Instead, a typical four-cylinder engine at 8, rpm spits out more than 67 exhaust pulses per second, per cylinder, complicating and muddling up the whole process.
Primary tubes span from the cylinder head to a collector where exhaust gases from each cylinder join before entering the remainder of the exhaust system.
Like the intake side, air velocity is important, except here its own energy must be harnessed to evacuate the cylinders. Instead of doing all of this by means of positive pressure like the intake side, negative pressure generated near the exhaust valves helps suck unwanted exhaust gases from the cylinders. The hard part is figuring out a way to not just increase that negative pressure but to control it so that it occurs within the exhaust ports at exactly the right time.
Compared to log manifolds, headers can make more power in three ways, one of which is wave resonance tuning. Once the exhaust valves open, a high-pressure stream of exhaust gases forced out by the upward-moving piston begins exiting the cylinder head, creating a pressure pulse.
Once that pulse reaches the end of a particular primary tube, a reverse wave travels back up, creating a low-pressure void near the exhaust valves. The process is known as scavenging. You knew all of that, but you might not know why. Tuned primary tube lengths can help snake-charm additional exhaust gases out of the engine during each exhaust stroke.
To be sure, wave resonance and pulse tuning are the real keys to whether or not a header makes more power. Headers, on the other hand, have longer, individual tubes. To avoid the cracking issue, exhaust manifolds typically have to be made with thicker walls than the headers.
This shrinks the space gases can travel through. Combine that with the compact size, and you get something of an exhaust bottleneck. Which means, over time, less horsepower and torque. Exhaust headers, though, with their longer individual tubes, are designed to prevent this. But does that play out in real life? When it comes to corrosion resistance, stainless steel is a good long-term investment. For engines that will be run at high rpms and high temperatures for sustained periods of time, stainless steel construction with ceramic coating is recommended.
Most of the ones we sell are finished with your choice of chrome or durable ceramic that can be selected in the Product Options field. Ceramic coating is best suited to high heat applications. Gibson Performance Exhaust Headers are available in both stainless steel and traditional steel with chrome or ceramic coating for American 6- and 8-cylinder engines, as well as Toyota trucks.
Cast iron headers offer the advantage of lower cost, and are available for select vehicles. While cast iron is heavier than other materials, it soaks up heat better — a plus for emissions, and it prevents unwanted heat from radiating onto other nearby components.
Often found in aeronautic parts and jet engines, titanium offers the benefits of lighter weight and higher strength compared to stainless steel. Additionally, titanium can withstand very high temperatures and is naturally corrosion-resistant.
As you might imagine, headers made of titanium are a natural choice for high-performance racing applications. Regardless of the material you choose, a quality set of headers will have a substantial head flange to prevent exhaust leaks and all connections will have high-quality welds.
Finally, an engine works as a system, so the effectiveness of individual components is very dependent on the other parts. These will get you through emissions tests in all states except those following more stringent standards set by the California Air Resources Board CARB. Headers are not the least expensive engine modification you can make; nor are they the easiest accessory to install. You will, however, be knocked out by the performance improvement AND the good looks they bring to your engine compartment!
We discuss header types, their benefits, and conditions necessary for best results. The Rugged Ridge Exhaust Header with black ceramic coating. Agency Power offers stainless steel headers for Porsche and Subaru boxer engines.
If you've got a Subaru or Porsche "boxer" engine with oppositely opposed cylinders, we've got headers for you from Agency Power and DC Sports. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. Engine Performance. How do exhaust headers work to improve engine performance? Updated: Feb 11, See more car engine pictures. Do exhaust headers increase horsepower? Yes, headers are one of the easiest bolt-on accessories you can use to improve an engine's performance.
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