...i.e., when referring to that basic engine mod, the "intake/header/exhaust" job. My understanding is:

Intake: Usually a series of ducts and an air filter to transmit air from outside the car to the engine's intake manifold. Design considerations are low restriction and low air temperature.

Exhaust: Principally the exhaust tubing and mufflers, from cat back. Design considerations are weight, low restriction at high rpm, "proper" restriction at low rpm, and overall sound quality.

Header: Well, what's left? The intake manifold (only)? Or the exhaust manifold? Or the combination of the two? Design considerations would be, again, heat dissipation, air flow, and weight. Aside: Is the actual cylnder head ever implied here?

Thanks,
John

 

Slang term for exhaust manifold.

 

I thought that the headers were the "connecting pipes" between the exhaust manifold and the cat ??

I think exhast manifold and headers are not the same (I'm NO engine person, so please correct me if I''m wrong).

- Relson

 

"Header" and "exhaust manifold" are interchangeable terms...you remove the exhaust manifold, you have just removed the header.

 

Some cars, my old Integra GSR comes to mind, build the exhaust manifold in a few more sections. That engine has mini-separators right at the exhaust ports, "A-pipe" or "B-pipe" (loss of memory is tragic) is what Honda called 'em. Then the "header" attaches to that. I noticed a loss of high-end power and the dealer ended up replacing that section since the separators were breaking down.

 

When I was growing up I always thought of headers as a "tuned exhaust" with the implication being that more work went into maximizing performance. On our car the exhaust from the factory is pretty damned good so there is a little gain with aftermarket exhaust but not too much. Back in the 60's and 70's with musclecars (before my time) I believe there were much more gains to be had.

 

He is right. Header is slang for Exhaust Manafold. Comes from the exhaust manafold being attched or hung of the "head", slang first became "header-pipes" and then just "headers"

Bad thing about being and old fart is that I can remember when no one called them "headers". Growing up it was always "header-pipes"

 

talking about HEADERS,

I've always wondered where the name CAMshaft come from?? I mean, I can make sense of CRANKshaft, or PISTON, or VALVE..

but what the hell is the CAM- in CAMshaft??

 

"Cam" means rotating actuator. You see them often in industrial machinery to time one function off of another.

In an internal combustion engine the cam lobes are egg shaped rotating actuators cast in phase on a shaft (camshaft) which is driven by the crank shaft via belt, chain or gears. The cam lobes open and close the intake and exhaust valves with the help of little rockerarms.

 

Another implementation of a 'cam' is on Nautilus workout machines. That egg-shaped gizmo gave, and this was a criticism of the machine, the lifter an advantage when the lobe of the cam would roll around and help you lift the weight.