Dude you are an idiot.. read the entire post. Less diameter = higher velocity = low end.. Larger diameter = lower velocity = high end. You have it ALL backwards and have NO clue what anyone is talking about including yourself.

I have been here for awhile and get along with most people.. they are not ricers, but you are. And you know it.

And there are many headers avail for the "5.0" otherwise known as 302 otherwise known as small block ford. You can get 2" primaries if you want into a 4" collector. And I am not even sure if you know what a primary on a header is.

nice way to contradict yourself which of course would make you the idiot.

oh finally you catch on to what i've been saying(well you got it partly right anyway) and then somehow try and turn it around like thats what you've been saying.

sorry a ricer would just sit here and act like your the all knowing cause you have a fast car, i on the other hand wont let you spread obvious bullshit.

and i dont give a crap what headers are available for the damn 5.0, but you look real smart cause you were able to remember how many cubic inches a 5.0 has, very good you get a gold star.

Guy's this is a good discussion, but we can do without the name calling...don't get this thread locked.

Don't worry...I'm through debating this. You know the old saying, never argue with a fool...people won't be able to tell the difference.

Exactly

so v8 are you really that blind that you cant see your TOTAL contradiction, which proves you dont know what your talking about???

way to take the easy way out of a debate.

GT40's thinking: some velocity is good, not too much though we dont want the air moving too quickly.

v8's thinking: low velocity = low end power, no wait high velocity makes low end power... no hold on low velocity makes high end power. duuurrr i'm not sure :banghead:

does that about sum it up?

maybe this(your lack of knowledge) is why you hang out at a small honda website rather than debate on a site that actually has v8 cars or better yet a large honda site where theres plenty of people not afraid(hello hstuners are you there?) to have a little debate.

Oh...my apologies for not wanting to continue a debate with some who is obviously wrong and refuses to admit as much. But I'm sure in all your years of schooling in automotive theory and practice that your knowledge has far surpassed my own. What's that? You HAVEN'T gone to school for such things? Well...you'd never know it by your pompous know-it-all attitude. As for "taking the easy way out", you yourself said (and I quote) . I had this discussion with one of my professors today who's been racing, wrenching, and teaching for the past 50 years. His response to your theory of CrAZy L0w 3Nd Fl0w= Mad L0w 3Nd P0W3r..."that's one of the most uninformed things I've ever heard". He then went on to sarcastically comment that if that were the case then everyone would just pull their headers off altogether and run around without any exhaust. So call it taking the easy way out...you're wrong...you can't prove to me otherwise...but I'm not going to argue about something I know I'm right about with a fool who thinks his garage tinkering is in any way equal to my actual education.

that was before the whole thing really got started, but now its going so dont wimp out now.

either you didnt really ask this knows everthing, done everything, or you asked it wrong or he's just about as dumb as the manager over at midas.

the reason you dont run with out a header is that with out it you couldnt take advantage of exhaust scavaging that a properly designed header allows for(get this it HELPS INCREASE THE VELOCITY OF THE EXHAUST GASES) now i know this sounds crazy to a highly educated man(what are you in your first year?) as yourself but its true.

here's another way to put it, read it slowly and let it sink in:

"In order to understand how the merge collector works, you must first know why one exhaust system can generate more torque and horsepower than another. The ability of a header/exhaust system to maintain exhaust gas velocity has a tremendous impact on realizing maximum torque and horsepower. Any significant changes in the system such as baffles (mufflers) or collectors will have an impact on exhaust gas velocity. The large area change seen at the transition from the primary tube to the collector causes an immediate reduction in exhaust gas speed. This reduction in speed decreases the efficiency of the system thereby reducing scavenging ability. Scavenging ability is the key factor to which an exhaust system is evaluated. The more efficient the system, the more air/fuel mixture that can be pulled into the combustion chamber. Obviously, the greater quantity of air/fuel mixture that can be burned, the more torque and power potential the engine has."

copied and pasted from dynatech's website.

copied from magnaflow's website for your reading enjoyment:

BACKPRESSURE = TORQUE?
An old hot-rodder's tall tale: Engines need some backpressure to work properly and make torque. That is not true. What engines need is low backpressure, but high exhaust stream velocity. A fast-moving but free-flowing gas column in the exhaust helps create a rarefaction or a negative pressure wave behind the exhaust valve as it opens. This vacuum helps scavenge the cylinder of exhaust gas faster and more thoroughly with less pumping losses. An exhaust pipe that is too big in diameter has low backpressure but lower velocity. The low velocity reduces the effectiveness of this scavenging effect, which has the greatest impact on low-end torque

and some more, this time from yawpower.com:

