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Introduction
four-stroke
engine
Performance
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Basic explanations for some aftermarket
parts & engine components.
BHP
This is a term that stands for
"Brake Horse-Power". Which is basically the amount of
horsepower present at the engine crank, and NOT at the rear
wheels which is usually much less.
COLD AIR INDUCTION KIT
This is a kit that attempts to
relocate the point where the air is sucked into the engine to a
"colder" place (like into the fender well for example)
for better performance. Cold air is more dense than hot air and
produces a more violent explosion for better horsepower. Careful
when choosing a cold air induction kit, some kits provide long
lengths of tubing that will actually restrict air flow more than
providing a benefit in performance.
AUTOMOBILE TESTS.
0-60 TEST
-This is a test that is basically the time it takes for a car to
reach 60 miles per hour from a standing start. IN THE PAST
(the early automobile era) at the time when speed tests
were beginning to take place, 60mph was the fastest a car could
go, so this test was actually how fast a car could reach it's
top speed! Today, the 60mph standard still stands, but cars
today are capable of much higher top speeds.
ENGINE DYNO
-This is a test machine that measures
horsepower and other data about your engine. Most performance
shops have a dyno so they can see how modifications affect the
performance of an engine. It uses a multitude of sensors
including a "rolling log" under the rear wheels, to
calculate data about your Car. People will say for example:
"I dyno'ed my stang at 250 rear wheel horsepower
man....". There is a difference between "rear
wheel" horse power and "crank" horsepower. Most
of the horsepower numbers that are published and reported, is
how much horsepower is present at the crank. Horsepower is lost
in the drivetrain. By the time it reaches your rear wheels
you've lost at least 15% .
FUEL PUMP
The Fuel Pump is an electrical
pump located inside your Car's gas tank that pumps fuel
through your car's fuel lines and then into your injectors.
Like a balloon has air pressure, the fuel pump must maintain a
minimum "fuel pressure" to ensure that your car's
engine gets enough fuel. Every time a fuel injector squirts
fuel, the fuel pressure is affected. Your fuel pump is always
running while your engine is running to always maintain a
constant fuel pressure. You can even hear the fuel pump when you
first start your car. That little "buzzzz" coming
from the back of your car when you put the key in and are
about to start is your fuel pump. Your car also has a remote
fuel pump cutoff switch that turns off the fuel pump in case of
a bad accident. Your electric fuel pump does not ignite the gas
in the tank (even though it's completely submerged in gas)
because an open spark or flame is required to ignite gasoline.
You can purchase high performance aftermarket fuel pumps that
replace your stock pump OR purchase an "in-line" fuel
pump that is placed just outside your gas tank, this means that
you have two fuel pumps pumping, your stock one AND the
aftermarket one. Aftermarket fuel pumps are required when you
start to heavily mod your car to ensure proper fuel delivery
and fuel pressure.
SUPERCHARGER
A supercharger is a unit
that "blows" air into your engine. It looks like a big
alternator. Like a vacuum cleaner an impeller (driven by your
crank) draws air into your engine. Normally, your engine would
have to "suck up" air as needed on it's own. Because a
supercharger "forces" air into your engine, your
engine creates more horsepower. A supercharger is another engine
accessory that is powered by the crank, like your alternator or
water pump is. A little HP is lost at the crank to drive the
supercharger, but the horsepower gained from the forced
induction more than compensates for this.
RAM AIR
When you are driving down
the road at 50MPH and you stick your hand out the window, you
can really feel the wind resistance blowing your hand backward.
What if you could take this air and RAM it into your intake?
Well, with the right tubing or hood you can do it. When your car
flies down the road, air is blown or "rammed"
into your intake, hence the name "RAM AIR". The only
problem is, a ram air system must be very direct. If air has to
travel through 4 ft. of tubing before it reaches your intake
then you'll have to be going 60MPH before you feel the benefits
of a RAM air.
TURBOCHARGER
A turbo is very similar to
a supercharger but a turbo is powered by your exhaust system. A
special header is fitted to your engine that blows exhaust gases
past an impeller and drives air through the turbo and into your
intake. Some problems with a turbo charger is that heat
generated by your exhaust, heats up the air that is forced into
your intake. Intercoolers were created to control this problem.
Also, because turbos are powered by your exhaust system, at low
RPM's you don't get the full benefit of the turbo, to get the
turbo spinning up to speed you need to really be
"flowing" exhaust gases through the turbo, which does
happen at higher RPM's. This is often referred to as "turbo
lag". The benefits of a turbo is getting high levels of
boost is no problem. A "twin turbo" is a car which has
a turbo blower fitted to both exhaust sides (in a V type
engine).
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