How to select the right header...

[geoklass]

This is a FOX chassis "car", or at least what's left of it. We cut up a "perfect car", cut out everything that was in the way, and removed everything from behind the firewall, to make it easy to roll around the shop while designing headers for that style vehicle (1979-1995 Mustang). All headers are designed with the OEM height engine mounts and OEM K-Member in place. If it fits in this car, it will fit in your car, UNLESS, you have made too many changes to the chassis from the firewall forward. We used the same process when designing the headers for the '65 through '73 Mustangs, too.

RCI CUSTOM HEADERS - (909) 552-3690 - [email protected]

 

[geoklass]

The original header (Header #1) for that specific application is fabricated inside the cut-away car. Header #1 is NEVER sold, it is used to make the steel fixture shown above. It's kept as a reference so that as new headers are built in that fixture, we can compare where all the tubing cuts are, to insure that the customer gets a header that will FIT, assuming of course that his FOX chassis vehicle is as "OEM" as the one in this photo. Aftermarket K-Members and aftermarket Motor mounts may LOOK like they are the same as OEM, but some are and some aren't. You can see in this photo how this header (2" primary) has some tubes on the inside and some on the outside of the steering shaft, in order to both fit and also to insure a nice radius. This is what we mean when we tell people that if your engine mounts lower the engine, you may have interference with either the chassis or the steering shaft.

RCI CUSTOM HEADERS - (909) 552-3690 - [email protected]

 

[geoklass]

As I said on our website "If it was easy, anyone could do it". www.georgeklass.net

RCI CUSTOM HEADERS - (909) 552-3690 - [email protected]

 

[General karthief]

The December issue of Car Craft has a short vrs long tube header dyno comparison, the long tube was 1 3/4" and the shortys were 1 5 /8" , they also tested a set of factory shorty headers and stated there was no difference between the factory and the aftermarket shorty headers, the test mule was a 351w crate motor with 385hp claim.
I bring this up because of what you say about the collector design, obviously the short tube headers have a 'ball socket' type merge point (they added about two foot of pipe to the header) and the long tubes have a collector and three bolt flange with about a 18" extension . I would think the results a slightly bias toward the long tubes.
#1 header tube size (I state this because of the advertised hp of the test mule)
#2 merge point differences (ball socket vrs traditional collector)
#3 the length and size of the extension after the header
I realize the difference in hp and tq are, in reality, small but it starts a conversation.

 

[geoklass]

The December issue of Car Craft has a short vrs long tube header dyno comparison, the long tube was 1 3/4" and the shortys were 1 5 /8" , they also tested a set of factory shorty headers and stated there was no difference between the factory and the aftermarket shorty headers, the test mule was a 351w crate motor with 385hp claim.
I bring this up because of what you say about the collector design, obviously the short tube headers have a 'ball socket' type merge point (they added about two foot of pipe to the header) and the long tubes have a collector and three bolt flange with about a 18" extension . I would think the results a slightly bias toward the long tubes.
#1 header tube size (I state this because of the advertised hp of the test mule)
#2 merge point differences (ball socket vrs traditional collector)
#3 the length and size of the extension after the header
I realize the difference in hp and tq are, in reality, small but it starts a conversation.

Not knowing anything about the engine, or the cylinder heads, or the RPM range, etc, etc, it's kind of tough for me to make any relevant assessment here, but I tell people all the time, don't laugh about 1 5/8" headers, long tube or not. If 1 5/8" headers are the right size for a particular engine, bigger headers are not going to improve it. I tell people all the time, think about the restriction in the exhaust system, and where it is. In my opinion, it's in the exhaust valve area. 95% of all the exhaust valves in aftermarket Ford cylinder heads are only 1.60" in diameter. A 1 5/8" header measures 1.62", so we could say that they are the same, however, the exhaust does not go through a 1.60" hole in the exhaust port because the inside of the valve seat is probably only about 1 1/2" in diameter. THAT is where the restriction is, particularly on a street type car. Engine builders, I have found, typically seem to spec out header diameters that are too big for their street/strip customers. Unless your engine is pumping out 450 to 500 horsepower, my opinion is that you are better off with a 1 3/4" header than anything larger, for a street/strip engine. You can't make up in headers what your cylinder head exhaust port won't let you do. It's like an hourglass. Everyone can visualize an hourglass, a tube on the top, a tube on the bottom, and a restriction in the middle. Doubling the diameter of the tube on the bottom will NOT get the sand past the restriction any faster. The restriction is the restriction and its not going to go away by making the tube underneath it bigger.

 

[96pushrod]

Did someone say flanges? Our flanges are designed so as not to interfere with either the spark plugs or the spark plug socket needed to install or remove the spark plug (something that many header companies seem to forget about).