Velocity refers to the speed at which the exhaust gasses are travelling. The exact speed is not important to this discussion, but an uderstanding of how velocity affects exhaust flow is. There are two ways that velocity can be increased. One, by decreasing the cross sectional area of the orifice that the gasses are flowing through. (Making the headers or exhaust ports smaller) Two, by increasing the volume of air that is flowing through the orifice. (Increasing engine rpm) Velocity will increase proportionally with an increase in rpm. In other words, if you double the rpm, the velocity will also double. Velocity is inversely proportional to an increase in cross sectional area. Doubling the cross sectional are will halve the velocity, and halving the cross sectional area will double the velocity.

Velocity is important for one simple reason. Inertia. Websters dictionary describes inertia as "The property of matter by which it retains its state of rest or velocity so long as it is not acted upon by an external force." In other words, once it is moving, it will continue to move until some external force stops it. If you apply this theory to the gasses in the exhaust system you can see that once they have been accelerated by the pressure in the combustion chamber, It will take a given amount of energy to stop them, and even more to cause them to reverse direction. Since energy equals mass times velocity squared, you can see that doubling the velocity of the gasses will quadruple the amount of energy required to stop them. This is important because the flow of exhaust gasses is not steady. During each exhaust cycle, the gasses are accelerated, and decellerated rapidly. Often in the forward and reverse direction.

just a little reasoning behind exhaust wraps from autospeed.com they seem to realize the benefits of high exhaust velocity:

High Energy Exhaust Wrap is woven from the finest insulating materials available, and can withstand temperatures in excess of 600 degrees Celsius. When wrapped around engine exhaust pipes, the High Energy Wrap can reduce under bonnet temperatures by as much as 80%, preventing heat related damage and helping to increase horsepower by reducing intake temperatures. High Energy Exhaust Wrap keeps the exhaust heat inside your exhaust pipes to maintain exhaust gas velocity, increasing combustion chamber scavenging and therefore horsepower.

some more about header wrapping and its benefit to exhaust gas velocity from srcinc.net:

Wrapping the headers also serves two other important functions. Low rpm engine performance will be increased due to the higher exhaust gas velocity. This is due to the fact that cooler exhaust gas temperature result in a smaller exhaust gas volume and resultant lower exhaust gas velocity at any given engine rpm. Because both intake and exhaust valves are open at the beginning of the intake stroke, exhaust gas reversal can occur at lower rpms thereby reducing engine performance.

hey these people want to slow down the velocity to eliminate "jet effect" (thrust) from the exhaust of a turbine generator:

Perhaps the most important part of the entire power train is the expansion bellows. Since there is very little practical difference between a gas turbine and a jet engine, the expansion bellows employs Bernoulli's principle to decrease exhaust gas velocity and therefore eliminate jet effect at the turbine exhaust. Without this expansion bellows, the turbine would impart undue thrust against the remainder of the unit. The exhaust gases are now at approximately 1000o F., and are routed by the exhaust bellows into the second section of the train, where thermal energy will be extracted by the heat recovery system

hmmm Borla's got the right idea(copy and pasted from thier website):

Velocity and uninterrupted flow are the real performance-making factors

someday you may ask yourself why do headers sometimes have a special coating??

well HPC(high performance coatings) has the answer:

Performance gains from increase exhaust gas velocity, improved airflow, and reduced ambient under hood temperature

micron exhaust systems(some bike company) also seems to under stand, from their website:

The end result is a stronger pressure wave for scavenging and minimal loss of exhaust gas velocity, both of which translate to MORE HORSEPOWER!

