A performance intake system consists of a free-flowing filter
element and a larger-than stock tube. It's Primary purpose
is to allow more incoming fresh air to reach the combustion
chambers at a higher velocity. The specially designed filters
restrict the engine from sucking up dirt particles. They sound
good too. (baaaaaawwp)
Headers are designed to expel the exhaust gases as efficiently
as possible. The positioning, size, and length of the primary
tubes determine the flow characteristics of the spent gases.
A 4-2-1 headeroffers greater low-end torque over a 4-1 header,
but the 4-2-1 lacks the high end characteristics of 4-1.
Aftermarket exhausts feature a free-flowing muffler with larger
diameter piping. The piping is also mandrel-bent, which means
that the diameter of the piping is maintained throughout the
bends. Remember Rawle told you an exhaust system is as efficient
as its norrowest point. Got That
. This greatly improves
the flow of the exiting exhaust gases and raises the noise
coming out of the muffler.
The ignition system should only be upgraded if you have turbocharged
your car or you're using nitrous. When the cylinder pressure
is increased and more air and fuel are dumped into the combustion
chambers, a greater spark is needed. Otherwise the factory
ignition is capable of providing the necessary spark to ignite
the air/fuel mixture.
An overbored throttle body increases the throttle response
and the amount of air drawn into the intake. With this modification,
horsepower is increased throughout the entire rpm band. In
order to realize the performance potential of the throttle
body, you must have the intake manifold match-ported.
It's a known fact that combustion engines will run more efficiently
at cooler temperatures. Turbocharged vehicles always run at
higher temperatures than naturally.phpirated vehicles, so
intercoolers are used to cool down the air intake charge.
With a colder, denser intake charge, more power can be realized.
Nitrous can give any type of vehicle instantaneous horsepower.
The extra oxygen molecules in nitrous oxide actually enhance
the burning of the fuel. Also, when nitrous oxide is injected
into the engine, it must absorb a large amount of heat in
order to transform into a vapor. That drastic change in temperature
causes the intake charge to become denser, which in turn packs
more of the air/fuel mixture into the combustion chamber,
resulting in more power.
Cams can be reground to change the lift and duration of the
lobes. You can go mild or wild when choosing cam specs. Selecting
a wild cam usually means that the idle is going to be rough.
A mild cam will idle, but it lacks the high-end pull of a
Cam sprockets are definitely worth the money because you can
control the intake and exhaust events. Any combination of
advancing and retarding will change the power curve. The general
rule of thumb is that by advancing the intake cam, you can
increase low-end horsepower. Retarding the exhaust cam will
increase high-end horsepower.
A turbo can be sized small to kick-in at low rpm, but it will
lack the high -end of a larger turbo. The trick to sizing
a turbo is to know exactly what type of performance you're
looking for. A turbo designed for the dragstrip will perform
well at the track but not on the street.
check out our Glossary of Terms
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