They claim that they do not work, the theory is bad, etc. It is important to ask why these people are condemning the step header design. Are they selling something different? Then step headers are for you! A step-header is built by starting with a slightly smaller tube, then going up in size in one more 2-step , or two more 3-step sizes. Examining the exhaust port of most cylinder heads, it is easy to notice that they are typically NOT the same size as the header tubes. If the exhaust ports on the cylinder heads get too big, air velocity and torque suffers, and this also increases the possibility of reversion.
As the exiting exhaust gases travel through the header tubes, expansion occurs until cool enough where expansion slows, reducing air speed and scavenging effects. The longer the exhaust velocity remains at or near its highest values, the better the scavenging of the cylinders, and the more power and torque the engine can provide.
In simple terms, by starting with a slightly smaller tube, the exhaust velocity stays up. As the gases expand, it hits the next size step. This allows for contained control of the expansion while still keeping velocity speed high. This would also continue to the third step, and then to the collector. This gradual increase in size provides the maximum balance of exhaust velocity and volume. In more complex terms, we look at the pressure waves within the header primary tubes. Engine pulses in an equal-length, tuned header create what is called rarefaction , or a negative, low-pressure wave that is partially compressed and redirected back up the primary tube toward the exhaust port.
This wave reaches the exhaust valve about the time valve overlap occurs when both intake and exhaust valves are open. It is easy to believe that these rarefactions are bad, or something we don't want. However, on an internal combustion engine we actually want to control them to our benefit. The animated image below source: Wikipedia shows a sound rarefaction. The official definition states, "a reduction or diminution of an item's density, opposite of compression, especially in air or a gas.
Increasing the step too much or having to many can weaken the initial rarefaction while increasing corresponding negative pulses, which negatively affects the benefit.
This is why most step headers have just one or two steps. Three-step step headers are not as common. It shows the best single stage, two step, and three step header dimensions. Optimized for Single Primary Pipe Specs:. The same people who orginally bad-mouthed step-header technology also condemned the software used to find these dimensions. PIPEMAX is only one program of many, and most engine builders and race teams use a variety of software simulations as a guide or baseline when testing and developing engine components and combinations.
These programs are extremely detailed and intricate tools designed to help the industry professional. Oddly, many of the original detractors have since embraced step header technology. Although this may have offered some benefit in a little weight savings, it was hell on flange gasket life and proper sealing stable and consistent clamping force during thermal cycles.
With the expansive properties that exhaust heat provides, header flanges are heated stretched and cooled after engine shut down repeatedly to the point that loosens bolts and makes gasket failure eminent. The thicker flange provides better clamping force and less movement, and header bolts are not exposed to as much movement.
Therefore, proper sealing can last almost indefinitely. If after reading this information you still have questions, please create a support ticket on our Helpdesk. All rights reserved. Do you want to improve the bottom end, do you need to turn more rpm at the top? The rpm band of the engine will play an important role in determining the primary size and length of the exhaust primaries.
Also, consider the cylinder head. Different cylinder heads have different mounting bolt designs and port sizes. Steven Zimmerman, of Stainless Header Mfg. And design considerations should consider primary tube size, material type, and collector merge diameter. Sizing the primary tubes correctly is a great place to start. Getting this right will create the maximum power and the most useable powerband. This is where vehicle weight, transmission type, and gearing come into play. For instance, a Chevy in a lightweight stick shift stocker will likely be launched at a high rpm, and the engine will never see the low side of the powerband.
In this case, you may opt for a larger header that provides maximum horsepower at peak rpm without worrying about any loss of torque down low. In contrast, the same engine in a heavier automatic stocker, say a station wagon, may require a smaller primary and even an X-pipe added to the headers to increase torque at low rpm. Of course, other aspects will drastically alter the sizing, particularly power adders, such as turbochargers, blowers, or nitrous.
On top of this, there are many great software programs that can run a myriad of equations and algorithms to help determine header sizing, on top of many other features. Those programs are great for us to have, as we deal with header design every day, but for any fabricator building a one-off set, the expense of a software program may not be worth it. We have the experience and information to help any builder. We also asked: How should a racer determine if step headers are needed?
Stepped headers give the benefit of a higher velocity exhaust gas at the cylinder through a smaller tube ID, while allowing the benefits of higher flow capabilities further downstream on the larger tube ID. Another beneficial effect of the stepped design is the anti-reversion property of the tubes. Having the step in the tubes will create small overlap and pressure differential, ensuring the exhaust continues to move downstream, and prevent reversion back toward the exhaust ports.
There is always going to be extra cost associated, and any engine that operates within a narrow bandwidth of power may not see some of the benefits that a wider powerband engine may see. On top of this, the larger tubes, by nature, take up more space in an engine bay, which can be a packaging nightmare in compact applications. It can also be detrimental to boosted applications, particularly turbo setups, as it robs some of the exhaust velocity, causing an increase in turbo lag.
To really see a benefit from each individual step, certain lengths will be required. Burns will help racers select primary size and length headers after determining bore, stroke, compression ratio, inlet and exhaust valve sizes, camshaft design, and engine-operating rpm range. The engine rpm band is the most significant factor in determining primary length, while displacement and power are important to determine primary tube diameter.
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Hey I have a ford maverick My engine v8 from a ford pick up The room is very limited looks like would have to cut Maybe not I want the best headers to increase power. This is a new motor listed in the GM performance catalog.
I bought this motor with EFI and complete serpentine belt system to include AC pump, alternator, and power steering pump. This set up leaves some issues to be resolved, such as custom made AC and power steering lines to mate up with existing stock parts. I believe I have solved the new fuel system issues to include new fuel tank, electric in tank fuel pump, fittings and flex line to motor fuel rail. With help from a childhood friend that is a fantastic mechanic we will bring this 49 yr old machine into the 21st century.
That still leaves me with a couple old school problems to solve. I need help with which headers to buy that will fit the car. This project will take all winter and one thing my mechanic Dad taught me is take your time and do it right. Any assistance on header choice would be greatly appreciated.
Hey Jim. Hey I was wondering what would be a good set of headers for my 94 GM 5. Pingback: Best Long Tube Headers for 5. Shortys make more low and mid range power and torque. Long tube headers make more top end power than shortys but sacrifice low and mid range. Time for header purchase for my Mustang with Edelbrock top end E street package. Any help would be appreciated. How about Chevy short wheel base truck.
Subtract a V6 add a gen 1 stroker V8. Question: LS flange the same as gen 1?
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