Headers - educate me.

[cturok7]

What is the function of headers? I know they improve the airflow and I'm told they equalize the compression or something to that affect. Do they come in the stock setup? The reason I ask is because I'm doing the Balance Shaft Elimination soon and I might as well do some mods while I have the engine out.

 

[diablos991]

The 4g63t is equipped with a "header" (singular since the car is an i4) most often referred to as an Exhaust Manifold.

This item is the first part of the exhaust system located before the turbocharger on the 4g63t. The stock one is decent flowing for stock. However there are many other alternatives to help exhaust flow.

Replacing the exhaust manifold alone will not yield a large change in horsepower on a stock vehicle.

The upgrade path listed on this site is a fantastic reference when upgrading your car.

Here is a generic breakdown as to how an exhaust manifold functions.

 

[delta448]

Normally when you're referring to a turbocharged 4 cylinder, we use the singular term "exhaust manifold". "Headers" is a term more associated with a naturally aspirated engine with more than one bank of cylinders, usually american V8s.

I think you need to do a lot more reading and researching to help you decide what you want to do to your car before you start making decisions about performance parts. Please don't take any offense, but you can learn a lot from searching this site and others like the "How Stuff Works" site Shawn linked.

 

[TunaTalon]

With a normally aspirated engine the headers are designed/tuned to manage the pulses from individual cylinder firings in order to lower back pressure and maintain exhaust gas velocity. The inertia of exhaust gas maintains the flow and "scavenges" exhaust from the cylinders.

However, with turbo charged engines such as our 4G63T's the lower back pressure the better. The energy lost from the pressure drop across the turbo has a gain of about 7:1 in shaft horsepower.

With a normally aspirated engine, higher exhaust velocity gives better low end torque. With a turbo engine, higher exhaust velocity just means less gain from the turbo.

Boost is good.

 

[kmoore]

DSM's don't have headers

 

[oldman]

I like getting headers.

 

[ekips009]

a header is pretty much 4 pipes with a engineering feature for equal lenghts (thats why they are all bent and so on) so that supposedly you end up with all the exhaust gases hitting your turbo at the same time making it spool up at lower rpm's or for non turbo engines it decreses back pressure (like the others said)
Hope that helped

P.S. if any of this is out of place im sorry, as you can tell i just signed up and was just using my basic knowlege of cars not to savy with DSM's yet.... but thats what im hoping to do with this site.
Thanks

 

[oldman]

P.S. if any of this is out of place im sorry, as you can tell i just signed up and was just using my basic knowlege of cars not to savy with DSM's yet.... but thats what im hoping to do with this site.
Thanks

Welcome to Tuners, please use proper capitalization in tech sections.

a header is pretty much 4 pipes with a engineering feature for equal lenghts (thats why they are all bent and so on) so that supposedly you end up with all the exhaust gases hitting your turbo at the same time making it spool up at lower rpm's or for non turbo engines it decreses back pressure (like the others said)
Hope that helped

That is what we refer to as "tubular manifolds". Generally speaking, headers are for NA cars that consists of manifold, o2 housing and downpipe all built as one piece, although some people, like OBX on ebay, do call a "tubular manifold" headers, coming from the Honda world probably has a lot to do with it.

 

[xxraptor660xx]

I like getting headers.

Oldmen don't get headers.

 

[kmoore]

I like getting headers.

I bet you do

 

[jtmcinder]

Technically, there is no difference. In practice, the word "header" is reserved for exhaust manifolds that are tuned in some way, which usually means equal lengths and/or staged collectors (e.g., the fancy 4-2-1s for NA Hondas). There is nothing wrong with referring to a tubular exhaust manifold for a turbo car as a header. This isn't typical and some people with start a completely useless argument over it, however, so I wouldn't do it.

- Jtoby