Stepped Primary Exhaust Extractors
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- čas přidán 23. 08. 2024
- These stepped exhaust headers/extractors appear on Formula One engines. They actually work at the very top of the rp/m range
0:06 purpose
0:13 montage00:34 intro the collector
1:21 primary exhaust
1:53 overlap
2:15 stepped primaries
3:10 effective length
came here after the maisteer video
Indeed
still trying to get my head around the idea
Shit .... Me too . I thought I found one far enough down the list 😂
@@vercingetorige400think of sound waves being bouncy balls and the stepped headers being a wall of teeth .... Once that bouncy ball of sound hits the wall of teeth, it bounces back and splits into more bouncy sound waves That are only half the size but are moving twice as fast
So does the sound work in conjunction with a particular firing order?
WELCOME TO THE MAISTEER PREQUEL
My man!! ❤
Came here from Maisteer
same
Got recomended after the maisteer video! 😂
Oddly enough same here
**Warning, headphone users**... Bro decided to start the video at the loudest possible part....
reminds me of 2 stroke exhausts
I love a nice 2-stroke exhaust note. God, I miss the days when those smoky little torque monsters were a dime a dozen.
Same principal, but on a 4 stroke the step is increasing the negative pressure behind the wave. Sucking out the cylinder. You don't want a high pressure wave pushing into that cylinder during overlap. Also like a two stroke the lengths are critical to valve timing.
Ok, but the overall exhaust channel diameter is calculated by measuring exhaust valve. Making it bigger will affect its diameter and further calculations like total exhaust length and total exhaust volume. Plus the merging point is also calculated for certain wavelength and certain wave bounce back. (typical exhaust headers in normal cars are designed for 1/4 the desired wavelength), long tube headers are for 1/2 wavelength, while making a merging point at full wavelength it would take ca. 2m long header for a 5,5k rpm peak wave utilization point.
Interesting theory but sound only travels so fast, and unfortunately it’s not fast enough at high RPMs to really have any measurable effect
When exhaust pulses reach the collector the enter a "low" pressure area as the collector output size is larger therefore velocity "decreases" as pressure drops and creates a reversion wave as the high speed exhaust hits the slower moving exhaust. The collector is NOT a high pressure area and the step in header tube diameter creates an anti- reversion break as it is harder for the air to pass back into the smaller pipe and creates better total scavenging as the diluted exhaust will not be reflected back into the engine due to the collector slowing exhaust speed but increasing flow per cylinder. Sound effect and flow effect of headers are not the necessarily the same thing and are accounted for differently.
Where do I go to learn more about this? Step location, size of increase at step, number of steps etc.
This would be contrary to Bernoulli’s Principle. Velocity decreases and pressure INCREASES with larger diameter. Friction decreases allowing more flow and the density of a compressible gas increases resulting in less BACK pressure and greater efficiency of the larger diameter pipe. The video is correct.
Everyone’s gonna think the F1 cars are in town…
…me driving my daily subie with stepped headerszzz
Excellent explanation 🙌💥💥
Endyn for the win!!
It’s like what makes a 2 stroke work like they do but a valve controlled version. 😊
I wonder how this thing will sound in a 4 bangers...
Maisteer sent me
Can these pulse waves cause harmonics damage to valve train long-term ?
This is a special edition ❤
Isn’t this similar to a two stroke expansion chamber?
Can you make multiple steps in the primaries, or do subsequent steps have to be done with the secondaries and/or rest of the exhaust?
So the stepping creates a condition for some kind of acoustic vacuum which helps push out exhaust gasses and also amplifies sound? Did I understand that right?
This stepped header stuff just lets you tune for scavenging at mutiple rpm points. Short header = high rpm. Long header = low rpm.
It's not the opposite ?
Who would have thought expansion chambers on a 4 stroke?
Same principles apply to both. Difference with 4 stroke is merely half the firing frequency, and a moving mechanical valve system.
You R the "Primary Exhaust Gas Whisperer"
when the wave coming back from the splitter hits the step in the header does that also send another wave back out doubling in the opposite way assisting again before its reflected at the cylinder?
Yep. This is how tuned port injection works. You can increase the VE (volumetric efficiency) to greater than 100%. Meaning you can ‘boost’ your engine or in other words, pressurize your intake air.
This uses math to calculate the wave speed based on air temp, air density, and wave speed. Once the speed is known, you can use this to calculate how long your runner has to be for the wave to travel to the end and reflect back. The way to supercharge is to have that pressure wave arrive at the back of the valve the second the valve opens. This creates a pressure pulse that is additional to the manifold pressure and higher than the negative pressure in the cylinder. Causing a greater delta, increasing airflow speed and density. Bingo, you used math to boost an engine.
The issue here is that this length is fixed. And only performs well within a very narrow rpm band. Causing a very peaky performance. (See GM TPI)
And sometimes, the RPM that are frequency multiples get some of the same effect. So if you tuned it for 2000rpm, you would see some increase at an octave above, or 4000rpm. While at other rpm, it is technically possible to revert air back to the intake manifold instead of the back of the valve. This would be bad, obviously.
This might explain my situation. I recently swapped cams in my stroker engine and maxed it out for the most timing to the exhaust for a lumpy cam exhaust note. It's alot louder now. I get lots of resonance at 2000 rpms and once I get to 4000 rpms under load, we'll I almost forget how to shift the car is so loud and nasty and shakes the whole car (I'm used to it now). My exhaust consists of equal length long tube, tuned headers, 3" collector and a 3" stainless steel true dual exhaust all the way back. @@TheDashSavers2022
why would some one chose straight step like on 8sec pic instead of taper step like on 18sec pic?
fabrication? And you have to remember that the inside of the pipe does look different than the outside. But if we think about the sound. The radius of the bend (step if you will) does not matter if the lenght of the sound wave is (if I remember correctly) twice the diameter of the radius. So in header scale it does not really matter. For the flow of the gas it does matter if the pipe is smooth, it generally flows better. But as the exhaust gasses are resonating a bit of turbulance might even be beneficial in some situations. It's way over my head thou.
