I'm not going to start an argument and I'm not claiming to be right, however Sanderson short tube headers were recommended to me by the owner of a speed shop who has been building racing engines for over 50 years. His dyno results showed that short tube headers do produce more torque and horsepower up to 3500 rpm, they equal out from 3500-5000 rpm and then long tube header perform better above 5000 rpm.
I went to Sanderson's website where they tested short tube and long tube headers on the same motors and on the same dyno.
Their dyno test results showed the same results.
I was skeptical, so I called Hedman and Hooker, twice and talked with different techs.
Their techs agreed with Sandersons results and even stated that scavenging of the exhaust gases from the cylinder head was equal for both short and long tube headers and the scavenging is a result of having individual tubes of the header itself and has nothing to do with placement of the collector or length of the tubes.
They said the length of the tubes to the collector is what dictates what rpm range torque and horsepower are made.
The Hooker techs recommended the short tube headers for my Corvette because I was concerned about ground to collector clearances and said I would probably be happier with the short tube headers on the street where my rpm will rarely be over 5000.
Again, this is what three different header manufactures told me, I'm not any type of expert and it isn't even my opinion.
I bought the Sanderson short tube headers because of what my research revealed, that their headers have 3/8" flanges, 1 7/8" primary tubes, 3" collectors, 16ga mild steel and are aluminum ceramic coated inside and out. They also gauanteed fitment with my borgesen steering box on my 73 big block.

I have the flowtech 31106flts on my 79; they fit perfectly even with a rack and pinion conversion. They are made of non-stainless steel and the coating isn’t great; I didn’t know to change the ignition timing and carb tuning and the coating cooked off and they started rusting within weeks. Like I said, do a tuneup after installing.


Adam

The principles and even math by which scavenging via wave tuning works is well known and proven; it’s good enough for professional race teams. The primary diameter and length are most important; secondary length next.

The pressure waves travel at the speed of sound adjusted for temperature, then reflect back at a major volume change back the other way to the exhaust valve; the Length determines how many times, the negative pressure waves provide immense suction that evacuated residual exhaust gasses in the cylinder and at overlap can provide suction to accelerate the incoming intake air and increase VE, resulting in more torque. The timing just doesn’t work with short primary lengths, hence long tube, tuned length headers providing more torque.

Shorty headers > rams horn manifolds
long headers > shorty headers on torque


Dyno headers have long straig sections immediately off of the head; the long, straight length helps rapidly evacuate the exhaust gasses and pull it far away from the head (high velocity and helps minimize reversion); “tight tuck” headers are the opposite of dyno and race headers in this regard (probably not a perf improvement).


Adam