All that just to miss my point entirely. Of course velocity is important...but by your logic, as I said, a totally unrestricted exhaust would be the best way to go. This isn't the case. Ok...say you still want to take advantage of scavenging...why not just run straight headers and no pipes? This works well on RACE cars but not on street cars since racecars could give a shit less about low end power. This taken from "How To Build And Modify Intake And Exhaust Systems":


I honestly think you've ignored most of what I said and are just one of those people who like to hear themselves talk. Go around and quote all of the exhaust manufacturers you want...most of what you posted doesn't really refute what I've been saying and you also have to take into account that they'll say anything because they make the assumption that dumbass wannabe "tuners" won't know the difference. This is the same reason they tell you that you'll get 20hp from a header swap. As for my professor...that's right...keep comparing people to Midas employees. Especially a guy who's spent his entire life around cars. The funny thing about it is that I'm sure that most Midas employees would dwarf you in their mechanical knowledge.

Please please please AzCivic.. go slap on 4" dual no muffler exhaust and see what happens.

Of course less restriction is better to some extent. Why don't you see any of us running open headers? The only real reason to do it is the badass sound they make uncorked. Why don't I slap on a 1150cfm dominator carb? maybe 2 of them with a sheetmetal tunnelram intake? maybe race ported and polished large valve heads?? You just don't know a damn thing about motors. Not that I know all that much, but my sister knows more about an engine than you do. Nobody cares what you do with your car.. I can see now that you are simply bitter towards the 421 header because someone knew you were a ricer and knew you would believe that the $500 header you bought would give you 40hp when it maybe gave you 5 hp.. please leave the big boy stuff to people over the age of 8 and stick to painting your interior like a mcdonald's restaurant, and your single windshield wiper.. thanks.

nononoNO! wtf dont you understand, I NEVER EVER said a big ass exhaust is best, omfg i cant believe your throwing out shit and saying thats what i said. I SAID VELOCITY IS IMPORTANT, YOU DONT GET GET VELOCITY WITH AN EXHAUST THAT TOO DAMN BIG, holy shit did you skip over everything i wrote.

VELOCITY, VELOCITY, MOTHER F'ING VELOCITY.

you said a little is good, too much is bad. I said NO, velocity is key to making power.

and i dont even see why you keep posting you have about as much knowledge on the subject as a ricer that you keep talking about, is it that you used to be one or are one for that matter just with a different car. i wonder if your chevy has gay ass MSD stickers, and a calvin pissing on a Ford symbol.

and please dont tell me what i think and what i do with my car, most people on here know my car isnt rice, so shut up. and if your sister knows so much maybe you should ask her for advice before posting on here.

Look...I'm not argueing that velocity is a bad thing. But you have to take other factors into consideration. Things like volume and pressure waves. Say you have a given exhaust that has a super high velocity. At a lower rpm this could be beneficial under the right conditions. The problem is at higher rpms it will become problematic as the pressure waves will begin to basically run into each other causing them to back up. So you can't design a header around low rpm velocity. But then again you can't design it around high rpm power unless it's a race header. This is especially important with small displacement engines like Honda's since they can't really benefit from an H or X pipe that can even out these waves in a true dual exhaust system. So what do you you do? You design a header whose purpose is to give decent flow and velocity down low without over doing things but has the capacity to flow more at higher rpms. It's all trial and error I suppose but the velocity on the low end can't just run rampant or else you won't have the benefits that come with higher rpm power. I'm also a bit curious...a few posts back you said that even though your 4-2-1 header didn't make the power you desired, other designs did. My curiosity stems from wondering why you'd stick with an inferior design if other products work better. Hell...I've swapped heads on my car 3 times because the pieces I bought didn't suit my purpose well enough...so why should I stick with them? I'm talking practicality here...not balls to the wall power. We're talking about a street car that can't benefit from the logic of race cars that can throw caution to the wind.

Azcivic doesn't know shit.. any one ting you do with your car will affect all other components. He's the typical guy that would put a tunnel ram on a stock 305 chevy and wonder why it runs like shit.

now your repeating what i've already said.

the reason i haven't switched to anything else was because originally i planned on going turbo, but now money is becoming a concern so i'll probably just go with nitrous, and switching to a different header that'll benefit an extra 4hp on top of the 2 i got from the first one isnt cost effective.

and i guess we should all trust you? your dumbass cant even get what YOU'RE saying straight.

Yea I typed the last thing backwards.. sorry but yo know what I meant.

Yea I typed the last thing backwards.. sorry but yo know what I meant.

Wow..what a flame war. But thanks for the advice. I'll probably end up getting the 4-2-1. It won't totally kill my high-end will it? Because that's where I shine when/if racing down the freeway.

- Dzur

It won't.. just won't get as much as with a 4-1.