ARH Headers - emailed them..

[tallboy]

Your exhaust system is designed to evacuate gases from the combustion chamber quickly and efficiently. Exhaust gases are not produced in a smooth stream; exhaust gases originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle, a 6 cylinder has 6 pules and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.

Well...yeah. I'm not sure what your point is. That isn't a counterpoint to my statement at all. If you look at the very next section of the article you are quoting, you will see this:

"Many people mistakenly believe that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this idea would be appealing - as wider pipes have the capability to flow more than narrower pipes. However, this omits the concept of exhaust VELOCITY. Here is an analogy...a garden hose without a spray nozzle on it. If you let the water just run unrestricted out of the hose it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will spray out at a much much faster rate.

The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. (see below) If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be travelling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you also want make sure the pipe is wide enough so that there is as little back pressure as possible while maintaining suitable exhaust gas velocity. "

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[Anthony]

the 11-14's are not a direct bolt in on long tube headers

I am not sure if the kooks mid lengths are the same, and just the mid pipe needs changed or not

Watson used 2014 arh headers on their 2015 sema mustang. Zero issues. Didn't bolt to a h pipe, as arh didn't even have one available at the time.

 

[Bahndvr]

Well...yeah. I'm not sure what your point is. That isn't a counterpoint to my statement at all. If you look at the very next section of the article you are quoting, you will see this:

"Many people mistakenly believe that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this idea would be appealing - as wider pipes have the capability to flow more than narrower pipes. However, this omits the concept of exhaust VELOCITY. Here is an analogy...a garden hose without a spray nozzle on it. If you let the water just run unrestricted out of the hose it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will spray out at a much much faster rate.

The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. (see below) If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be travelling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you also want make sure the pipe is wide enough so that there is as little back pressure as possible while maintaining suitable exhaust gas velocity. "

Would you happen to know what is the diameter of the exhaust port on the head?

 

[tallboy]

Would you happen to know what is the diameter of the exhaust port on the head?

Nope, no clue. Hopefully one of the aftermarket companies here can comment on that.

 

[Bahndvr]

Nope, no clue. Hopefully one of the aftermarket companies here can comment on that.

+1 I hope one of the shops will take the time while they change the headers to take a caliper to the exhaust port and get the dimensions.
I will try and dig out my books.

 

[Bahndvr]

I am to understand that the exhaust port is about 1½" in diameter so I wouldn't go over 1¾" and probably 1⅝" would work just fine. I won't have to dig my books out after all.

I apologize 1320' for hijacking your thread there is a lot of sales persons on here and I enjoy the tech talk.

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