3in if you really wanted,
but on the street it is probably not a
good idea as there would be a large
increase in drone.
SC: Six-cylinder turbocharged?
PM: As big as you can go. Fit the
largest system possible under the
floor plan of your car. Some 3in is the
absolute minimum, but 3.5in or 4in
preferred.
SC: Eight-cylinder?
PM: A twin 2.5in system is best for
the street. It will give a strong gain in
performance as well as keeping the
police off your tail because it won’t
be overly noisy.
SC: What are the benefits of using stainless steel during the manufacture of an
exhaust system?
PM: It’s all about longevity. A mildsteel system may only last 2–5 years
before deteriorating, while a stainless system has a far longer life once
fitted to the vehicle, and generally
lasting over 10 years.
That being said, we have removed
15-year-old Pacemaker headers from
vehicles that were still in perfect
working order.
It is important to understand
that different components from an
exhaust have different requirements.
For the manifold, stainless has an
increased chance of failure due to
cracking, as the part itself is very
close to the source of heat and stainless steel is a far harder substance
than mild steel. Mufflers, however,
benefit greatly from being made from
stainless because it is far more resistant to moisture, as do the pipes from
the cat back.
SC: When it comes to pipe size, what is
the general rule of thumb with regard to
the correct balance of backpressure and
gas flow on a street vehicle powered by a
naturally aspirated eight-cylinder (stock)?
PM: 2.5in single system, for a
good solid power gain without being
overly noisy.
R
HM HEADERS
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EXHAUST BUYER’S GUIDE
Just by looking at the internals of a straight-throughtype muffler, you can tell it is
going to flow a hell of a lot
more than an OEM item
Gutting your catalytic converter, as
you can see young Liam is attempting to do here, is not only illegal
but also highly destructive to the
environment.
We would advise Liam to go out
and buy a Metal Cat instead, which
will net the best of both worlds for
his vehicle
THE BROCK SHOP
www.thebrockshop.net.au
The Brock Shop offers everything from
simple muffler swaps, right through to
complete off the shelf or custom-made
exhaust systems. It stocks headers to suit
most Commodores, and can fabricate an
exhaust to your exact specifications.
The level of pride with which the team
approach their work brings pride to the
name upon the banner they ride beneath.
THE LONG ARM OF THE LAW
We sat down with John Varetimidis, RTA consultant engineer, and
discuss laws and engineering regulations regarding exhausts.
SC: What are the regulations regarding
the number of mufflers included in an
aftermarket exhaust system?
JV: You must run the same componentry featured in the standard system. That means the same number of
mufflers, resonators and a catalytic
converter if it had one.
SC: What are rules regarding exhaust
ground clearance?
JV: An exhaust must comply with
the same clearance regulations as
the rest of the vehicle, that being
100mm from the road’s surface laden
(meaning with people in the vehicle).
This equates to around 110–115mm
unladen, so be careful as many people get caught out on this.
SC: When fitting an aftermarket catalytic
converter, will any brand item be legal in
the eyes of the RTA/EPA/police?
JV: No, the catalytic converters
must comply with Australian standards, particularly 2006 and onward
systems, which must be either ADR
approved or developed through massive amounts of testing.
SC: Sometimes you go down to the local
exhaust shop and buy an off-the-shelf
system, come home and fit it up, only to
find it sticks out the back a fair bit further than the original did. What legalities
surround this?
JV: The exhaust system cannot
overhang past the permanent bodywork of the vehicle, but the issue is
nowhere near as serious as those
who cut the things off too short.
SC: When upgrading the size of the
piping in the exhaust, are there any
rules that must be adhered to? Or is it a
case of simply meeting noise/emissions
regulations?
JV: As long as the exhaust system
meets the required dB restrictions
and emissions requirements, then it
is fine in that aspect.
SC: What are the current noise requirements for passenger vehicles?
JV: For pre-1983 builds they must
be below 96dB, 1983–2005 plated vehicles must come in under 90dB and
2006 onwards vehicles must comply
with varying regulations depending
on a number of things including the
capacity of the engine.
There is extensive testing required
to make a custom exhaust legal on
these vehicles, and as such, it is a far
better option to simply get an ADRcompliant system off the shelf.
SC: Diff dumpers. Do any situations exist
whereupon they could be considered
legal?
JV: Absolutely not. The exhaust
must not exit underneath the vehicle
within the perimeter seal of the
bodywork.
SC: Can you detail for us some other
areas in which people fall short when it
comes to exhaust legalities?
JV: I’ve seen people running
exhausts within 10–15mm of fuel
systems and fuel lines, solid-mounted
exhaust systems, and systems that
knock around underneath the vehicle
like you wouldn’t believe.
The worst has to be idiots who cut
the things off at the diff, however.
This cut-out of a typical catalytic converter
gives you an idea regarding the density of
the element within the unit. Although cats
may take on a wide range of appearances
on the outside depending on brand and
model, a ceramic item will generally look
much like this internally
SUREFLO
www.surefloexhaust.com.au
Sureflo can supply headers from almost
any brand you could possibly imagine.
The company offers parts in stainless
steel or mild steel, and when it comes
to finishes, you can choose from HPC,
Zinc Passivate or heat-proof paint.
Sureflo is always at the forefront
of exhaust development, and one of
the first exhaust companies to get its
grubby mitts on a VE Commodore. Its
products’ quality is matched only by
the company’s dedication.
Straight-through mufflers
come in a variety of styles,
including this twin-type unit
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