Published in the January 2014 issue of “Die Porsche Kassette”
The ONLY way you can make more power in an internal combustion engine is to push more air through it, period.
You can do this by increasing the displacement (boring out the cylinders), by adding forced-air induction, such as with a Turbo or a Supercharger Kit, or by making your engine’s airflow more efficient.
But you can 'cheat' and use a loophole whereby you can reduce wasted energy (make more net power) by improving the exhaust side of things by adding headers.
Looking at the four stroke diagram you can see that the engine produces all its power during the power stroke.
The Intake, Compression and Exhaust strokes are required to make the power stroke possible but they drain power from the Power stroke.
In the Power stroke the gasoline and air mixture is ignited by the spark. It explodes and as the gasses expand, they push the piston back, thus generating power.
At the Exhaust stroke, back pressure is a certain way to lose power.
When the exhaust valves open at the beginning of the exhaust stroke, the piston pushes the gasses out of the cylinder and if there’s any resistance that these gasses have to overcome, such as back pressure, then power is wasted.
In a flat-6 Porsche engine, whether air or water cooled, the exhaust gases end up in the exhaust manifold.
From the manifold, the gases flow into one pipe, through the catalytic converter(s), through the muffler and its baffles, and finally out to the atmosphere.
At the exhaust manifold, one cylinder’s exhaust creates back pressure for the other two cylinders.
What makes the headers work is that they help to eliminate back pressure. Instead of having all three cylinders on one side of the engine share one common exhaust manifold, with headers, each cylinder gets it’s own exhaust pipe.
All three pipes come together into a larger pipe called the collector.
Each one of the three pipes is cut and bent so that they all have the same length as the other two.
By making them the same length, it guarantees that each cylinder's exhaust gases arrive in the collector spaced out equally so there is no back pressure generated by the cylinders sharing the collector. This reduces wasted energy.
But remember that if you want to make more power you’ll have to increase the air flow from the air filter all the way to the exhaust tips, and many times it requires replacing and/or improving the: air filter, intake tube, throttle body, intake manifold, exhaust manifold, catalytic converter(s) and muffler.
Finally, after you do all this you’ll need to remap the car’s computer so that it can all come together efficiently.
To learn more about headers and engine power please visit my website at: wwwPedrosGarage.com.
Ⓒ2013 Technolab / PedrosGarage.com