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what's the performance difference in 4-2-1 headers and 4-1 headers

thx

posted by  Accord_Man

4-2 will give you more torque than hp and 4-1 will give you hp. I dont know why it does this but I think 4-2 it uses the gases enertia to pull the gases.

posted by  CarEXPERT

its 4-1 not 4-2 BTW.

posted by  Import-tuner

4-1 headers are designed for racing applications when you are driving the vehicle at or near your redline point. The 4-1 design header maximizes top end power but sacrifises some low end power. The 4-2-1 header evenly distributes power throughout the entire powerband so low end power is not sacrifised.

posted by  Import-tuner

incase your also wondering 4-1 means the header go directly from 4 pipes to 1 larger collector. the 4-2-1 go from 4 pipes to 2 pipes then to 1. The reason for this is to maximize scavenging.

posted by  Import-tuner

Now my question is this..for V6's or V10's...do they make 3-1/3-1 or 3-2-1/3-2-1...or in the V10's case 5-1/5-1 or 5-2-1/5-2-1?

posted by  NISSANSPDR

hold on lemme go look under my 1000TT's hood, lmao. sorry for that sarcasm, couldn't help it. but damn thats a good question.... i dunno.

posted by  Stem

yeah, i knew what the numbers meant, im not that stupid lol

thx for the explanation

posted by  Accord_Man

it depends on the engine type. But for inline six's the headers are 6-1.http://www.turbocalculator.com/headers/ss_2jz.jpg

For V engines the headers do come off of both sides, so for example a v6 would have 3-1 on the left side and 3-1 on the right side. http://www1.ecxmall.com/stores/americanperformance/catalog/GrandAm.jpg

posted by  Import-tuner

Import tuner, if you install a turbo in a I-4 engine and want to install an EXTERNAL wastegate, do the exhaust manifold need to be 4 tubes into the turbo and there is another tube that go to the wastegate? Im not sure where the wastegate goes in the manifold.. please clarify this for me

posted by  CarEXPERT

Wastegates come before the turbo. The wastegate allows you to use a smaller turbo. smaller turbochargers reduce lag time because they have smaller parts to get moving but while spin to fast at higher engine speeds. The wastegate is a value that allows the exhaust gasses to bypass the turbine blades. The wastegate has a spring that senses to much pressure. When the pressure is more than what you set the wastegate for the valve opens releaving some pressure. If the pressure gets to high this could be an idicator that the turbines in the turbo are spinning to fast, so the wastegate bypasses some of the exhaust aroun the turbine blades, which allows the blades to slow down.

posted by  Import-tuner

I know that but I asked where is it as as in where is it placed. Is it on the exhaust manifold runners? I thought the external just sends the gases to the atmosphere not bypass the turbines.

posted by  CarEXPERT

ok sorry, the external wastegate mounts onto the exhaust manifold then to the turbocharger.

posted by  Import-tuner

Incorrect the size of a turbo is'nt relevant to whether or not you need to use a wastegate. If you're running high ammounts of a boost(20+psi) constantly an internal wastegate will work just fine. When using any turbo setup that produces a lower ammount of boost (6-10psi) you'll want to go with an external wastegate.

Pressure sensing spring? More like a flapper door operated pnuematicly by a mechanical actuator.



More than likely the external wastegates are mounted to the exhaust manifold or to the O2 housing, and are self contained units.

posted by  DSMer

I think he was inferring that with a larger turbo the boost will not be able to achieve high pressures, instead sitting around the surge region. It would operate like a dog, but possibly not need a bypass syatem.

External wastegates are good for efficient turbo combos that would otherwise suffer from creep due to either slightly undersized internal wastegates or bypass and dump(down) pipes and mismatch with the reaction time of the internal wastegate. I'm not aware of any pressure range requirement, rather the rate of rise. Externals can also help reduce boost spike. Standard wastegate actuators are fairly slow on the uptake by design.


