by Pat Stevens
Although X-pipes are essential for race cars, adding this modification to a stock car can be a good idea for many reasons - increased power, fuel economy and less noise inside the vehicle. This type of aftermarket performance part is something you can either purchase or have custom-made for you by a good muffler shop. Installation is simple enough for the at-home pro, and the result will be well worth the effort.
The Evolution of the X-Pipe
To understand the importance of the X-pipe in relation to improved performance and power, you have to know about its roots. The X-pipe is really the offspring of the H-pipe design, which was first conceived in the 1960s by the major American car manufacturing companies at the time. Duel exhaust pipes for V-8-powered vehicles are very noisy, as there is no sound wave cancellation between the 2 separate four-cylinder engines and unconnected exhaust systems. Engineers were looking for a way to cut down on interior noise levels and improve the engine's power. They realized that running a balance tube between the two branches of exhaust pipe would work to broaden the torque curve (thus improving engine performance) and dissipate sound resonance in the exhaust system.
In the 1990s improved technological advancements made it possible to construct an exhaust pipe that, instead of connecting by means of a balance pipe at a severe 90-degree angle, could unify the two branches of pipe to create a flow of exhaust in one direction.
Now X-pipes are being manufactured for popular performance cars, usually off-road versions minus catalytic converters, but you can also find them in legal models fully equipped with proper emissions equipment. Performing an X-pipe mod is an option that you should consider.
Why X over H?
It has been proven time and again that the X-pipe design is more efficient than the H-pipe. Various tests have shown that for multiple cylinder engines the X-pipe outperforms H-pipe exhaust systems, especially as rpm increases, providing both better torque and power. Unified exhaust pipes work most efficiently with multiple cylinders because of the scavenging effect. With exhaust X-pipes the almost seamless connection between the two exhaust pipes allows sequential firing cylinders to salvage any spent exhaust gases from the combustion chamber more efficiently and creates more room in the cylinder for a fresh intake of undiluted fuel and air. When you have two exhaust pipes, as the velocity in one header tube increases, the pressure in the adjacent tube is lowered causing the exhaust to be sucked out of that cylinder. X-pipes are simply better at doing the job, especially at higher speeds.
Installing Exhaust X-Pipes
This is a simple mod that almost anyone can perform successfully. Most companies produce exhaust X-pipes that are simple bolt-ons that can be installed in less than an hour using the usual hand tools.
If you own a vehicle that doesn't have an X-pipe available, it is possible to have a custom X-pipe assembled for you. A muffler shop can construct it by taking an X-pipe union and bending up some exhaust tubing until it fits. If you decide to make your own exhaust X-pipe from scratch, so-to-speak, remember to place the X-pipe union as close to the rear of the vehicle as you can to increase the power.
A Brief How-To
To install exhaust X-pipes, first begin by positioning the passenger-side header pipe in place and tightening it before moving on to the next step. Make sure it is secure. Now, fit in the actual X-pipe along with the driver's side header pipe. Remember that the long leg of the X must go toward the front driver's side of the car. Now it's time to fit the pipes of the X into position and loosely attach them to the after-cat system. You might have to adjust how the after-cat is hanging for proper tailpipe positioning and tuck up the X-pipe square. On some vehicles the tranny crossmember has an exhaust hangar - if this is the case you can tack the hardware onto the pipes. Tighten the bolts and tack-weld the junctions at the X. Check everything one more time before removing the X-pipe and welding the full length of the junctions. The assembled unit now needs to be bolted back into position - simple as that.
All in all, with exhaust X-pipes torque and power will increase resulting in fast acceleration, improved fuel economy and a nice quiet ride. The difference is noticeable with the installation of X-pipes on a V-8 engine vehicle - interior noise is reduced considerably because you don't hear the firing impulses of 2 four-cylinder engines, but instead hear the noise of all 8 cylinders blasting out of both pipes at once.
About the Author
Written by Pat Stevens sponsored by http://www.autopartswarehouse.com. The Auto Parts Warehouse offers 24h sales support & free shipping for orders over $50. Also, you'll find BMW auto parts here. Please link to us when using this article.