"PIPES
of PACE"
YES WE
CAN
Slipping on an end-can must be the easiest tuning mod ever. The promise of
more power, good looks and reduced weight makes it the most popular as well.
Changing the end-can on a typical bike takes 15 minutes max. A small time
to spend if you're going to get an instant power hike. If you've not got one
fitted already you've certainly thought about it.
Their popularity is reflected by the bewildering choice on offer, with over
40 manufacturers offering end-cans in, usually, carbon fibre, titanium, aluminium
or stainless steel. It's a big market alright, industry estimates say that
one in five bikes has been fitted with an aftermarket end-can. Several companies
make silencers to order, and customers can have them colour-matched to their
bike's paint scheme.
Given that the manufacturers get everything so right these days, it's hard
to imagine that any real performance benefit can be had from an end-can swap,
suggesting that the 20% of road bikes already sporting race-cans make more
noise and not a lot else. But standard cans are de-signed to meet noise and
emissions regs, so they're often restrictive, heavy and cumbersome. And you
never see a race bike without a can fitted - teams like Castrol Honda and
Virgin Yamaha don't fit big name race-cans just because they look and sound
nice.
The only reliable way to prove that a particular race-can gives more power
over the stock can is on a dyno. Gains, where there are gains, usually feel
so small that it's hard to tell just by riding if the bike is any faster.
Noise increases are often much greater. Race-cans are typically three to four
times louder than originals, taking them well over the legal noise limit.
Whether this is desirable or not is down to personal preference. We know which
ours is.
Another aspect to consider is fuelling - race cans claim to improve power
output by improving gas flow, which can in turn affect the air/fuel ratio
[AFR]. Many race-cans claim not to mess up the AFR. But when the risks of
incorrect fuelling include engine damage like holed pistons from very weak
fuel mixtures, simply taking someone else's word for it won't do.
When you consider all the factors in fitting a race-can a little help is needed,
end-cans might be simple to change but how easy are they to live with? Do
they liberate extra power? Will they wreck your motor? We decided it was rime
to find which slip-on race-can is just what the doctor ordered to free up
your waste gases and loosen everyone else's ear-wax.
CAN THE
CAN?
The majority
of people fit race end-cans because they want more power, slipping them on
first thing Sunday morning, then giving it the beans down the bypass hoping
to feel more corruption kicking out of the back wheel. We've included the
2001 FireBlade (the bike used for this test) standard can's trace on each
graph so any losses or gains are visible.
To obtain the figures we used Dynospeed Development's load cell Dynojet dyno.
Using fourth gear roll-on figures we were able to see if any extra power was
made not only at the peak but at any point in the rev range. Each can had
a total of four runs, two with standard fuel settings and two with new fuel
maps courtesy of a Dynojet Power Commander III plugged into the bike's ECU.
The first run of each pair was to stabilise temperature, the second to obtain
the figures.
Power gains are not the only things Sunday morning tuners expect from their
new purchase.
There's less weight for a start. Only the latest bikes like the FireBlade
have lightweight end-cans. Steel cans on older bikes weigh almost twice as
much. Swapping the standard can for a race item could save up to 5kg, meaning
you can hang fire on that diet a while longer.
Then there's build quality. Although beauty is in the eye of the beholder,
you've got admit a shiny new titanium or carbon can as used in the upper echelons
of the racing world looks the dog's cods. But we gave them a good going over
to see if any had the build quality of Fido's plums too.
Noise is the next issue. Race cans don't need to pass the EC drive-by test
like a standard end can and they are much louder. But they must pass the ACU
noise limits for racing or trackday use.
We tested all the cans according to the 2001 ACU rules, which dictate a maximum
of 105dB.
Then there's fuelling. The Blade had an air/fuel ratio probe stuck up its
flue during every dyno run. This enabled us to measure how far out each can
sent the standard fuel injection settings. Then we plugged a Dynojet Power
Commander III into the Honda and tweaked the fuelling map for each can.
The resulting power curves are the ones shown on the top 20 end-cans. It should
be noted with a little more time the individual maps might have yielded even
better results through subtle tweaking.
OPENING
THE CAN.
With
the exception of the standard Honda can and to the extent the Micron Shockwaver,
all race cans use the simple method of sound absorption to silence the noise-in
exhaust gases. A simple piece of perforated tube is encased in glassfibre
[rockwool] and as the exhaust gases pass through the tube the can's 'packing'
absorbs a centage of the sound energy.
The advantage of the
absorption-type silencer is simplicity of construction. This makes them light
and non-restrictive increasing power output.
