What's your opinion on these different styles of headers. I heard that they produce power at different ranges. I am looking at an OBX header, and I have seen pics where they are a 4-1 and some that are 4-2-1. Are all OBX headers one way or another?

Andy

MonteSS86@hotmail.com

4-1 = moves power band higher in RPM range.
4-2-1 = makes power band more even across the mid range.

I think that's right. As for the headers you're asking about, I don't know, but you know how most of the ads for tuner parts are written by someone who writes at an 8th grade level these days anyways. Some ignorant misspellings imo. LOL.

you'll need headers when you aren't running an inline 4 or 6. Until then, you are fine with a header

Originally posted by bullox
you'll need headers when you aren't running an inline 4 or 6. Until then, you are fine with a header

Notice when we use "headers" we are referying to different styles. We use "header" when we are referring to a particular header. Headers is correct when you are referring to more than one. And by the way captain obvious, many straight 6 engines use multiple headers, one for the front 3 cylinders and one for the rear 3. You are welcome for the 6th grade english lesson, SMART ASS!!!

Andy

if your have a intake & a catback.... go 4-1... cos you have no low end left anyway... might as well put that power in the upper rpm range. thats where it counts anyway..

most races your never really below 4-5k rpms...

edit: alright i've been enough of a smart ass already :P

I have an intake, but no cat-back.

Originally posted by bullox
edit: alright i've been enough of a smart ass already :P

It is better to be a smart ass than a dumb shit! I, however, am not sure that you fit in the first category.


Andy

MonteSS86@hotmail.com

but im sure eventually you will get a catback... so just forget about low end :-p

the only way to give our cars good low end power is the bottle

if you have an AT go with 4-2-1 because we can only rev to 64k and the gears are taller so we need more across the band but if your mt go with 4-1 for the high revs

i dont really think the 500k makes a difference

4-2-1 is gonna add power below 4k, 4-1 above 4k... right?

But hears the Difference haveing an auto you can only power brake it so high and even then you start out really low in the RPM Range. and you need that power across the board. With a 5-speed you can laucnh at 4K and never see below that. So i agree with the other post if you have an auto then 4-2-1 if you have a manual 4-1. I think i made a good point

Originally posted by ajna_star
the only way to give our cars good low end power is the bottle

uh, marc? lol thats complete and utter bullshit.



read away, and be enlightened.



the (longggg) summary of header design theory. The gist is this. The headers are supposed to route the spent exhaust gas out from the combustion chamber to the atmosphere. But with good design, a header can -expediate- this process by a process called "scavenging". What happens is this.

1. When the combustion cycle has completed, the exhaust valve opens to let the spent exhaust gas go -OUT- into the headers. The upward stroke of the pistons helps to push the exhaust gas out. The over-simplified theory is that once the piston has reached the top of the rotation cycle (where it will start to go down), the exhaust valves closes and the intake valves opens. Thus the combustion chamber has now been emptied of spent exhaust gases and when the exhaust valve opens, fresh air (mixed with fuel vapour from the injectors) will now flow in. The downward stroke of the piston helps to create a low pressure area in the combustion chamber, encouraging more air to flow in.

2. Those who have gone through physics would know of the fact that air flows from an area of high pressure to an area of low pressure. The bigger the pressure differential the more air will flow (and faster). This is a physical law. The ideal situation would be that the low pressure is at vacumn (i.e. no air at all or totally 0 bar pressure) but that is a physical impossibility. Even outer space itself contains very minute amount of particles so except for artificial lab conditions, we cannot even find a nearly perfect vacumn. What this also means is that when the exhaust gases goes out of the combustion chamber, they will NEVER empty completely. There will always be some residual gas left. This of course prevents perfect filling of the combustion chamber during the intake cycle (and why for normal non-race tuned engines such as the lower tech'ed non-VTEC engines, you can never completely fill the cylinders so each cylinder of a 1.6l 4-cyliner 4-stroke engine will never fill up to 400cc, i.e. the volumetric efficiency is below 100%. They often go as low as 75% or less for the bigger c.c. engines found on the luxury cars like BMWs, Mercs, Audis, etc).

3. How do headers come into the picture ? The combustion sequence of 420A is I recall 1-3-4-2 (I think this is correct but it doesn't really matter in the theory). What we want to happen is that the earlier cylinder helps to fill the later cylinder. How ? Take cylinder 4 for e.g. When the combustion completes, the exhaust valve opens. Let's ignore what has happened earlier. What happens now is that the exhaust gas goes out into the "leg" of the header that connects to cylinder 4. Actually it goes out in a pulse (which contributes to the unique exhaust sound). So when the exhaust valve opens, a huge amount of exhaust gas shoots out into the leg of the header, followed by the rest of the gas. The "tail" of the gas or pulse will never completely finish though so there will always be some residual exhaust gas left. Now, the next cylinder to fire is cylinder-2. The same thing will happen when its turn comes to purge the exhaust gas.

