Most racing engines will work best with (primary) tubes between 28 and 30 inches long. It is also very important that all header tubes are as close as possible to the same length. The tubes from the rear cylinders are closer to the collectors and need a few extra twists and bends to be as long as those (tubes) at the front of the engine.”
What is the difference between a header and a tube?
What determines the correct primary tube size?
How much torque does a 425 horsepower engine have?
How to control exhaust velocity?
What is the collector size?
Why do headers need a mini starter?
How to build a step header?
See 2 more
Are equal length headers important?
This results in lower cylinder temperature on an equal length header, which can help prevent ringland failure. Another benefit of equal length headers is the balance of backpressure at the exhaust ports, which will improve volumetric efficency and overall top end performance.
Should I get short or long tube headers?
Shorty headers aren't as loud as long tube headers, although they'll definitely have better sound than your stock manifold. You can choose unequal length headers for better sound, but equal length is the way to go for consistent gains in performance.
Are short tube headers legal?
The shorty retains the OEM cat(s), therefore, it can be made legal in all 50 states. We realize headers will help make more power and torque on nearly any engine when upgrading the stock, cast manifold.
How do I know what size header tube to use?
However, for a street car, Don recommends the following guidelines: 200-325 horsepower look for 1 1/2-inch primaries, 275-425 horsepower use 1 3/4-inches, 400-500 horsepower opt for 1 3/4 to 2 inches, and 500+ horsepower look for 2 inches or greater. Keep in mind, smaller pipes mean more low-to-mid-range torque.
How much HP will shorty headers add?
How much hp do shorty headers add? On a stock engine, around 3 hp above the usual.
Do you need a tune with shorty headers?
Shorty headers are not enough of an aspiration change to require a tune, unless you are removing the catalytic converters at the same time.
Do shorty headers do anything?
You'll find long-tube and shorty headers are both common mods for late-model Mustangs, especially in the Fox arena. The benefit of shorties is relative ease of installation. In most cases, they will connect to your existing mid-pipe and you'll see a gain in power.
Why are open headers illegal?
What are "open headers?" It's simply when there is no pipe attached after the header, hence no exhaust system; hence illegal.
Do shorty headers make truck louder?
Car headers do not make your car louder as compared to the stock exhaust manifold. This aftermarket addition is used to improve the performance of your car and give you a cleaner-sounding exhaust. The actual volume of the exhaust won't change.
Can headers be too long?
The "Request header too large" message is thrown with an HTTP error code 400. This error occurs if the size of the request header has grown so large that it exceeds the maximum-allowed size.
What size header do I need for a 20 span?
For a 20-foot spans, the wood beam has to be at least 16 inches in depth and 8″ in width (4-2×16) used for residential building or projects.
How long should my header be?
It went like this: Measure the span in feet and add 2 to that number. The sum will be the height of your double header in inches. For example, if the span is 4 feet, add 2 to 4 for a sum of 6. Therefore, the header would need to be made from doubled 2x6s.
How much HP will long tube headers add?
Generally speaking a set of long tube headers on an American V8 can yield 20 to 30 HP without other modifications on vehicles with a stock exhaust system. Also headers generally require ECU retuning.
Are Longer headers better?
Long Tube Headers This design allows for major performance boosts, an aggressive sound, and is built to handle future power modifications. The long tube design creates negative pressure in the pipe, pulling more exhaust gas out of the cylinder, and reduces backflow pressure.
Do shorty headers make truck louder?
Car headers do not make your car louder as compared to the stock exhaust manifold. This aftermarket addition is used to improve the performance of your car and give you a cleaner-sounding exhaust. The actual volume of the exhaust won't change.
Primary Header Tube Length and Diameter Calculator - Wallace Racing
The following calculator can be used to calculate the header dimensions best suited to your combination. The input terms are below: Bore/Stroke is given in inches .; Exhaust Valve Opening Point is given in degrees before bottom dead center (BBDC). Entered values should be greater than 0.
What size headers should I buy?
For performance engines, operating at higher rpm, you can use the formula below. Note. This formula will find the Required Area of the primary tube in square inches. This is NOT the diameter. Further calculations are required to convert area to diameter.