Their main disadvantage is an inability to curb the frequencies that make
the most noise.
Most engines produce several frequencies of noise that contain much more energy
than the rest. That's why when a bike is fit-ted with a race-can it has a
deep burble at low revs and a high pitched scream further up.
MATERIALS
WORLD.
Exotic, lightweight
materials that were once the preserve of American spy-planes and F1 cars,
can now be found in grandad's Zimmer frame and stuck to every other Max Power
reader's dashboard.
Of course a much better use for these materials would be to make things for
bikes. Things like end-cans. If your bike has a heavy stone-age end-can, a
beautiful, feather-light race item could shave pounds off your bike.
ALUMINIUM ALLOY
Hardly space-age, many of the latest bikes use aluminium alloy for their end-cans
as standard, offering a substantial weight saving over steel. Although about
a third of the weight of steel, it has only a third of the strength. And aluminium
corrodes quickly on salted winter roads. All the alloy cans we tested had
been anodised, giving them protection against this. Aluminium alloys are able
to withstand the heat and force on the outer skin but would fail if used for
internal pipework.
CARBON FIBRE
Stiffer than a tramp's sock, and even more lightweight than Ally McBeal on
a diet, the three lightest cans on test all had carbon fibre outer skins,
which
says something about A number of early can from severe heat degradation. Carbon
fibre is stable' 200°C and some were this limit by a combine and sunlight.
This made the resin that binds the carbon together turn brittle. Cans were
rendered so weak they could be crushed with a good squeeze.
Modern carbon fibre cans should be fine, as most incorporate a heat-proof
lining to protect the carbon outer. Carbon fibre can also absorb sound energy,
where metal outer skins tend to vibrate in sympathy to sound waves.
TITANIUM
Anything made from titanium usually has a sticker on it saying so, suggesting
it's a bit special. With strength equal to steel and half the weight, only
titanium’s high price limits its use. The BOS can even had the grade of titanium used stamped on it, grade 2 [grade 1 is weakest, 5 the strongest].
Some coloured titanium cans are anodised [multi-coloured] while others are
just heated to give bluing at one end. Excellent resistance to corrosion and
heat make it the ideal choicó for silencer internals as well.
THE LAW
Using
a race-can on the road is illegal. If you do get stopped by the fuzz, either
because he heard you coming or for some other misdemeanour, the consequences
for using a can vary greatly.
The most likely course of action the police will take is a rectification certificate.
If you're issued with one of these you've got seven days to put a legal can
back on and get an authorised MoT inspector to mark your certificate. However
under the Construction and Use regulations the maximum fine for using a race-can
is $1600.
To comply with the law the end-can must pass the noise test set by the EU,
this involves riding a bike fitted with the appropriate can past a microphone
at approximately 50 mph. Anything over 80dB and the can does not receive the
EU or BS AU 193 stamp of approval. No race-cans get close to this level of
silencing and have no such stamp.
Dealers can only offer for sale race cans that are indelibly marked 'not for
road use' or 'race use only' if he sells a race-can without these markings
he is then breaking the law.
One final word of warning -removing 'not for road use' and stamping in BSAU
193 or some other road-legal marking can land you in even deeper, hotter water.
People have already been convicted of perverting the course of justice for
doing this.
Pictures and Graphs.
CONCLUSION
If
you've just had a quick scan through this test and come to this conclusion
column wanting to know which race-can to buy others as the quick guide shows.
Only the original Honda end-can stands out as something special, cutting the
noise level down to a quarter of the volume of any race-can, weighing only
3kg and performing within four per cent of the best race-can's power output.
From these points of view it's hard to justify spending money to replace it.
That only applies to the Honda though, some bikes respond far better to an
end-can change, some even less. If you want to improve your bike do some research,
find out who specialises in tuning your model of bike, as they're all different
and respond to race-cans in different ways.
We found with the Blade the best way to improve power was to accurately map
the injection system, and the fact that all the race-cans on test adversely
affected the fuelling led us to this conclusion - if you fit a end-can then
you should also expect it to fix the fuelling.
If you only want to make some noise or gain a little top end power and don't
care about rough running at lower revs then you can see from this test almost
any race-can will do.
Some cost more and carry brand-name cachet. But spending the extra wedge to
get the make of end-can the top race teams use does not After all, they've
done considerably more to their bikes than simply fitting a race-can. And
noisy or not, you wouldn't want to ride them on the road -except for, that
is, a very open, unpoliced road