RCI CUSTOM HEADERS - (909) 552-3690 - [email protected]

Man I had this problem with a set of headers. I had it clearance the flanges where I needed to get a spark plug socket in. Was a pain in the ass.

 

[geoklass]

Man I had this problem with a set of headers. I had it clearance the flanges where I needed to get a spark plug socket in. Was a pain in the ass.

I don't think that many people (or many header companies) realize that different brand cylinder heads have different spark plug angles, and the flanges have to be designed accordingly. This is the difference between a "one size fits all" header and one built for your specific combination. Here's another potential problem area, "head studs". Head bolts don't stick up very much and don't cause issues with the flanges, but some heads using head studs do protrude higher than the head bolts would, and won't let the flanges drop down far enough to line up with the ports or the flange bolt holes in the heads. Provided that the customer mentions that he has head studs when ordering headers, we can modify the flanges to clear the head studs. I have also seen some header company flanges that stick up too high, and can keep the valve covers from clamping down on the valve cover gaskets, causing oil leaks.

RCI HEADERS - (909) 552-3690 - [email protected]

 

[geoklass]

This is a 409 Chevy engine mounted in a 1960 series Chevy II, designed as an all out race car in the A/FX class.

This is what the header looks like without the front end of the car wrapped around it. At the time, NHRA permitted open headers in the class but still required that the stock exhaust system was intact (exhaust pipes, mufflers, etc.). This is NOT a long tube header, this is what we call a "Mid Length" header today.

RCI is one of the few (maybe the only) header company that offers a competition style "Mid Length Header" for 1964-1973 and 1979-1995 Mustangs, with primaries of 1 3/4", 1 7/8" or 2". Do your headers interfere with transmission removal or changing clutches? These "Mid Length Headers" will eliminate that problem...

RCI Custom Headers
(909) 552-3690
[email protected]

 

[General karthief]

Do they work well with full exhaust

 

[geoklass]

Do they work well with full exhaust

Yes they do. In fact, on the dyno with a full exhaust, the difference between a Long Tube header and a Mid Length header is almost un-measureable.

 

[geoklass]

It wasn't just Super Stocker and F/X cars that used "Mid Length" headers. Some of you older guys will remember that the term "Long Tube" header was not used as a description for headers. Headers were just called "Headers" and the length of the primary tubes was not much of a consideration. A well designed header had nice radiuses and got the exhaust out and the collector had some scavenging characteristics. Some racers preferred the 4 into 2 into 1 design (Tri-Y design) and some liked other designs and for the most part there was no consensus. Headers, like many other high performance components were always a compromise, both in primary diameter, primary length, and even collector size. The "perfect" sizes does not exist, since an engine does not run at only one RPM, it runs through a bunch of RPM's, from bottom end, mid range, and top end. And when you install a full exhaust system on the car, the header design is even more of a compromise. There is nothing wrong with a long tube header, if anything, it seems to favor the bottom end more than the top end, but every performance component on your car favors one end of the spectrum more than the other end. A bigger carburetor favors the top end more than the bottom end, as does a radical camshaft, but we have to remember, a car is NOT a dyno, it has to make good power all along the RPM curve, not just at one end or the other, and that is the compromise.

The Tucker & Stoll AA/SR above (Supercharged Oldsmobile engine) is an interesting example, since it was basically unbeatable in NHRA competition in the Street Roadster Class. These headers are an early example of a Mid Length header. This was no light weight car, it weighed more than most FOX chassis Mustangs, around 3400 Lbs. It had an all steel body (a 1928 Chevy roadster body) and a stock frame, and because of the crappy drag slicks back then, a lot of ballast in the back. The Olds engine was no lightweight, lots of cast iron in the block and heads. One of the bigger advantages in this car was that it was one of the first to use the B&M "stick-hydro" transmission, an indestructible 4-speed automatic trans. The engine made good all around power, we took it out of Dave Stoll's ski-boat (that ended our water ski season at Lake Tahoe that year).

How does a boat motor work in a car? Just fine, the engine does not know the difference, it makes good power or it doesn't. In a ski boat, there is no such thing as the need for bottom end, if you jump on it from a standing start, it just spins (cavitates) the prop (kind of like blowing off the tires in your car). If you jump on it when it's just cruising along at 40 MPH, you had better be hanging on for dear life. Tug boats have big props, ski boats do not. By the way, there is no such thing as "long tube headers" in a ski boat, there is no room for them.