The Correct-Sized Headers Will Give You the Best Performance - MotorTrend
Tri-Y long-tube headers, which were conceived on Shelby Mustangs and Cobras in the 1960s, combine a short primary that is paired with another cylinder that is synchronized in the firing order into ...
Welcome to Nightrider.com - Modern Engineering - Old School Service
Welcome to Nightrider.com - Modern Engineering - Old School Service
What does header tube size do?
With all other factors being equal, the proper header tube size will allow you to obtain a superior scavenging effect with an increase in exhaust speed. Some folks will even tell you that the exhaust valve diameter determines the header tube diameter (not exactly correct).
How does header builder control exhaust speed?
To a point, a header builder can control the speed of the exhaust gas by changing the diameter of the primary tube. The smaller the diameter of the tube, the faster the exhaust will flow. This is an example of a “zoomie” we discussed ...
How does a header control the speed of the exhaust gas?
To a point, a header manufacturer can control the speed of the exhaust gas by changing the diameter of the primary tube. The smaller the diameter of the tube, the faster the exhaust will flow (keeping in mind the exhaust flow slows as it cools).
What is header set?
If properly designed, the header set will provide a beneficial pressure balance between the intake and the exhaust. An engine benefits from two different types of scavenging: Inertial scavenging and wave scavenging. Header design can have an effect upon both.
Why is header builder important?
Here, the engine will gain an advantage, because there is less residual exhaust gas remaining in the combustion chamber (which can foul the incoming charge of fresh fuel and air). By manipulating the diameter and length of a specific tube, a header builder can influence the size of that low-pressure front.
What are the common header questions?
Common header questions are center ed around tube diameter, tube length, collector diameter, collector length, and so on. Some folks will tell you none of this matters. Others will tell you it all matters. We tend to agree with the latter, but when it comes to the racing world, one thing is pretty clear:
What is the purpose of a header?
If properly designed, the header set will provide a beneficial pressure balance between the intake and the exhaust.
What size header for GBody?
Hedman makes 1.5" long tube header for the GBody. May work in a Chevelle with a little massauge.
What NASCAR headers did Smokey Yunick make?
Smokey Yunick had stainless steel four tube headers made for Fireball Roberts Pontiac NASCAR effort. They even had a pontiac part number. NASCAR impounded them and I believe they are still in the museum at Talledaga.
What happens when exhaust is tuned correctly?
When the system is tuned correctly not only does the exhaust leave the cylinders in an unhindered fashion, but also pressure waves below atmospheric pressure act on the cylinder during the valve overlap period to effectively scavenge the combustion chamber of the last remnants of the exhaust.
Why is the primary pipe length important?
Primary pipe length is usually considered to be the most important dimension to get right. While this may be so in most instances, it is not the case for a two-plane—cranked V-8 typical of Detroit products we commonly drive. The suspected reason for this is the unevenly spaced firing pulses seen at the collector, but whatever the reason, it does (for once) all work in our favor, as we'll see later.
Does a parallel collector work?
Fortunately, there is not much to cover here. First, the original parallel collector works well, but my dyno tests indicate that the merge collector has a slight edge in terms of power bandwidth, torque, and horsepower. In another area, if the design is sufficiently well developed, the merge collector has the ability to pull more vacuum via the evac-u-pan system, if one is being used. Notwithstanding, the merge collector is a little more costly to make, so ultimately you will have to go with whatever suits your budget.
Which is better, shorty or long tube header?
They are more like a work pickup or a daily commuter that shows a lot of hauling and towing. So, in a word, shorty headers are the better ones between shorty and long tube headers.
Why do headers come out of the collector tube?
But they will come out into the collector tube several times because of the spacing of the collector tubes. Headers are the directors mostly as they make sure each cylinder can use the collector tube in turn so that it can help to prevent back pressure as well. In this way, headers improve and enhance the performance of an engine.
What is header in a car?
Headers are the first stop for exiting exhaust manifold gases from the engine of the vehicle. Although some people interchange the term manifolds and headers because of this, they function differently.
What is a stock exhaust header made of?
