There's been a lot of discussion lately about larger diameter exhaust and open
air filters. By going to a larger diameter exhaust you decrease the effective
legnth of the exhaust. This raises the engine where produces peak torque, since
horsepower is a function of torque you do gain horsepower, but not torque.
Effective you have lowered the torque output at lower rpm, but raised it at higher
rpms. The same holds true for getting rid of the ducting connected to the air
cleaner. This length of ducting is figured into the tuning of the air intake.
Both the intake and the exhaust are tuned using helmotz tuning theorys, these
equations can be used to tune your intake and exhaust length to where you want
the engine to produce maxium torque. The length has to do with the reversion
pulses that are produced in both the intake and the exhaust from the valve
overlap. At the tuning peak the waves are cancel out. There is a web site
that has those equations so you just input your varibles and it will give you a
length. I plan on making headers this summer using the helmotz theory.
Contary to the common belief much time and money is spent in design and
development of all vehicle system to make them the highest quality.
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