When I talk to guys on the phone about headers, of course we will give them the headers that they ask for, but I always question them about what they do with their car, whether it's an all out race car or a total street car or a street/strip car. Everybody's needs (or wants) are different and sometimes I wind up talking them out of what they say they want and selling them something that will work just as well (or better) for less money. A lot of guys want Long Tube headers, not because they are the right combination for their car, but because "everybody has them, so they must be the best choice". Many times the Long Tubes are the best choice, and many times the Mid Length headers are a better choice, if for no other reason than they cost less than the Long Tubes, and the horsepower difference is so minimal. This is why I love my job...

George Klass
RCI Headers
(909) 552-3690
[email protected]
www.georgeklass.net

(I'm frequently not near the phone, please send me an email note with your phone number and I will call you back.)

 

[geoklass]

Advantages and disadvantages of Long Tube Headers:

I guess it can be said that Long Tube headers are the defacto standard when it comes to high performance exhaust systems. The primary advantage is that the length of the primary tubes is more in line with the general power of the torque (or power) curve of the engine. Think of a one cylinder engine, which for the sake of simplicity has only one intake and one exhaust port. On the exhaust side, it has one exhaust primary tube. In theory, the length of that tube should correspond with the RPM where the maximum power will be. If the engine is set up to produce the power at or close to the bottom end of the RPM range (let's say 1500 RPM), the length of the tube should be a certain length. If the engine is set up to have the maximum power in the mid range of the RPM curve (let's say 3000 RPM), the length of the tube will be a little shorter. And if the power level is designed to be achieved at the top end of the RPM curve (let's say 6500 RPM), the length of the tube should be even shorter.

Of course, we are talking about theory here, not reality. Very few engines run at only one RPM.

Now, let's take our one cylinder engine and add seven more cylinders (a V-8). Let's say that based on the power level of our engine (and other factors), we determine that the primary tubes should be 30-inches in length. Based on that, we should have headers with eight "equal length" 30-inch long primary tubes. But here is where things get tricky because if we are building headers for a normal automobile, the headers have to fit into a fairly cramped area, and clear the steering, the chassis, the starter, and a bunch of other stuff, and still fit into a common collector. Plus, the cylinder head is about two feet in length, front to rear, which means that the front exhaust port is about two feet further forward than the rear exhaust port on that head. How in heck can you get all the primary tubes to be equal length in that scenario? Well, it's almost impossible. You can lengthen the rear primaries by putting some bends in them, in effect having them aim forward before them curve to the rear to give them more length but it's still almost impossible to have them come out to be dead nuts equal. The good news is that it is not that big a deal. It just means that each of the eight cylinders has a "slightly" different length which might mean that each cylinder has a slightly different RPM power curve. Again, no big deal because we are not running at only one RPM power curve (which is why they call it a curve), we are running at a power "band", which means that we want power from maybe 2000 RPM up to 7000 RPM. Like everything else in life, the length of the primary tubes in a exhaust header are a "compromise", just like the length of the intake runners are in the intake manifold.

RCI Long Tube headers have a typical primary tube length between 28-inches and 33-inches.

I mentioned "other factors" when determining where the RPM power band should be. One factor is the weight of the car, another is how the car is to be used (street only, street & strip, strip only), another is number of speeds in the transmission, and also the rear end ratio. 30-inch primaries are about right for a 3000 car with a 3 to 5-speed transmission, a 3:73 rear end and about 400 HP, that can run well on the street (which means it has a full exhaust system) and at the track.

What are the disadvantages of Long Tube headers?

They usually cost more, they are usually more difficult to install, they weigh more, and they can get in the way of some transmissions (not an issue with RCI Long Tubes, ours are custom designed to fit around any and all transmissions or bell housings), and there is a possibility that your ground clearance may be reduced.

I will follow up with similar discussions about RCI Mid Length headers and RCI Front Exit headers over the next few days

George Klass - RCI Headers
(909) 552-3690
[email protected]
www.georgeklass.net

 

[TOOLOW91]

There are many types of headers available for your FOX chassis car. There are shorty headers, long tube headers, mid length headers, front exit headers, and maybe some I can't think of. Our company (RCI Headers) manufactures Long Tube Headers, Mid Length Headers, and Front Exit Headers, in primary sizes from 1 3/4" up to 2 1/4". The first consideration is, "what am I going to do with the car?" Is it a street car, or a drag car, or a street/strip car? The majority of people that call me on the phone tell me they have a street/strip car, or at least, they think they do. I ask them, "How many miles do you drive your car a year?" The average is 6,000 to 7,000 miles. Then I ask them, "How many times a year do you race your car at the drag races?". Answer, "Oh, maybe four or five times a year." My next question is, "And on the average, how many passes do you make when you go drag racing?" Answer, "Maybe about six passes." So, with that information we now understand that this enthusiast runs his car at the track maybe five times a year and averages six passes each time. Those six passes (at a quarter mile per pass) equal 1 1/2 miles, multiplied by five times a year, for a grand total of 7 1/2 miles of racing, and maybe 6,000+ miles of street use.