When your stock exhaust manifold is made out of cast iron or stainless steel, then headers can produce a variation in the materials. But when the stock manifolds are prone to get practical, then the pipes of a general header will seem bold and wild.
What is a header in an engine?
Headers are comprised of several tubes that connect to each of the cylinders of your engine so that they can help to extract the exhaust out.
Why are headers important?
Design and makeup of the headers are two of the key factors in the performance of any vehicle because otherwise, the RPM will vary which will lead to varying performance.
What does a longer header mean?
Longer tuber headers result in lower exhaust manifold back pressure and it means a boost or enhancement in horsepower as well as better oxygen intake.
Why is header tube size important?
The most important part of a header's design is to get the tube diameter selected correctly - whether the engine is used in a daily driver situation or used for all out racing - because that diameter establishes the gas velocity inside of the header which then establishes the primary scavenging characteristic of the header. If the header tube diameter is selected correctly, the engine then produces a noticeable increase of power over a wide rpm band which makes correct size selection almost more beneficial (almost more important) for a street car than it is for a a race car. If the header tube diameter is too big, the top end power might go up a a little but the bottom end and mid-range power will actually be reduced by a far larger amount. (We've seen engines experience a 5-10% loss in power in the mid-range to get less than a 1% gain on top end just by oversizing a header by ONE tube size!) To a racer, where, hopefully, the mid-range isn't important, the 1% gain might be very important but, to the guy driving on the street, the 5% (or more) loss in mid-range power is far more noticeable than the 1% gain at high rpms (note that this assumes that the exhaust system - after the headers - is NOT the major restrictor at high rpms). Keep in mind that the guy on the street is also NOT driving at full throttle at high rpms all the time so he may actually not even notice the minimal loss of power at high rpms with a smaller tube diameter because the engine is hardly ever used that way - BUT he will definitely notice the loss in mid-range and bottom end power with a larger tube. (Note that having all of the header tubes the same length as well as long enough to function optimally in the engine's rpm range is a critical part of this design "equation" because the header has to scavenge ALL of the cylinders to the same degree if the power gain for each cylinder is to be achieved equally as well as optimally - which cannot be achieved in an UNequal length design. Another point to be made is that deliberately downsizing a header to further increase bottom end and mid-range power with an acknowledged acceptance of some top end power loss is a good "trade" for many as the loss of top end power isn't as important as is maximizing performance in the lower part of the rpm range.)
What happens if you add 6" tube length?
Assuming that the tube length is near correct already, adding 6" of tube length will strengthen mid-range and bottom end power but will diminish top end somewhat. If the tube is actually too short, you might get a power gain over the entire rpm range of the engine! (But don't expect that to happen here.)
What is the worst header for a street rod?
P.S. The absolutely worst header to use is a block hugger style design as it is way too short, has unequal header tubes, and usually has a collector with a very short transition length that is also not shaped correctly (i.e., a collector design that is very restrictive to flow). I've talked to street rodders in this area that have switched from exhaust manifolds to a block hugger style header and not only found that performance got worse but the engine ran 20-25 degrees hotter afterwards. If this happens on carbureted engines, what's going to happen to yours that is blown? It has to be even worse! It wouldn't surprise me at all to see you lose 15% or more power in the mid-range - particularly at part throttle - if you do what is usually done. Gas mileage will also be much better if the exhaust side is optimized for efficiency. Relative to header design, this means designs very much different that what seems to be typically used in street rods as street rodders usually pick form first, function second (often decidedly second). I hope that you are different from the majority.
Why is the collector diameter important?
The collector diameter isn't a major concern on a street vehicle because the secondary gas velocity after the header tubes is established more by the entire exhaust system then by the collector diameter. However, when the headers are open to atmosphere, the diameter of the collector becomes VERY important because that diameter then establishes the gas velocity immediately after the header tubes. Here, again, usage determines header design.
What are the problems with headers?
One of the biggest problems guys have with headers is that there is very little experienced, objective discussion about header design. Most of the writers for magazines are not well informed and seem to reflect more what advertisers are trying to sell. They certainly won't "blast" somebody for building a lousy header (or any other product, for that matter).
