NOLAN5162

What are the advantages and disadvantages to running headers?

Obviously it effects how the turbo bolts up.

Does the turbo because less efficient from being farther away from the manifold? or does that matter at all?


Thanks

StevenH

The only real reason to change the exhaust manifold on our car would be to use one that is compatible with a new turbo. If you are using a k03 or k04 the stock one is fine and can be ported if you want to flow a little more air.

NOLAN5162

isn't it a "flow" thing?

A400

Only low power cars dont need headers, above a certain level custom headers are only option, but this is well over 400whp, but the blanket statement is not correct
Rod

AntiSocial

Lots of turbo cars use headers, but it's all semantics. When you say "header", most people think of N/A applications. There are plenty of aftermarket headers available, including Innovative Turbo, ATP, etc.

Porting a stock header is probably a bad idea since you are reducing the physical mass of the header, thus not allowing maximum absorption of heat, leading to fatigue failure. Plus, you're not really getting any improvement in flow by marginally improving runner radius.

NOLAN5162

damn..THAT informative...thanks..in your opinion, is there gains putting a header on a 1.8t?

StevenH

I guess you could call a tubular exhaust manifold headers though.

AntiSocial

<center><img src="http://pictureposter.audiworld.com/32851/headers4.jpg"></center><p>
<ul><li><a href="https://forums.audiworld.com/performance/msgs/54235.phtml">.</a></li></ul>

fusilier

Even if it is cast or tubular. Its usually called an exhaust manifold by those in the know.

the term "Headers" is typically used for normally aspirated cars.

To answer you questions.
The turbo isn't necessarily less effecient. The length of the piping in the manifold is ideal at a certain distance where the individual puffs of gass coming from the exhaust valves arrive at the plenum in the exhaust manifold in sequence so that the turbo is seeing a more uniform and consistent delivery of driving exhaust gases. A good tubular manifold will also direct those exhaust gases onto the vanes of the turbine to aide in spooling. Some gas acceleration may be designed in as well.

Overly complicated bends in the pipes could be considered bad since that means more loss in energy as the gases make those bends.

Here's a lehmann exhaust manifold for a 20V audi 5. This header is good for making 500 hp. It uses Porsche 911 turbo flanges. So you see it has high flow, high strenght, custom flanges for larger turbos and wastegates. A unified plenum to channel the gases right into the turbine. Extra length added to the 2,3,4 cylinders to have uniformly spaced gas arrival times. A great design.

<img src="http://pictureposter.audiworld.com/38899/lehmannheader.2.jpg">

Stratocaster1422

A header is any equal length piping setup...whether turbo or N/A. Look at AntiBenz's pic there...