Is the exhaust manifold the same as the exhaust header?
The answer is no they are not the same thing. BUT they do perform the same FUNCTION. The function is that the reduce several exhausts ports into one exhaust pipe. I will use a V8 motor for an example. A V8 motor has 8 exhaust ports that are split between two cylinder heads. 4 exhaust ports each. One bank of four on each side of the motor. An exhaust manifold and an exhaust header also have four ports on the flange where they bolt up to the exhaust ports on the cylinder head. Here is how they differ. a manifold is exactly that-- a manifold meaning it is one hollow chamber that is cast with 4 flanged holes formed into the side of it and one large hole that is cast and flanged at one end on the bottom side of it. And the large hole is where the one pipe connects. So you would have on a V8 motor eight exhaust ports that dump into two exhast manifolds and travel through two pipes 1 on each side if it is a dual exhaust system that is . If it is a single exhaust system then the two pipes coming off of the manifolds are reduced further and joined together somewhere in the center of the car and both flow into one singular pipe. A header's function is to direct the exhaust from each port through an individual pipe and each pipe is joined at a collector box that is joined to one large diameter pipe that is short in length and is straight. These individual pipes are the same diameter as the ports that are on the heads and any changes in the flow are long sweeping curves that are smoooooth. So in effect what happens is you get an extended ehaust port length and no drop in pressure. in fact because there is no pressure drop, and you just made that exhaust port 4 feet longer you get even more pressure and when it finally does release in the collector box that extra pressure becomes propulsion. which reults in increased horsepower and performance. In fact I am confident that every header manufacturer will easily guarrantee an increase of 15 or 20 horsepower to any motor simply by just taking off the manifolds and putting headers in their place alone. With no other modifications whatsoever. That is a dramatic increase in power and its simple to do. I hope that answered your question. May the God of your choosing Bless you.