How much does a 1/8" tube diameter change?
On a number of occasions I've sold parts to somebody where they built a turbo header, ended up disappointed with the results, ordered more parts to build a smaller header, and were amazed at how much better the engine ran just reducing the tube size by 1/8"! However, that 1/8" reduction in tube diameter often represented an area change of 15-20% which is quite a substantial change. (Most guys don't think of cross-sectional area changes that vary with the SQUARE of the radius change - they just think of the change in diameter - so most don't really understand how BIG an 1/8" change in diameter can actually be unless expressed in percentages.)
Can you build a header for a turbo?
I've never built a header for a Turbo so don't feel it is appropriate to talk about designing them. However, I've sold lots of parts to fellows building them and have learned considerably from their efforts (and mistakes). One thing I have learned is that sizing is very critical as it determines the velocity of the gases inside the header and, from that, greatly affects the turbo's operation.
What are the different types of headers?
Aside from 180-degree headers (which are unquestionably a nightmare to build for any car and well beyond our scope here), there are two different types of headers: 4-into-1 and “Try-Y” (4-2-1-collector).
What is a 4-in-1 header?
There is a variable to the conventional 4-into-1 header, and that’s the merge collector. With a series of both exhaust waves and sonic waves entering the collector, it’s easy to see that there is probably a bunch more to collector shape than first meets the eye. For example, Hooker tells us that a merge collector minimizes the reflected wave, so it has less effect upon the inertia pulses. The actual hourglass shape of this collector design serves to regulate the high and low pressures. It also tends to speed up the velocity of the gas flow. Additionally, the shape of the collector (particularly in the case of a merge collector) helps equalize the transition of the individual exhaust tube gases.
Why is the neck of the hourglass important?
The neck of the hourglass is important too. By reducing the size of the neck, the exhaust gas velocity will increase as it is carried into and out of the secondary tube (collector). This form of collector can prove efficient; some folks have experienced an actual increase in the EGT (Exhaust Gas Temperature) in certain applications. The reason is the header assembly is extracting more of the air/fuel mixture out of the cylinder and likely burning it in the collector. Because of this phenomenon, there’s chance the camshaft timing events may have to be revised. Obviously, the same applies to the carburetor jetting.
How does try y header work?
Try-Y (4-2-1) headers collect the exhaust by pairs of cylinders that are as far apart as possible in the firing order. The idea is the gases racing past the silent tube will scavenge a vacuum in it, reducing exhaust reversion. We have found no advantage in this design for the majority of racing applications.”
Why is the shape of the exhaust collector important?
The overall length of the merge collector is important, as is the angularity of the tubes that physically “collect” in the collector.
How to tell if header changes are good or bad?
The ET and MPH of the car will tell you if the header changes you made are good or bad. When it comes to headers, the header builder is always faced with compromises. In some cars, there simply isn’t room to make headers that are the right size, the right length, and with primaries of equal length.
Why do you need headers?
The headers need to compliment the engine you build. If you build an engine and you need to revise it to suit the car, changes in the camshaft (for example, advancing the camshaft) will have a far greater effect than making changes to the collector.
How many RPM does a small tube header need?
As you can see from the charts on this page, small tube headers do not lose their edge in horsepower and torque until you exceed 5,500 RPM. Even if you're running a radical camshaft and blower, you're better off sizing your headers smaller rather than larger, unless you plan to spend most of your driving at full throttle.
What size primary tube for a small block?
If you are using the engine in the 1,500 to 3,500 RPM range, which is typical for a street-driven vehicle, you definitely want 1-1/2" to 1-5/8" primary tubes for any small block ...
Why are primary tubes so big?
The fact is, primary tubes that are too large actually cost you torque and horsepower by slowing down the rate at which the exhaust gases travel through the system. Think of your engine as an air pump. Every time the exhaust leaves the combustion chamber it is being forced into the primary tube for that cylinder.
What is a stock manifold?
Stock manifolds are mass produced and designed to clear all the accessories offered for any vehicle the engine block may go into . So naturally, factory exhaust system performance is compromised by manufacturing requirements. Tubular headers are built for improved flow, torque, and power---and their design can be very specific.
