COBB Stage II Tune - 12 OCT 18
#16
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Your Moody Diagram is a general chart showing friction and flow. It has NOTHING to do with the design of the Headers, only how round pipes flow better than other shapes.
All of these headers use round pipes and all have OVAL openings because that is the shape they need to be to match up. How they taper from Oval to round is the discussion.
Basic666: If your theory is correct and no one cares what I say, then no one would have bought the headers. Hey wait a minute, they did sell 2 of them...
As far as "feeling" stronger, there is a direct correlation between sound and the feeling of power. No question that these butt dynos are hearing louder exhaust and feeling power that doesnt exist.
I'm gonna go on record now before the dyno tests are revealed...If any of these make more power somewhere in the curve they are going to give it back elsewhere in the curve. net gain ZERO.
All of these headers use round pipes and all have OVAL openings because that is the shape they need to be to match up. How they taper from Oval to round is the discussion.
Basic666: If your theory is correct and no one cares what I say, then no one would have bought the headers. Hey wait a minute, they did sell 2 of them...
As far as "feeling" stronger, there is a direct correlation between sound and the feeling of power. No question that these butt dynos are hearing louder exhaust and feeling power that doesnt exist.
I'm gonna go on record now before the dyno tests are revealed...If any of these make more power somewhere in the curve they are going to give it back elsewhere in the curve. net gain ZERO.
Also it seems like you have problem reading, like i said, another butt dyno from another thread specifically mentioned they heard NO SOUND difference after installing other branded headers. So clearly the design and shape of the headers have to do with its performance, whether its sound or increase in HP.
But ya, keep on preaching like all the other keyboard warriors here like your opinion actually matters.
#17
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Your Moody Diagram is a general chart showing friction and flow. It has NOTHING to do with the design of the Headers, only how round pipes flow better than other shapes.
All of these headers use round pipes and all have OVAL openings because that is the shape they need to be to match up. How they taper from Oval to round is the discussion.
Basic666: If your theory is correct and no one cares what I say, then no one would have bought the headers. Hey wait a minute, they did sell 2 of them...
As far as "feeling" stronger, there is a direct correlation between sound and the feeling of power. No question that these butt dynos are hearing louder exhaust and feeling power that doesnt exist.
I'm gonna go on record now before the dyno tests are revealed...If any of these make more power somewhere in the curve they are going to give it back elsewhere in the curve. net gain ZERO.
All of these headers use round pipes and all have OVAL openings because that is the shape they need to be to match up. How they taper from Oval to round is the discussion.
Basic666: If your theory is correct and no one cares what I say, then no one would have bought the headers. Hey wait a minute, they did sell 2 of them...
As far as "feeling" stronger, there is a direct correlation between sound and the feeling of power. No question that these butt dynos are hearing louder exhaust and feeling power that doesnt exist.
I'm gonna go on record now before the dyno tests are revealed...If any of these make more power somewhere in the curve they are going to give it back elsewhere in the curve. net gain ZERO.
Below is the best pics I could find of the three headers quickly and their entrance sections.
![](https://cimg7.ibsrv.net/gimg/rennlist.com-vbulletin/1336x342/entrances_7f3b05cb466c4fa286af773c9470f078e7578896.jpg)
With flow entrance sections, a nice radius on the entrance prevents flow separation/turbulence/pressure drop entering the tube. A step in the flow and a sharp transition causes the flow separation region labeled as vena-contracta in the diagram.
![](https://cimg4.ibsrv.net/gimg/rennlist.com-vbulletin/803x244/sep_59d4fd640371e06a386ba6b7e396b1e20f56c73e.jpg)
FYI, Vena contracta is the point in a fluid stream where the diameter of the stream is the least, and fluid velocity is at its maximum, such as in the case of a stream issuing out of a nozzle. It is a place where the cross section area is minimum.(taken from wiki). Anytime you take a fluid, accelerate it and decelerate it, there are going to be losses. Long story short, steps in flow are bad. Sharp transitions are bad.
#18
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
In these headers, you can see the expansion steps:
![](https://cimg4.ibsrv.net/gimg/rennlist.com-vbulletin/735x541/steps_5bbcad71f0b3516299be0ba7679ae58951f1ffb4.jpg)
Last edited by spdracerut; 10-08-2018 at 11:54 PM.
#19
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
spdracerut, don't bother wasting your time on him. if you haven't noticed already - the troll acts as if he's super scientific and would settle at nothing less than actual test/dyno results, BUT anytime you counter his opinions with actual facts or scientific information, the troll goes silent
#20
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
4 point 0:
With NO ONE being able to have a tune capable of taking advantage of these parts until recently, how is it that these parts (that were designed perhaps over a year ago before the ECU was even cracked) can make the claim that WHEN the ECU is properly tuned that their part will make much large gains? Again, speculation and hope. Nothing actually showing that these parts will make any more or less HP over stock or with a stage 2,3 or 8 tune.
With NO ONE being able to have a tune capable of taking advantage of these parts until recently, how is it that these parts (that were designed perhaps over a year ago before the ECU was even cracked) can make the claim that WHEN the ECU is properly tuned that their part will make much large gains? Again, speculation and hope. Nothing actually showing that these parts will make any more or less HP over stock or with a stage 2,3 or 8 tune.
Stage 1 is just a tune. A mild tune, no mods necessary. Its conservative.
Stage 2 typically means "Improved Exhaust flow and improved intake." Knowing that a car is going to have improved intake and exhaust, the tuner tunes slightly more aggressively......Ie adding boost and timing.
That causes more exhaust gasses. The Stock flow may not be able to get rid of it fast enough to take full advantage of the extra boost. But when you have added better flow such as Headers, and either catless bypass or sports cats, you get a better scavenge, giving you full benefit of the Stage 2 Tune.
No one needs the ECU cracked, to develop a better flowing header. Just making a set equal length and having a proper collector so that pulses are not colliding, is an improvement. This is enough for me, even if they never had the pretty welds you are so infatuated with. (I promise I won't call your headers ugly. )
This is just basic modding. Stage 1, slight tune. Stage 2 improve exhaust flow and add more tune. It's not my job to prove anything for you. I am not selling anything. These are not my products. I am free to buy whatever I want, whenever I want. You don't have to buy anything at all. No one cares.
#21
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
spdracerut, don't bother wasting your time on him. if you haven't noticed already - the troll acts as if he's super scientific and would settle at nothing less than actual test/dyno results, BUT anytime you counter his opinions with actual facts or scientific information, the troll goes silent
#22
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Two major ways to analyze this: go to scientific principles and data.
Let's start with data. Fabspeed posted their in-house dyno quite a while ago. Let's say you don't trust that. Vektor has posted their early development dyno done at a different shop's dyno. Vektor also had MotoIQ test it and they used World Motorsport dyno. Say you don't believe either of those. The one guy in Brazil who bought headers posted up his dyno results (timewonka on instagram). Say you don't believe a random guy in Brazil, there's scientific principles to go on. Please note every single dyno shows power gains.
Does anyone need a dyno to tell them a catless pipe is going to make more power than the stock cat? No, because it's the basic scientific principle of removing an exhaust restriction on a forced induction car. NA cars do have a bit differently due to acoustic tuning where a bigger exhaust could actually hurt power. But anyways, you don't have to be a rocket scientist to see that the aftermarket headers have flow advantages compared to stock.
#23
Rennlist Member
Thread Starter