Folks, that is not a street/strip car. That is a street car that is used for racing a few times a year. Does he need an all out race header or a high performance street header? Some of you guys probably think that an all out race header will work great on the street. But think about it, an all out race header is designed to make horespower above 6,000 RPM, or 7,000 RPM. A well set up drag car leaves the starting line at the drag strip at about 5,000 RPM. They have no interest in mid range torque (3,000 to 5,000 RPM) because the drag car does not operate in that RPM band. But that's where a good running high performance street machine operates. Most street racers rarely exceed 6,500 RPM very often, so why buy a header that is designed to function best in that range, at the expense of making power in the RPM band that the street car typically operates in?

Like almost everything else in life, header design is always a compromise. As the Marketing Manager at RCI Headers, I would like to discuss this stuff and get some feedback from you. I have been the Marketing Manager at Accufab for the last 16 years. We manufactured Throttle Bodies but we also offered RCI headers to our customers (using the Accufab name). I have retired from Accufab but am now working with Craig at RCI. I'm a "header guy". I started in this industry at Kaufmann Products in the 1980's, where we offered RCI headers. From there I started a company with Stormin Norman Gray, and offered RCI headers. I then opened up Pro Mustang Performance, and offered RCI headers. I sold that to Coast High Performance, and while I was there, offered RCI headers, and then to Probe Industries, where we offered RCI headers, and moved to Accufab in 2002, where we offered RCI headers. Over 30 years I have been working with Craig, the founder and owner of RCI headers, and now I'm working exclusively for RCI headers.

There are a lot of thing about headers that people are not familiar with and if you are interested, let's share some knowledge together, and maybe make something useful out of this thread.

George Klass

You guys built mine for me I’m assuming - i believe when I called Accufab I spoke to you . I am almost to the point of test fitting . Tfs20511r head 8.2 deck , aod combo . They are beautiful . My only gripe was they did not drill the centers out for the oxygen sensor bungs . Looking forward to see how they fit. Couldn’t be happier with the construction though . 1 3/4 step to 1 7/8 to 3 in collectors

 

[geoklass]

Yes, you talked to me. All Accufab headers were built by RCI Custom Headers. The reason we do not drill a 1/2 inch hole in the collector when we weld on the O2 Senor Bungs is in case there are any issues with the bung placement and the transmission or the chassis. The O2 sensors have a truly unique thread pattern, and if you ever need to plug one of the bungs up, you will play hell to find a plug. So, we don't drill out the center. Anyone can drill a 1/2 inch hole in the collector, should be no problem.

Your engine compartment is looking great...

George

 

[TOOLOW91]

Yes, you talked to me. All Accufab headers were built by RCI Custom Headers. The reason we do not drill a 1/2 inch hole in the collector when we weld on the O2 Senor Bungs is in case there are any issues with the bung placement and the transmission or the chassis. The O2 sensors have a truly unique thread pattern, and if you ever need to plug one of the bungs up, you will play hell to find a plug. So, we don't drill out the center. Anyone can drill a 1/2 inch hole in the collector, should be no problem.

Your engine compartment is looking great...

George

Thanks bud , I figured I had spoke to you . Makes sense on the bung !!

 

[geoklass]

Now that I'm thinking about it, I'm going to go ahead and discuss the advantages and disadvantages of RCI's Mid Length headers.

The first advantage is they provide almost the same power as the Long Tube headers (assuming that the comparison is with identical primary tube diameter), for less money. The only difference between the two headers (Mid Length and Long Tube) is the length of the primary tubes, the flanges are the same and so are the collectors. Another advantage is they are easier to install, and they weigh less. Another advantage is that you don't need to be concerned about ground clearance.

For most applications, the Mid Length headers are available in 1 3/4", 1 7/8" and also in 2" primaries. We have many racers using the Mid Length headers for all-out racing, some of which run the headers open, with no exhaust system. For me personally, if I had a street car or a street/strip car, I would run the Mid Length header, no question about it, even if my engine was making 500+ HP. For a racer primarily racing in a Dial-in or an Index class, it makes a lot of sense, since you are not running heads-up, you are running on your number. The majority of the street/strip cars I have seen race in a bracket class when they go to the track, and running on your number is what gets you to the next round, and when running a full exhaust, the horsepower difference between our Mid Length and the Long Tubes is not very much, probably between 6 to 10 horsepower at most, and all at the top end.

