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at first blush. Headers, afterall, are found on N/A and SUPERcharged cars as well...
But the general concept can apply to turbo's as well.
A header is designed to "scavenge" the cylinder. In other words, each pulse of exhaust will have a siphoning effect on the next successive pulse, pulling the exhaust out of the cylinder, and the fuel/air charge into the cylinder during valve overlap.
Each tube needs to be the same length as the next in order to have any effect. A break in the tube will negate the siphon (actually scavenge...) affect. Headers generally are "tuned" to a specific engine displacement and RPM for maximum effect.
(Model airplanes use "tuned pipes" on their single cylinder engines. Effectively a combination muffler and header all in one piece)
So, as a rule, a header *sucks* the fuel/air charge into the cylinder, where-as a turbo (with no other mechanism such as a header) *blows* the fuel/air charge into the cylinder.
Combine a properly tuned, equal length header with a turbo... NOW you've got something!
APR makes a header for the Audi 1.8T tuner out there. That and a chip can get you ~400HP from 1.8 liters!!! AND they have a tranny that can take that abuse!
There are other combinations out there as well. Turbo's with Superchargers, Superchargers with headers have been around forever. Twin turbo's with differing trim's for both low and high end power. The fun never ends!
Hope that helps! For more reading on the subject, follow "Street's" advice, and pick up some books at your local library. Two in particular for Turbo's are: "Turbochargers" by Hugh MacInnes, and "Maximum Boost" by Corky Bell.
Good luck!
Jim M.
'97 900SE Turbo Coupe, Talladega Edition, Saab Sport Exhaust, Abbott Racing ECU, Abbott Racing Waste Gate actuator, Forge BPV, AutoMeter Boost/Vac gauge, Abbott Racing lowering springs, Abbott Racing Viggen Rescue Kit, SAS rear anti-sway bar, Zimmerman cross drilled rotors, Viggen Intercooler.
'88 SPG, modified APC, modified turbo solenoid valve, Viggen BPV
'02 9-5 Aero SportWagon.
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