Originally posted by PoohBoi
Exhaust manifold is a PART of the header right?
Header is the Whole Thing, leading from the Engine's Exhaust outlet to the Front Pipe just before the Catalytic Converter. and that Upper Part of the header, having 4 pipes connected to one end is called the Exhaust manifold.
And do you see your car's header if you open the Cover? Yes because that part is the Manifold OF the HEADER, you can't see the WHOLE HEADER, but at least part of it.
not exactly... a manifold and a header are two different things. yes they serve basically the same purpose, but the header is less restrictive.
a manifold has a signifigant amount of backpressure because exhaust gases from one cylinder build up pressure in the manifold that affects the next cylinder that uses the manifold. basically all the cylinders dump into a common pipe. the gasses from the exhaust stroke from each cylinder are not evenly spaced in a manifold. this causes the exhaust stroke from each cylinder to interfere with the next.
in a header the pipes are bent and approximately the same length to keep the exhaust stroke from one cylinder from affecting another therefore eliminating a signifigant amount of back pressure.
backpressure robs your engine of power because the piston has to push harder on the exhaust stroke to eject the exhaust gasses. this is why we try to eliminate backpressure as best we can with headers and other, more freely flowing exhaust components.