Do equal length tubes produce more power?
Equal length tubes can produce more power, true. However, they must be the right length for the specific motor at the RPM range where you want the power. What that means is lots of custom fabrication and dyno testing, which translates into lots of time and money.
Can Sanderson headers be custom made?
We build hundreds of custom fabricated headers for one-of-a-kind cars, but for most vehicles you can get the performance you need with a set of Sanderson's right from our extensive product line.
Is a header a good investment?
It is no secret that a good set of headers is one of the best performance investments. In fact, most engine builders say that headers are one of the first things you should upgrade to when modifying your engine. But before you plunk down your hard-earned cash, remember a couple factors determine what will work best for your particular application.
What is the difference between a header and a tube?
Smaller primary tube diameters keep the air velocity up for more torque, where a larger tube size is better for upper RPM (above 6,500 RPM) performance. If the headers are too small for the application they will cause restriction and increase heat in the engine. Too large a header will reduce torque output of the engine and increase the possibility of exhaust gas reversion---again increasing heat. Simply put, torque is related to air velocity (the faster the air/fuel get through the engine), and horsepower to the volume of air/fuel that processes through the engine. The faster the air enters and exists an engine the more torque the engine makes, and the more volume of air that passes through the engine, the more horsepower the engine will produce. A balance of both is necessary for typical street applications, where racing-specific engines are often designed within specific RPM range requirements.
What determines the correct primary tube size?
When considering the correct primary tube size, decisons must be based upon a multitude of factors. For example, engine size, horsepower output, average operating RPM, use of the vehicle, and if any other power-adders (nitrous or supercharger) are being used. What type of cylinder heads are being used? What is the bore and stroke of the application? What are the camshaft specifications (lobe centerline, exhaust opening, lobe lift), the rocker arm ratio, exhaust valve size, and more? What does the rest of the exhaust consist of (piping size, muffler type and how many)? What is the vehicle weight, gear ratios, and transmission type? The more data available, the more accurate the header size recommendation will be.
How much torque does a 425 horsepower engine have?
Having 425 peak horsepower and 449 ft/lbs of torque under the hood is decent, but really, anything over 5,000 RPM in this example merely amplifies wear and tear on the engine. Torque is falling, and peak horsepower occurs just 400 RPM higher (900 RPM over peak torque). The big torque numbers occur between 3,000 and 4,500 RPM. Therefore, even if driving this engine hard (or racing it), we'd want the shift points to allow the engine to fall to roughly 3900-4,200 RPM for maximum continued acceleration (pull).
How to control exhaust velocity?
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."
What is the collector size?
Collector size is measured in both length and diameter . In a shorty, street rod type application the collector length is of no concern. In these headers the collector is merely a union point for the primary tubes, and a connection point for the vehicle's under chassis exhaust system. The collector diameter is important in that the application requires a diameter compatible with both the power output of the engine, and the under chassis exhaust piping size that completes the rest of the vehicle's exhaust system. Of course, most headers come with a collector reducer to meet the size of a smaller exhaust system, but with a shorty or mid-length header the collector is already manufactured using a standard sized complimentary collector for that header and the engine it fits. On these applications it is common (and cleaner) to have a one-piece down pipe fabricated instead of using the reducer. If someone does not have access to a muffler shop, tubing bender, or other fabrication equipment, the reducer provides a weld point for under chassis exhaust piping connection.With a full length header the collector diameter is usually fairly large in all but those designed for light duty passenger cars, trucks, SUVs and motorhomes. This is due to the fact that most full length header designs are for max power, and upper RPM use. Additionally, in racing applications we often use the collector length to slightly tune the torque output of the engine.
Why do headers need a mini starter?
Many headers require the use of a mini-starter to ensure adequate header to starter clearance. However, upgrading to a mini-starter is actually beneficial for many more reasons.
How to build a step header?
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. Header flanges are rarely the same size as the tube diameter, and often not a direct match in dimension to the exhaust port itself unless it is a race-only application that the user/builder modified---or again, someone looking to spend the time and expense to find every last available 1/4-horsepower. 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.