A typical stock exhaust system is made up of the exhaust manifold, catalytic
converter, muffler, and various lengths of piping to connect them all. The
problem with stock exhausts is that they're designed for just about everything
except performance: the good folks at the car companies design their exhaust
systems to conform to be as quiet, environmentally friendly, and inexpensive as
possible. While I'm all for peace and quiet and blue skies and all that, there's
nothing I like more than that awesome sound of a great
performance exhaust system.
When it comes to performance exhaust, we want big pipes with as few restrictions as possible in order to avoid backpressure. Think of blowing hard through a drinking straw versus through a 2" pipe--big difference! Backpressure robs your engine of power because instead of directing energy at the crankshaft, your engine has to push the exhaust out under pressure. Some backpressure is inevitable, but there's a lot you can do to a stock exhaust system to minimize it. Today,we are going to take a look at replacing the exhaust manifold with a performance header.
Headers are purely performance-based upgrades. Not only are their pipes bigger than stock, but each cylinder gets its own specially tuned pipe. Tuned pipes? Yep! The lengths, curves, and inside diameters of header pipes are specially designed to follow the rhythm of your engine's exhaust valves so that every time a cylinder expels air, an empty header pipe awaits. So, there's very little backpressure for the pistons to work against.
If you've been surfing through the Internet stores, you've noticed that there are a lot of different exhaust headers for sale. They boil down to two main types--stainless steel and ceramic-coated. Stainless steel headers provide a smooth surface for the quickest possible airflow. They usually are shiny when new, but don't expect that to last! Ceramic-coated headers are usually stainless steel or cast-iron headers that have been coated with a heat-resistant coating that keeps your engine bay a bit cooler. You'll also notice that most headers have a design in which the four exhaust pipes join into two bigger pipes, and then the two join into one final pipe that connects to the rest of your exhaust system. This "4-2-1" design is pretty standard, and most of these headers will be street-legal. Most headers that have a single "4 into 1" collector are designed for full-on racing and are likely not emission-legal.
Like the exhaust manifold, the header bolts right up to the engine block using the same bolts. If your exhaust bolts are really rusted, you might want to find replacements for them at an auto parts dealer or hardware store--headers almost never come with their own bolts. While you're at the auto parts store, you should also be sure to pick up a new exhaust gasket. You can expect to see a gain of about 3 to 4 horsepower right out of the box. Of course, if you replace the full exhaust system, you can expect another 2 to 4 horsepower.
An exhaust header is another one of those simple, do-it-yourself ways to bolt on horsepower. Once you've helped your engine breathe more freely, you'll be eager to take a look at other aftermarket performance parts.
This article was provided by: http://www.qualitycustomparts.com