The thing you have to remember is that the RCI Mid Length header is NOT a Shorty header, it has a full length race car style collector.

When thinking of the disadvantages, the main one is that there is no room to build an effective step-header with the Mid Length headers. By the way, even though we build step-headers for the Long Tubes (1 3/4" to 1 7/8", or 1 7/8" to 2"), if the customer wants them, I honestly think they are over-rated. In my opinion, I don't think the horsepower gain (if any) is worth the added cost.

 

[geoklass]

I might as well get the Front Exit headers (for FOX Chassis Mustangs only) out of the way.

A recent addition to our header line (only about a year in production), we build them in the same diameter primaries as the Long Tube header (and at the same price, too). The price alone is the main advantage, when compared to what others charge for Front Exit headers. Maybe I'm a little old fashioned (okay, I am old fashioned), I can't see much if any advantage in the Front Exit headers, with the possible exception of getting the exhaust away from the transmission. I will probably get in trouble for saying it (and it's just my own opinion) but it almost feels like the Front Exit header thing is a fad, kind of like the chrome coffee can size tail pipes on Hondas. Performance wise there is probably no disadvantage to a Front Exit header compared to a Long Tube or a Mid Length header (I don't think that exhaust pulses know if they are going toward the front of the car or the rear of the car). The mandatory requirement to use a front motor place could be considered a disadvantage for some guys. The standard location for the motor mounts gets in the way of the header primaries when the pipes are aiming forward in the car.

I guess that's it for now, feel free to contact me at any time, even if you are just interested in info for your application, I've listed the phone number, email address and website a couple posts above this one. Also, just in case I'm away from the phone, please leave a message with your phone number and I will call you back. We have continued to be busy, even in the 4th quarter, usually a quiet time for performance equipment. The average order placed today would not ship for at least 4 to 4 1/2 weeks.

Regards,

George

 

[geoklass]

Speaking of header designs...

I think this might be where it all started, original headers for the Ford flathead V-8 engine.

This is an example of the typical hot rod "fix" for the flathead Ford engine, some nice tubular headers. Note that there was no "collector" as such, the primaries flowed into a single pipe on each side, and then into the exhaust pipes and mufflers. For those of you that may not be familiar with the flathead engine, the center exhaust port was "simeased", with the two center cylinders flowing into a single exhaust port.

At the time, headers with actual "collectors" did not exist, but if they did, this would have been a superior design.

 

[geoklass]

Speaking of collectors...

This is not a collector.

Neither is this.

Or this.

A chrome plated non-collector collector.

The people that built these headers knew that they were not collectors, they were built that way to beat NHRA at their own game. There was a rule in the NHRA rulebook for the Gasser classes and the Street Roadster classes, that open exhausts are permitted, but on a V-8 engine, there could only be one exhaust opening per side. A lot of the racers in those classes wanted to run straight open pipes, eight pipes per engine, four on each side. NHRA said "no, no", so this is what the racers did. They used a large piece of tubing, not as a collector, but as a way of covering the ends of four pipes to make it appear to be a single outlet on each side. After a few years of that silly rule, NHRA threw in the towel and permitted open exhaust like on the rest of the competition vehicles used.

This one is good for a chuckle.

 

[geoklass]

Eventually, the factories got into the act and produced OEM headers that did offer better exhaust flow, at least they were better than the OEM headers that were on the Ford Flathead. These cast iron headers would be worth a lot of money today, they are from the first edition of the Ford 289 Mustang Hi-Po engine. Note how the castings are thinner near the bolt holes on the flange. Actually, the casting is not thinner, it's the hole inside the casting that is smaller. This is because Ford small blocks have a 2-inch center to center bolt spacing for each port. This is a restriction, and every OEM standard production Ford cylinder head (and many Ford aftermarket cylinder heads) have this issue. It can be a problem with tubular headers, too, which is why many aftermarket cylinder heads have an "optional" bolt pattern available. When RCI builds headers, we always use a flange to take advantage of the optional pattern (either a wider bolt spacing or a diagonal pattern) if the customer has a head with the optional pattern.

Here is an interesting header designed by Mopar for the 426 Hemi engine. It's a 4 into 1 design, but the "1" is not a true collector as such. There is no way to take advantage of scavenging in a design like this. The tube that looks like a backward letter "C" connects both headers together (like an H-Pipe) and the tubes on the far right of the photos go back to the mufflers. Most of the 426 Hemi S/S racers I talked to felt that the primaries in this design were way to long, that and not having a true collector hurt power. Most went with the more typical header designs (long tube or mid-length headers) offered by the header makers.