Keys to Choosing the Right Exhaust Headers
No matter what your project if you are aiming for improved performance, headers should be one of your first choices. However, it is important that you take the time to decide what the use of your engine will be and what type of driving you have planned. There are a number of ways this can be accomplished and at least 4 styles available.
Original Equipment exhaust manifolds restrict exhaust gases from flowing freely from the engine; their interior ports are rough and uneven, this restriction reduces the horsepower and torque of the vehicle. In most cases the consumer simply lives with it, however, car enthusiasts do not want to give away any power.
The largest market for headers will be those of you who want increased performance, primarily on the street. Others may be making an engine swap, building a hot rod or in some instances just because your buddy has them. No matter, once installed your vehicle will perform better.
What is the difference between the factory exhaust manifolds and headers?
All headers, no matter what type, are designed with free-flowing ports that improve scavenging action while taking the exhaust out of the engine more quickly than the restrictive OE pieces.
All styles, with the exception of cast, are made with mandrel-bent tubing, offering smooth transitions from the exhaust port to the exhaust system. OE exhaust systems are usually crush-bent, meaning a piece of 2” tubing can be closed in as small as 1½” at bends, mandrel-bends maintain the same tubing diameter throughout the bend. Mandrel-bent tubing moves the exhaust easily and quickly away from the head, this transition reduces HP loss because of the normal back pressure in an OE manifold.
However, for peak performance, a set of headers should be combined with a full-length performance exhaust system. Hooker and Flowmaster do exhaust right. There are 4 main types of Headers you will find, here are the features of each.
Cast iron manifolds are available for certain 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. Performance cast manifolds differ from OE by offering smooth flow and better design. Being cast iron means they will provide years of leak-free performance with less under hood noise than traditional headers.
Plus, their shorty design means you can route exhaust tubing close to your frame/floor pan for maximum ground clearance. Cast headers are heavier than a tubular version but with very little care will virtually last forever. Hooker’s Cast Performance Exhaust Manifolds are available for a limited number of GM V8 performance models. They are heavily supporting LS engine applications.
Cast would be the choice of those who want increased performance with virtually no maintenance and no annoying header leaks. However, applications are very limited.
Also known as “Block-Huggers” this design offers the easiest installation in engine bays where room is at a premium, they are also the answer for a lowered vehicle where ground clearance is a concern. Most hot rods run these since they are close to the engine and usually clear narrow frame rails. The shorty design offers performance gains slightly above the factory exhaust manifold but does not provide maximum HP in the lower ranges.
This design offers longer primary tube lengths, they usually combine into a four-way collector with a flange to bolt up to the rest of the exhaust. The extra tube lengths step up the low and mid-range performance numbers and still offer a solution for those concerned with ground clearance.
This would be the most commonly known style, once upon a time, these were all that were offered. Mandrel-bent tubing runs from the exhaust port down through the engine compartment and turns towards the rear of the vehicle. They are capped off with a four-way collector and either a flat mounting flange or a ball type connection.
This type of header offers more performance than the shorty or mid-length. Best of all it provides low and mid-range power increases, great for the street driven. If there is room this design will provide the most power increase throughout the complete power range.
Sidemount headers and mufflers deliver the most aggressive style and performance for your early Corvette, Camaro, Nova, or Firebird. Sidemount headers are built from lightweight 18-gauge tubing. Sidetubes slip directly into the collector for a leak-free seal. They are available in your choice of three finishes: Show quality chrome, high heat-resistant black paint, and metallic ceramic coating. Unless otherwise noted, these headers are designed to fit the vehicle as it came from the manufacturer.
WHAT DO WE NEED TO KNOW TO PROVIDE YOU WITH THE BEST PRODUCT?
Year make and model of the vehicle you are going to put the headers on. How will you be using your vehicle? Hard-driving, weekends at the drags, are you planning to keep it for a long time or will it be sold in a few years to start something else?
HEADER MATERIAL / FINISHES
Headers are available in mild steel tubing, coated mild steel and stainless. Mild steel versions are the most cost-efficient, usually coated with black “header paint” similar to VHT. They will require more maintenance since header paint should be redone when it becomes deteriorated.
The next step would be coated headers, usually ceramic, the coating holds heat in the header and away from the engine compartment. Plus the coating has a better look and requires virtually no maintenance.
After mild steel, there is stainless steel, two types most common 304 and 409 in our climate 304 is best, prices increase but so will longevity. Stainless will not rust and looks great, it can be polished should it start to lose its lustre. The ultimate header would be coated stainless.
HEADER TUBING SIZE
Most street headers come with between 1 ½” and 2” primary tubes. In some cases, size matters, street driven small block engines probably will respond best to 1 ⅝” whereas big blocks can handle 2”. Running headers that are too big can actually cost HP.
The more highly modified the engine the larger the tube size to gain maximum performance. Hardcore race engines will respond best to true equal length primary tubes and large collectors. The stronger the motor the bigger the tube size.
For those modifying their vehicles, headers and performance exhaust systems should be one of your first purchases, but don’t forget you have to tune your carb or EFI to achieve maximum gains. Give us a call at 416 259 9656 or if you are out of town toll-free at 877 471 6700 we will be glad to help you make the right decision.
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