But what are headers???

 

tube steel exhaust manifolds

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ICON Motorsports

1st & 3rd

 

I know someone can probably answer this better than i can, but here are the basics.
Headers are part of the exhaust system, usually installed aftermarket, that collect the exhaust separately from each cylinder. They take the place of an exhaust manifold which collects all of the exhaust from the cylinders at the same time. Headers help increase exhaust gas velocity, I believe, if used correctly and help make gains in torque and horsepower. hope this helps.


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ice

 

RS,

Ed and Ice got you the basics. Since I'm not afraid to ramble aimlessly, I'll take a stab.

Exhaust headers are set of steel tube exhaust manifolds, as Ed mentioned. They can help produce more power AND fuel mileage, as Ice points out.

They are generally individual tubes (one for each cylinder's exhaust port) that are collected at a point well behind the cylinder heads. The original intent of headers is to have a set of equal length tubes that have a tube size large enough to prevent restriction to exhaust gas flow, AND are tuned to a specified diameter (free area) and length to take advantage of the exhaust pulses and sonic pulse wave physics to help scavenge all the exhaust gasses out of a cylinder. The exhaust gas scavenging actually helps pull in some fresh air/fuel mixture in the process.

The tube length is tuned to produce the greatest effect at a given RPM. The theory is identical to the tuned induction principle used for TPI intakes, but on the exhaust side of the engine.

Typical factory cast iron or welded steel exhaust manifolds collect all the exhaust gasses and converge them almost immediately, with little regard to length tuning or undersized passages.

As I stated earlier, that is the original intent of headers. Practice doesn't always follow sound theory. It's almost funny to see someone with a TPI induction system and mismatched short-tube headers on the same engine. Or a "high-revving" engine with a short, straight-runner intake and carburetor and a set of long-tube headers on the same engine. One system is tuned for low RPM flow, and the other for higher RPM flow. The only benefit of the headers in this case is the larger tubes reducing the restriction in the system, but there is almost no scavenging advantage. Makes you wonder how they picked the cam profile...

Headers aren't the "perfect" exhaust system basis. They generally produce their own particular set of problems, like heat excessive loss and heat radiation in the engine compartment, more noise, and less durability. There are ways to combat the negatives associated with headers, just like there are ways around most other problems caused by engine modifications.

Oh, and if you were asking about machine tools instead of engine parts, a header is a reciprocating press that forges a screw or bolt into it's basic shape from a piece of wire or bar stock. They make even more noise than exhaust headers.

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Later,
Vader
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"Keep rollin' rollin' rollin' rollin'..."
Adobe Acrobat Reader 4.0
KaleCo Auto Parts

 

Here's a decent picture of what they have been talking about.

-Mark W.
'88 SC Camaro w/ 305 TBI

[This message has been edited by Mark305TBI (edited January 26, 2001).]

 

A picture is worth 1000 words... well on that note, I took Vader's text, and came up with 413 words (the one and only good use for Microcrap Word). Mark gets 1000 for the pic.

Mark wins.

 

Max,

I'll second that - almost. WordPerfect does a whole lot more, and counts words, too. It can even take the giant step backward and save files in MS Word format. (Yuck!)

Adobe has even more power, but is pricey. Oops! Guess I'm drifting off automotive "tech", but WP does "header" too, as well as footers. (And margins, and borders, etc. - just not valve margins.)


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Later,
Vader
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"Keep rollin' rollin' rollin' rollin'..."
Adobe Acrobat Reader 4.0
KaleCo Auto Parts

[This message has been edited by Vader (edited January 26, 2001).]

 

damn don't i get something for saving on server space?

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ICON Motorsports

1st & 3rd