BUT, we can do some 'trick' here.

Recall that header designs comes in 4-2-1 (tri-Y) or 4-1 or a few other fancy designs (such as cross-flow) etc. Why so complicated for such a simple thing which only needs to route exhaust gas to the exhaust pipes ?

Well, the process is like this. WHEN cylinder-4's exhaust gas is expelled, it travels from the cylinder head area down towards the collector (i.e. where two more more pipes of the header merges into one). What happens at the header is that when the exhaust pulse flows through it creates a complementary effect - it helps to "suck" any residual gases that may be remaining in the other pipe/leg that connects to the same connectors, helping to create a very low-pressure condition in that pipe/leg. Visualize it this way.

In a 4-2-1 header, pipes for say 4&2 are joined in one collector (3&1 in another), then they join in one final main collector. What happens is that when the exhaust pulse from cylinder 4 goes through the collector, it pulls any residual gases in the pipe/leg connected to cylinder 2 out as well. It helps to promote a very low pressure condition not only in its own pipe but that of cylinder-2 as well. So what happens is that when this very low pressure condition exists, IF the combustion cycle of cylinder-2 SO HAPPENS to have just been completed, when the exhaust valves opens, the purging of the spent exhaust gases will be more complete (since the leg of the header connecting to cylinder-2 will have extra low pressure). This helps to more completely empty cylinder 2 so that when the intake valves opens, more air can flow in. (actually the theory goes a bit deeper than that. By simultaneously opening the intake and exhaust valves, we can also make use of the exiting exhaust gas to help pull more air in. This is what allows VTEC engines to "overfill" the cylinders, acheiving upwards of 105% volumetric efficiency). This process is called scavenging.

Now the extra low pressure condition in the header leg for cylinder 2 will not exist forever, once the cylinder-4 exhaust pulse have passed, pressure equalization will occur again and the pressure will start to rise/equalize with the other areas of the header. So the critical thing in the design of the header is to make sure that each exiting exhaust pulse helps to scavenge another cylinder so that more air can flow into the engine. With more air, more fuel can be injected and thus more power. This means we need to TUNE the lengths of each leg of the header as well as the location of the collectors as well as the size of the pipes AND the collector, etc. Too large a pipe will lower the pressure of the pulse and slow it down as well so it will interfere with the scavenging process. This is why some 4-2-1 headers connects cylinder 4 & 2 together but others will connect 4 & 3 instead. Also the rate at which the exhaust pulses flows is constant (near speed of sound) BUT the interval between the combustion cycles of cylinder 4 & 2 for e.g. SHORTENS as the rpms goes higher. So scavenging that works VERY well at 3000rpm may serve to INTERFERE at 7000rpm. So, if you simply whack a header from what-not engine into your 420A, you may very well interfere with the scavenging process THROUGHOUT the entire rpm band if the header is a mismatch.




_________
96 talon esi-t
san clemente, ca

as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

I am a senior in my last semester of college to be a mechanical engineer, and I have to say that is a very good explanation in layman's (sp?) terms on fluid mechanics. I am very impressed with your knowledge of fluid flow. By the way, I am looking for a Mechanical Engineering job in May, so if anyone knows of any oportunities please let me know. I would greatly appreciate it.

Andy

MonteSS86@hotmail.com

Thanks for the good info guys. If anyone knows where I can get a good deal on an OBX Stainless header please let me know. TuningDepot.com is out of stock of the stainless header for a few months they said. They only have the ceramic.

Andy

buy the ceramic, you dont want stainless... ceramic helps to keep the heat in... buy some header wrap too... you dont want any of that heat escaping.



>But hears the Difference haveing an auto you can only power brake >it so high and even then you start out really low in the RPM Range.

90% of the races ive been in are from a roll anyway....and i can drop gear in my auto the same as a MT....

i guess its personal preference... personally i dont race really anymore.... i just like to haul ass around by myself for fun.


i really wanna get both, and try both... just to see which gains are more significant

7200 - 6400 = 800 rpm aka >12% more revs. also the mt gears are shorter so it revs easier to begin with. Its all about where you want/need the power. off the line and daily driving rpm range or at peak

i street race every sunday..... raced from a roll maybe twice.. i have a full catback and a cold air intake which robbed me of my low end power. the best thing for me to do is the 4-2-1... reason being is because those fuckin light ass civics are kickin my ass off the line every time and by the time my top end power catches me up the race is over. it is personal preference, however i strongly believe in a well rounded engine. i have the top end.. now i need some bottom end for take offs.

p.s: ive used both but sold them cuz i needed money. i will never go back to the 4-1 just for that reason. they are really good but its just what you prefere.

p.s.s: and for you fucks that keep correcting people when they say "headers" instead of "header".... get the fuck over it. i call them headers and im not gonna change it. imo you can call whatever you want, whatever you want. just because you have your moms dildo up your ass doesnt mean you have to take it out on everyone else!!

