When you are browsing the Internet for cars you plan to buy
in the future or after you save money for a few more decades, you’ll come
across two common automotive terminologies: turbocharger and supercharger, unless
you plan to purchase an electric car in which case what you read will only be charger. Just by the names alone, it is
easy tell that a car with either supercharger or turbocharger is going to be a
lot faster than the same exact model without the additional component. Even in everyday
conversation which has nothing to do with automotive engineering, the words turbo and super indicate something superior. Superhero is more fictional than
just hero, superman is an alien, supercars are more expensive than cars, and
even Super Mario sounds a lot better than Mario. The same thing applies to
turbo with turbojet, turbofan, turbo-generator, and so on.
Cars, beside for the purpose of taking people from point A
to B, are also excellent for showing-off. This is one of the main reasons that
car manufacturers want to produce something faster than ever before and sell it
to people who can also afford personal drivers. They can also brag about the
fact that their cars are supercharged, turbocharged, or maybe both even when
they don’t know exactly how the components work; the not-so rich ones should be
content as long as their small slow green electric vehicles are simply charged.
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| Some cars are turbocharged or supercharged, or both; that one is just charged |
Even a typical combustion engine without those components is
already fast enough for most people. In real world circumstances and city roads,
you don’t actually need any turbocharger or supercharger to get a speeding
ticket or arrive on time at a costume party. However, having a ridiculous
amount of power at your disposal at any given moment is almost as exciting as
actually using it. Everybody loves redundancy – or more precisely things they
never use – and it is exactly the same thing with an abundance of horsepower in
a car.
Forced Induction
System
Both turbocharger and supercharger are forced-induction
systems. They compress air and force it to enter the engine. By compressing air
before it actually mixes with fuel, the engine does not need to make larger space
for more incoming oxygen. Typical forced-induction system can deliver 50% more air.
A small engine with either turbocharger or supercharger can match or even
surpass the power level of its normal counterpart. It also means more power
without sacrificing fuel efficiency. Although those components have the same
purpose, they deliver the extra air and power through different methods.
A turbocharger works
thanks to the expanding gas inside the engine’s exhaust. It has two turbines:
one is connected into the exhaust, and another into the air intake port. As the
engine develops power, the exhaust spins one turbine. When this turbine spins,
another follows suit and increases engine air intake. Such mechanism gives
double advantages. First, there is no direct mechanical load to the engine.
Turbocharger is powered solely by the still-expanding gas in the exhaust; it
does not require or consume power from the engine at all. Second, it improves
efficiency since the power that spins its turbines is basically residue to be
wasted as heat through the tailpipe anyway. Turbocharger transforms an
otherwise unused heat into more power.
Key disadvantage is something called turbo-lag. Since
turbocharger requires wasted energy,
you need to produce more of it to get more intense air intake. In other words,
you need higher RPM for the action to happen. At low RPM, the amount of backpressure
in the exhaust offsets the advantage of air intake increase.
On the other hand, a supercharger
is driven by the engine. It is connected to the engine with a belt, gear,
chain, shaft, and anything else except supernatural powers. A supercharger
spins its turbines because it gets power from the engine as well. However, the
increased air intake gives much more power boost than the energy required to
spin the turbines. This means a supercharger kicks-in even at low RPM. It does
introduce mechanical load to the engine, but there is turbo-lag issue.
To eliminate the disadvantages, some cars are both supercharged
and turbocharged at the same time, hence twin-charger. At low RPM, supercharger
does the job to deliver more air into the engine, but the task is soon taken
over by turbocharger as the engine develops enough RPM to offset the
backpressure in the exhaust. Also immediately the supercharger is decoupled and
bypassed to eliminate mechanical load. Some examples of cars that come with twin-charger
from factory are Volvo T6 and T8 models lineup, Volkswagen 1.4 TSI, Nissan
Super Turbo, Lancia Delta S4, and Zenvo ST1.
There is also another variant called electric
turbocharger, which takes advantage of both wasted energy in the exhaust
and electric compressor developed by Audi. As the name says, it is basically a
typical turbocharger but with the addition of energy recovery system to help
spin the turbines.
More Air is Better
The real mechanism of turbocharger and supercharger are
pretty complicated, but the point is that they deliver more air into fuel
combustion chambers. Increased volume of oxygen in the chambers allows the
engine to burn an increased amount of fuel and turns it into more horsepower.
Think of these chargers as superheroes suits that transform Bruce Wayne into
Batman or Tony Stark into Iron Man. Well, Batman does not actually fit to the
description because the man behind the bat-suit is already combat-ready anyway;
Iron Man does fit nicely, though.