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For some high performance car tuners, one of the biggest dilemmas is the size of the exhaust
system. The exhaust simply put is the exhale of the engine that is a very important step in the combustion process. Each person
has their own belief in this area, but there are facts. The facts are easy to understand, but they are not very well known,
there are many wives tales about how back pressure is good, making big exhaust bad, but to small of exhaust is like a plug.
Is there a happy medium? Or is there an obvious answer?
The first myth of an exhaust system is back pressure is needed
for the engine to run right back pressure being the reverse positive pressure wave that comes back up the exhaust towards
the engine. Many people think that back pressure is lost the bigger in pipe size you go. However this is only half true, a
very small amount of back pressure is needed only to prevent some of the fresh intake charge from exiting the combustion chamber
before the exhaust valve closes. The first theory is that released back pressure provides more horsepower, this is true, however
you can not just run no exhaust and expect to gain thirty horsepower over stock. There are several problems with this setup,
one being the level of sound under any R.P.M. (revolution per minute) of the motor, another is smog issues, if your car was
made after 1980, you must get emissions tested, this is a procedure that protects our environment for future generations.
Another problem with the no exhaust setup is the lack of speed that the exhaust maintains, you need to get the exhaust fumes
out fast to make good power from your exhaust system. When you put tubing on an open exhaust system, it speeds the fumes up
(to a point a.k.a. the perfect size exhaust)
If you lose all of your exhaust system (i.e. removing the exhaust system)
you will not lose any torque, you will just move its peak up in the R.P.M. (revolutions per minute) range, making low end
(low rpms) go down, however, the upper rpms gain more torque, making your top end more powerful.
There are pros and cons
to each myth however there is one solution: the perfect exhaust system for your specific engine. Almost every vehicle can
benefit from an aftermarket exhaust system, each company has tested each application to make sure that their system delivered
more horsepower than stock. However if you had the abilities, you could fabricate and test a custom system, most all of the
companies tested their systems on stock (unmodified) or mostly stock vehicles, not taking into account extensive modifications
performed to the engine to produce more horsepower.
All in all, exhaust is not that complicated of a concept, there are
facts and there are myths, each person has their own ideas when it comes to gaining horsepower with exhaust systems. It is
not simple to find the perfect size of exhaust size for a modified engine, you can read tech articles from people who have
already done it and do your own testing. But for mildly modified engines, a regular aftermarket exhaust is perfect and will
give a noticeable increase in horsepower.
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