Turbochargers.
Big or small, we love them all.
Let's give a big shout out to the Swiss, not only for their fine chocolate but also for
giving us Alfred Buchi.
Because of the Swiss engineer, turbochargers have been increasing horsepower since 1905
and since their invention, they have become one of the most popular methods of forced
induction available, adding more air and more fuel to your engine is a sure fire way to
increase the horsepower output, whether it is on land, at sea, or in the air, most gasoline
engines, even two-stroke, and rotary engines, can benefit from turbocharging.
Before the invention of turbos and forced induction, options to increase your engine's
horsepower were pretty limited.
Sure, you could increase the displacement of your engine by adding more cylinders or
even increasing the size of your current cylinders, but this can be complicated and very expensive.
Adding a turbo, on the other hand, is a much simpler and easier way to accomplish similar
or even better results.
Turbochargers effectively increase an engine's output by forcing more air into the cylinders.
Typically a turbo provides 6-8 PSI a boost but depending on the application it can add
as much as 50 PSI or more of tire shredding boost.
When you are at sea level, normal atmospheric pressure is 14.7 PSI, so by boosting the intake
charge by 6-8 PSI, you are essentially putting about 50% more air into your engine, which
in theory, should net you around a 50% increase in power right?
Well not quite.
Unfortunately, due to a number of factors like heat, friction, exhaust restriction,
and a little property called inertia, the turbo isn't 100% efficient.
So a more realistic expectation would be 30 to maybe even a 40% increase in power, depending
on your particular setup.
Let's take a closer work at the inner workings of a turbo and some of the components that
are involved.
Turbocharging is really quite simple.
You attach a turbo to the exhaust manifold or header on your engine and then you use
the exhaust gasses that would normally just go out the tailpipe to spin a turbine at insanely
high speeds, sometimes nearly 150,000 RPMs.
But the turbine itself only makes up one side of the turbo.
The turbine is directly connected tot he compressor side by a common shaft.
The compressor side is where we get the boost and works by pulling fresh air through the
air filter and into the center of the rotating blades.
Spinning at a high velocity, the rotational forces of the blades force the air outward,
compressing it and converting the high velocity, low-pressure air stream into a high-pressure
low-velocity air stream through a process known as diffusion.
Compressing the intake charge allows your engine to squeeze more air into each cylinder,
more air means that we can add more fuel, thus creating more power with each compression
stroke.
All of this without having to increase the engine's displacement.
Turbos are a great way to increase power on fuel injected engines but they can also be
used with carbureted setups as well.
With a carburetor, you have a few options.
You can install a specialized blow through carburetor on your intake along with a carb
hat, or you can install a standard carburetor, mount it before the turbo, and draw the air
through it.
The third option is to use a standard carburetor, mount it inside a sealed box, which is then
bolted to the intake, and pressurized by the turbo.
Unfortunately, like most things, power doesn't come free.
Anytime air is compressed it creates heat and as the air is heated, it expands, leaving
you with less air, or more importantly, with less oxygen molecules in the same amount of
space.
A small portion of the pressure increase that a turbo provides can be attributed to this
heating of the incoming air.
The end goal is to increase the power of the engine by getting more oxygen molecules into
the cylinder, not necessarily more pressure.
This is the primary reason why we use intercoolers.
They work similarly to a radiator with the exception that they pass air through the inside
to be cooled rather than water.
The intercooler can increase your power gains by cooling the warmer, pressurized air coming
from the compressor before it makes its way into your engine.
The intercooler provides a cooler, denser air charge that contains more oxygen molecules
than the warmer air does.
There are a number of factors that you should consider before you purchase a turbo, like
"do I have enough room in my engine bay?".
A lot of modern vehicles lack adequate space under the hood for a turbo and with the majority
of today's parts being made from plastic, there can be a serious meltdown and fire risk.
A great alternative is to use mid, or even rear-mounted turbos from companies like STS.
The turbos can be installed near the rear of your vehicle, freeing up space and also
offering some added cooling benefits as well.
Yes, size does matter.
Both under turboing and over turboing can create headaches like turbo lag, over boost,
and compressor surge.
A popular rule of thumb is to pick a turbo with the smallest wheel diameter possible
that still allows you to reach your horsepower goals.
I won't bore you with all the math that's involved in determining ideal AR ratios but
if you are considering purchasing a turbo, it's a good idea to speak to a reputable turbo
company first.
Provide them with all the information possible about your particular setup so that they can
recommend the best turbo for your application.
They can also help you size the correct wastegate to prevent over boost and suggest a blow-off
valve to prevent compressor damage.
Selecting a turbo is a lot like life, the more educated you are, the better off you
are going to be.
For more information on our full line of STS turbos or to get a recommendation for your
ride, visit our website at STSturbochargers.com