You can see on the lower pipe it has a belled end flange to make it easier to weld. Stepped headers are very hard to build cleanly by not contaminating the inside o f the pipe.
With very clean metals, very accurate sections mating together, TIG welding and argon back purging (shielding the inside of the tube with argon), you could achieve very good welds and a lack of slag and boogers on the inside of the steps.
Is the the stepped only meant for the headers? What about after the collector? Its hard to find a good welder that can do it 😢
I dont know much but from maisters video it must be done before the collector so each cylinder’s exhaust gases can be amplified once by the step and then again once they reach the collector.
And they sound good
Hard for me to follow because I’m not too knowledgeable, but are stepped headers good or bad for performance?
It's all in engine tuning, or the theory of making the air pump more efficient, given its displacement.
Fixed factors are physics (speed of sound, air pressure, etc), variable factors are the design of your engine, engine intake, and engine exhaust system. What is easily variable about the engine is the RPM. What is less easily variable about the engine is the length, diameter, step location, expansion sizes of the intake and exhaust. That requires lots and lots of testing to optimize the engine. You'd need a dyno as well to observe the changes on a graph.
Wonderful
Are stepped manifolds used with Turbocharged engines?
I dont think it would have any significant effect
Yes. You just have to realize that the turbo or open wastegate ends up being the terminating point to the wave. That's why it's good to have a secondary coming off of the collector before the turbo - but of course the downside is on the street when the exhaust plumbing can cool it'll introduce a bunch of lag until the primaries and secondaries get hot.
And you need to pay attention to the cam.
Are the stepped headers only effective for very high rpm engines or are they effective at RPM seen by street or Autocross type engines.
Headers have to be tested on a dyno (combined with anything else that's changed), perfect simulation require data that's hard to determine, so in the end it's quicker and more precise to test if it's of benefit for the specific combination (as well as where they should be, and a number of other things).
Brilliant
I'm stuck step headers
Anyone else waiting for the daft punk beat to kick in after he is done talking
hana
WOW Ok then on a 1 cylender 2stroke motocrosser HAS AN EXPANTION CHAMBER and thats the exact same reson Now im eyeing my poor little BLUE mazda2 no no NOOOO!!!!!
Guys how would sound a K20 with this stepped header ? like a bike engine ?
I've wondered this, I can't seem to find anyone on CZcams who has done it, I'm sure it would sound like one but it won't rev as high of course.
Would love to see it on a v6. I have heard some v6s that sounded a teeny tiny bit like v12 but lacked that _something_ . It may be the missing piece of the puzzle
Seconding this, I want to hear it on a 4 Cylinder car motor.
@@Mortal_3j4 That *something* is probably an extra 6 cylinders lol
@@fancyfox3602 lmao, true
I want to kno if i do a short tube header an a longtube header on my i6.. will i get the unequal length headers sound like a subaru? Plus would love to add this to that set up heavenly?? Oh.. its a low power e46 bmw.. so power not wat im really after.jus enjoyment of sound shifting gears etc.. an maybe little pwr added wouldnt kill me lol
No. Uneven headers kill a balanced I6. The only way you get tthat good sound and choppy rumble from a subaru is only enhanced by the headers. On an e46/the M5x platform a set of good even length catless headers make way more benefit than uneven length.
@@MarcusPinhow would you achieve that f1 sound on an I6 then dying to build some headers for my n52 now
My harley's exhaust has this, kick ass!
you say sound waves don't for get about the fact the exhaust gases start to cool once leaving the cylinder head.. it's important to keep the gasses flowing at a speed to keep scavenging effective.. at: 100% scavenging you mite make 500 hp..... but at 125% scavenging you will make 562.50 hp.. that's the 5th cycle of a 4 stroke engine...
Nice inconnel f1 exhaust?
This video doesn’t really describe how they work.
You need to press that sideways triangle in the center of the video.
In short. Stepped headers do not cause a high pitched sound. They improve scavenging in the pipe, which when the pipes are all tuned length and put into proper merge collectors with even more scavenging, will make a beautiful sound. Every entire race exhaust ever is built with scavenging in mind, so it's nothing new. Some scavenge better without that design or hence sound. Which is why it had its time and isn't seen much anymore. People like Burns Stainless have known this for years. They have said you could - and they have built one - a header system that is constantly tapered to keep stepping up and up and up all the way along its length. But time and cost do not make this beneficial.
Any sudden change in diameter will change velocity. The change in diameter and velocity creates a pressure wave reflection point.
This design does not change the sound of the engine in any significant way.
All exhaust designs will only produce optimum performance within a small window of RPM due to gas volume and velocity vs pipe diameter and length.
The stepped design, when done correctly, will give a slightly broader RPM range with a higher level of efficiency due to reduced pumping losses and less intake charge contamination due to the pressure wave/pulse/reflection tuning that assists cylinder scavenging.
@@jdoe9518Isn't sound itself just pressure waves? It should have some effect
i like subaru turbo ! small sounds great and power to match some v8 engines = i challange motor bikes and porsches ! - usually win .
🔥🔥🤌🤌
This is not a clear explanation, and there are these awkward silences too.😅
That's where the money is 😅
Wrong.. they are anti reversion chambers
I wonder if it would be worth looking into for a drift car that is staying in the high rpms.