Having said that, a well sorted internal wastegate with correct porting and correct waste piping can be be quite acceptable.

posted by  Wally

Quite true, I believe that was the point I was trying to get at. Most people have a belief that external wastegates are somehow "always" better than internal when in fact thats not very true. Again I understand what hes referring to with larger turbos not being able to achieve higher boost levers on most setups but you have to remember I come from a DSM community. Even the largest Garrett turbos put into our applications can see excess of 18+psi on a normal day.

posted by  DSMer

DSMer I thought the external wg can suport more psi than an internal? Cus the external wg is usually bigger in size.
An external wg has 2 holes in it, an outlet and and inlet I think. So the exhaust runner goes into it before the turbo right?

posted by  CarEXPERT

Well you thought wrong(as usual). If you knew the basic operations of an engine you'd know that... That includes turbochargers and turbocharged applications...

posted by  DSMer

So why do factory turbos comes with internal wg? Because they are designed for doing low boost pressure. When you up in the 20+psi then you have to get an external wg cuz it can regualte more boost.

posted by  CarEXPERT

why? probably because theyre just cheaper... and the companies dont really expect to have their stock turbos bumped up to 20+ psi

posted by  mazda6man

Are you asking a question or are you making a point? As I allready said, external wastegates work best for turbo setups producing constant low boost. Internal wastegates will work best on turbo setups where a high ammount of constant boost is produced. The keyword is constant...



No always true. I've seen garett turbos that would have been cheaper to purchase in turbo and external wastegate setup rather than turbo with internal. It all depends on what you're trying to do. It is'nt always up to the motor company to decide wheter or not to use a cheaper internal unit. Sometimes thats what will work best.

Nonsense, I'm sure Nissan and Mitsubishi knew that their motors were capable of 20+psi.

posted by  DSMer

Ok DSMer, then why is it better that way? It doesnt make sense to me cause usually external wastegates are larger and larger springs so they can relieve more psi than an internal.

posted by  CarEXPERT

How about you research the answer to that question and find out on your own instead of pestering me to validate it. You have to remember at the end of the day, I don't care if you disagree with me as long as I know what I know...

So I suggest if you want to find the answer you start making sense of it elsewhere using your own reasearch because I'm not saying anything.. The analogy of bigger is better rarley works with everything that pertains to car functions so you can get that out of your head now. Just because you're trying to move something does'nt neccesarily mean the biggest capacity to carry it will be the better application for the job. You can start with that logical reasoning and work from there.

Pick up a book, read a magazine, do some research at companys that manufature wastegates, or just simply type it in a search engine... Again, thats only if you really want to know...

posted by  DSMer

wow, I've never heard truer words. still, I've learned a lot in my 5 months here, but not by asking everyone every single question that pops into my brain. howstuffworks.com helps a lot also.

posted by  Godlaus

Sad thing about him is that he'll never suceed in life with attitude. I can almost 100% garauntee that he did'nt go research and learn the information and that is what makes him a failure in the automotive world. Not because he's stupid, not because he lacks knowledgable information. Its because he is too lazy to take advantage of easily accessable information literally at the tip of his fingertips. Like Wally said, Don't waste the oppurtunity to learn something that has taken thousands of years and billions of lives to aquire. If it theres take heave, because knowledge is power. Sad as it is he just does'nt have the ambition to want to learn.

If that were me about 2-3 years ago and somone mentioned something about a wastegate and I had no idea what it was I would read up on everything about wastegates till 1 and 2 o`clock in the morning. I would read so much information, look at so many pictures until I was no longer able to keep my eyes open. Then I would go out and find physical proof of the object, study it and phsically see how it works. Its those kind of things that got me to knowing what I know today. Wich is still nothing compared to what I will learn. I don't know everything and when compared to whats out there to know about cars I don't really know much of anything (Not being humble Wally just being honest :thumbs: )..

Any aquired skill be it cars, building houses, or making shoes. It is'nt going to come to you sitting on your ass bugging people for information. People don't care to help newbs and when newbs become knowlegable enough to help people they don't want to help newbs. The ammount of valid information on the internet is so vast that there should never come a time when he should ask such a simple question as to why an external wastegate does what it does... Its just that simple, pop open a google and search arround for a few minutes of your day to learn something.

CarEXPERT is'nt smart enough to realize that, nor does he have the ambition to learn therefore I'm not wasting my time with him....

posted by  DSMer

Sorry DSMer, when You said that internals work best for constant high boost, I remembered I read a thing about wastegates in a magazine that said external wastegates can relieve more psi because they are physiccally bigger than internals. But I got it mixed up what you said and when I researched on the internet, I found that if your looking to run high boost all the time 20+psi than an internal wg will be best and if your looking for running low psi than an external will be better.
But I dont and cant find out why and im still trying to find out why is it better like this

posted by  CarEXPERT

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