Why the 4-2-1 vs 4-1 debate is STUPID

There are a million search results when you type 4-1 vs 4-2-1 headers. This is my take on why this debate is stupid and pointless for almost all cars except old Honda engines.

[marcust]

He spelled secondary “2ndary” 🤯 I’m using this bro 🙌🏽

[Josh-pyin]

It's very simple. Your primary diameter and length determine the exhaust velocity. Higher exhaust velocity equals more power. Headers with bigger diameter and long tubes will slow down exhaust velocity until you are way up in the rpm range.

[chrismagalona]

Another explanation why you'll lose power when your pipe is to big is because with an oversized pipe, "scavenging' doesn't happen.

What scavenging is really is a process in which the rush of exhaust gases is so strong it helps pull more fresh air in the intake valve, thus putting more air to the cylinder.

[dave_ecclectic]

not only can't I understand him but neither can the closed captioning. His drawings suck and he seems to never explain the WHY of the title. His including of sensors makes no sense as you don't need sensors for headers to work. Some cars use Carbs and this issue is not a 'honda' thing but an issue of more torque over a wider band versus more HP at peak.

[peterkenny]

Clearly you know nothing about how an exhaust system works

[makantahi]

i have v8, and intend to make long tube header and it seams easier to weld 4-2-1 than 4-1, firing order is 1-8-4-3-6-5-7-2, (now i ask for right side)what cylindres to weld together: 8+2 and 4+6 and then they together, or some other combination, what is ideal diference in degreas between exhaust pulses: 90/180/270/360?

[karlmoltzan]

4-2-1 headers are also called tri-ys. For an inlins 4 cylinder i agree with you. But on a big v8 theu do make more torque down low. This is because of the extra cylinders an more firings per revolution. Americans have been 6sing tri-ys since the 1950s look up Doug Thorley. He was the master.

[JakeTheCrow]

What it all boils down to is flow. It’s old school knowledge anymore, which is a shame. It’s all in the effort of making what you have more efficient. There is the principles of scavenging, which can be argued but mopar proved it with ram air. Quicker evacuation, less resistance (better flow and heat management), heat is necessary for flow.
You can spend all the money you want on “performance” exhaust and pull it out of the box and there’s a fat weld inside of a flange restricting flow 🤦🏼‍♂️
Do some research, break out some books. And try things for yourself. You will never regret having more knowledge. Expect that you will find yourself addicted.

[robertconcepcion]

Is it ok to remove the catalytic converter if im going to install headers? What would be the effects to the engine when removed?

[findtherightbeat]

Could you please confirm if you have an automotive engineering degree? Additionally, I’m interested in understanding the foundation of your theory on building exhaust systems. Could you provide specific details on the principles or research that support your approach?

[Blenzo]

I have no clue what this guy is talking about. I recommend reading Scientific Design of Exhaust & Intake Systems by Philip H. Smith and John C. Morrison If you actually want to understand exhaust design.

[mohammadyousuf]

please any summery, you prefer 4-2-1 for inline 4 cylinders?

[muftifaizan]

For a 1.6 SOHC engine with stock cam and 3.5 points raised compression to 12.5:1. Upto how much length should the primary 4 tubes of headers be, in both 4-1 and 4-2-1 (and secondary lengths) setups ? Street application. G16b engine.

[nikkologs]

Pwede kaya sir palitan ung mid pipe lang ng montero 2017 . Mababago ba tunog? Papalitan ung stock muffler ng resonator lang

[umarkhan-npou]

What about R18 civic only a straight pipe is added instead of CAT how can we improve power on R18

[glazelg.a]

Sir sa honda civic fd na k20z2 2.0 engine ano maganda ilagay 4-2-1 or 4-1???

[somedude]

my 87 Camry is straightpiped and has the 4-2-1 wildcat headers in it. No cat, Idk how much it increased performance but I think I got better gas mileage from it. Do you think a 1st gen 3s-fe really has any benefit to the cat delete 4-2-1? The engine doesn't really flow that much air iirc lol.

[hishammangadang]

Sir, paano sa Toyota vios gen 3 Dual VVTI 1.3 which is more preferred? 4-2-1 or 4-1?

[johnwoodrow]

This guy doesn't know what he is talking about. The primary difference between 4-2-1 and 4-1 exhausts is the length of the pipes in relationship to the size of the collectors. All changes in diameter create backpressure waves. The choice of design determines what RPM and size of those backpressure waves enter back into the cylinders, and potentially back into the intake (due to valve overlap).
There wouldn't be a modern race bike on the planet still running a 4:1 exhaust. Think about that.

[tonyongtv]

Boss you said on another video that making your exhaust pipe bigger also increases your power, is it because it needs to be tuned also while increasing the pipe size?