I couldn't resist this one...
i street race every sunday.....
Strike 1

but sold them cuz i needed money.
Strike 2

prefere.
Strike 3

p.s.s: and for you fucks that keep correcting people when they say "headers" instead of "header".... get the fuck over it. i call them headers and im not gonna change it.
I am one of those "fucks." The whole principle of this website is to make the people who own these cars smarter than the general populace. You just said, in so many words, "I will be a dumb ass and talk like a dumb ass and I will continue to be a dumb ass forever."

imo you can call whatever you want, whatever you want.
I will call it a header because that is what it is and I am not a dumb ass.

just because you have your moms dildo up your ass doesnt mean you have to take it out on everyone else!!
I don't have anyone's dildo up my ass. If the term is misused frequently enough that more than one person feels the need to correct its usage, then there is a problem with ignorance that is not judged or criticized, but redirected. I own one of these cars too and I don't like being associated with dumb shits who talk like they learned everything they know about cars from Harry or Spilner.

Have a nice days. (<- You see how fucking stupid it sounds when you pluralize shit incorrectly?)

:P

Here are some for cheap.
Buy some exhaust wrap if you're going with one of these.
They work just as well as any other brand.

http://search.ebay.com/search/search.dll?query=eclipse+headers&sosortorder=1&ht=1&sosortproperty=3&sasaleclass=2&from=R10&BasicSearch=

In reality, headers don't make too much of a noticeable difference since our exhaust manifold is pretty well made and the downpipe already has a thick diameter. However, the exhaust sounds more aggressive and it sure does look better than a stock exhaust manifold.

Tip: Use a breaker bar when taking off the O2 sensor.

You want top end power. Less restriction = more flow = higher traps speeds. If you are MTX you can always launch to help offset the loss of torque. Other than that you are a complete tard to race any decently modded car from a stop anyways. lol. FWD plus trying to go too fast too quickly from a stop = mad wheel hop IMO.

josh... omg did you write all that? lol... kick-ass explanation.

but what mods really give you decent low end torque?

*edit*
just so im clear on this... a 4-2-1 header is gonna increase power in the 2500-4000 rpm range right? and a 4-1 header is gonna increase power from 4000-redline...


do any decent companies even make a good 4-2-1 header... ive heard so much bad shit about pacesetter, fitment issues, leakage issues... etc etc

Originally posted by ajna_star
josh... omg did you write all that? lol... kick-ass explanation.

http://hcoc.2u.com.my/header.htm

why dont you read that explanation posted above by someone who im sure is smarter than you.

and tell me, does he call them headers or header??

go ahead and read, dont be afraid to be wrong man, ive been wrong once or twice before too :)

you have yourself a nice days too!!!

p.s: i just installed some reverse glow gauges in my car and they look AWESOME!!!

here's what really matters....from old dyno tests from different headers...they really do jack shit for us regardless of the 4-1 or 4-2-1 design...the average gain for either was in the neighborhood of 1-2 wheelHP..which in the grand scheme isn't worth it...i know i never noticed any difference when i installed my greddy header...the gains aren't enough to waste the $$..unless you want it for the looks..i say save the cash and use it something more usefull like cams/cam gears...much more power to be made from those..

oh and about the whole loss of low-end torque...last i had seen was that it was a bunch of bull as well..i know that even with a test-pipe and 2.5" piping all the way from the header collector i never lost anything down low...car always did and always will have plenty of balls in the low end...regardless of what i did to it..

As in my post above... I agree.
The gains from headers are minimal.
However, they do look good and make the exhaust sound more aggressive. If you plan on going nitrous or s/c, then it might be a good idea to have a better exhaust flow.

As for losing low end power, most people feel they have lost low end when in fact the mid to upper range has gained a significant amount... making it feel like the low end has dropped.

So, if you want some headers... buy any powerder coated or stainless steel ones from ebay, wrap it up with some exhaust wrap, use new gaskets, and make sure all the bolts are on tight. Just stay away from Pacesetters. Once the coating wears off, the pipes will rust apart.

Headers / Header... who cares? We know what we're talking about.