As the title says, I was wondering which header would be more beneficial to road racing (HPDE/autocross) the low and mid-range of the 4-2-1 or the upper rpm power of the 4-1? I searched but couldn't find anything. Anyone have any thoughts?

 

they both have their benefits.


The midrange if a 4-2-1 will help you got out of corners better, and the 4-1 will help you down the straight.

I would also say it depends on the rest of your motor. You shouldnt use a long intake (like a AEM) and 4-1, because they both have different "sweet spots".

I like all my power above VTEC, because around here, the tracks support top end power (long tracks and few slower turns)

 

There is so much more to it than just the design of the header and tube pairings...

 

but 4-1 is better because real race cars dont need back pressure.. Especially if you have high revin motor!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">There is so much more to it than just the design of the header and tube pairings... </TD></TR></TABLE>

could you elaborate, I'm trying to learn as much as I can from the people who know best. I'm running a B16a (SIR II) with stock airbox, K&N drop in and docting to the front bumper for some fresh air, and a Tanabe SM. Any advice would be most appreciated.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hatchdrvr &raquo;</TD></TR><TR><TD CLASS="quote">

could you elaborate, I'm trying to learn as much as I can from the people who know best. I'm running a B16a (SIR II) with stock airbox, K&N drop in and docting to the front bumper for some fresh air, and a Tanabe SM. Any advice would be most appreciated.</TD></TR></TABLE>

Do a searh in the archived topics about Header, HyTech, or SMS in the Type-R forum, you'll find a LOT of information/debates on which style of header will, and will not work.

Ausitn

 

ummm all cars don't need backpressure. Backpressure is bad no matter if you have a high revving motor or not, yes the Type-R forum has all the info you are looking for and team-integra.net has a lot of good technical information about backpressure, length of tubes, etc.

 

Ummm, actually all cars do need some backpressure. Guess this is why so many dyno tune their exhaust.

Take it to an extreme - think about using a 6" exhaust pipe that has a very, very small amount of back pressure. Certainly not the best set-up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by granracing &raquo;</TD></TR><TR><TD CLASS="quote">Ummm, actually all cars do need some backpressure. Guess this is why so many dyno tune their exhaust.

Take it to an extreme - think about using a 6" exhaust pipe that has a very, very small amount of back pressure. Certainly not the best set-up. </TD></TR></TABLE>

That isn't because of lack of backpressure, its because the exhaust velocity would be very slow.

Backpressure is always bad.

 

You're mixing up "backpressure" with tuning. First, the exhaust needs to be a certain length to accoustically resonate at the desired rpm. Second, as far as diameter goes, it has to be big enough to "not have backpressure" yet with the conflicting requirement of being small enough that the pressure wave traveling down the pipe is pushing and/or pulling the gas ahead of and behind it.

So yes, backpressure is bad, but having none comes at the expense of the header not doing what you wanted in the first place... so you lose power. Too small a diameter and then backpressure is too high... so you lose power. Finding the proper size is where all the time and money go...

 

&lt;tongue in cheek&gt;It all has to do with transient response &lt;/tongue in cheek&gt;

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by granracing &raquo;</TD></TR><TR><TD CLASS="quote">Ummm, actually all cars do need some backpressure. Guess this is why so many dyno tune their exhaust.

Take it to an extreme - think about using a 6" exhaust pipe that has a very, very small amount of back pressure. Certainly not the best set-up. </TD></TR></TABLE>

Wrong, smartass. Try to avoid posting things you know nothing about. You do not ever want backpressure, and it is not the reason an excessively large exhaust is a bad choice.

 

here I'll do part of your research for you, from team-integra.net

"The 2 goals of a header-cat-exhaust system is to:

a) to efficiently remove as much of the combusted inert exhaust gases out of the cylinder.

Remember that burnt exhaust gas is inert or does not combust twice and therefore cannot make power if it is in the cylinder...it takes up space in the cylinder and prevents fresh air and fuel from coming into the combustion chamber to make power.Backpressure pushes already burnt gas back into the cylinder which lowers your volumetric efficiency and decreases the amount of power you make

b) to keep the velocity or speed of the exhaust gas leaving very high.

When high exhaust gas speeds are reached, a wake is created from an exhaust pulse leaving the cylinder head. Behind this wake, a vacuum is created. This vacuum sucks in more fresh air and fuel at cam overlap, when the intake valve is just starting to open and the exhaust valve is almost about to close. Since both the intake & exhaust valves are partially open at this time of cam overlap, header is actually "connected" to the intake manifold & intake port for a brief period. The exiting exhaust gas helps pull in the next fresh intake air & fuel. This is called scavenging. And scavenging is what helps draw in more oxygen and fuel for combustion.

More fresh air and fuel coming in, with less inert burnt exhaust gases occupying combustion chamber volume, makes more power."


your welcome, have a nice day all

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hatchdrvr &raquo;</TD></TR><TR><TD CLASS="quote">could you elaborate, I'm trying to learn as much as I can from the people who know best. I'm running a B16a (SIR II) with stock airbox, K&N drop in and docting to the front bumper for some fresh air, and a Tanabe SM. Any advice would be most appreciated.</TD></TR></TABLE>

Based on that, I'd defitinely go 4-2-1. If you had hot cams, a ported head, and other associated high rpm tuning mods, then a 4-1 would be a better choice. You would lose low end anyway with those mods, and might as well make it breathe on the top end as good as you can with a 4-1.

For a relatively stock engine like yours, save all the low end torque you can. Especially with a B16, which is shy on low end grunt anyway. Go with the 4-2-1; especially if you autocross. Torque is your friend in those tight confines.

Cheers,
-Mirror

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheMirror &raquo;</TD></TR><TR><TD CLASS="quote">Based on that, I'd defitinely go 4-2-1. If you had hot cams, a ported head, and other associated high rpm tuning mods, then a 4-1 would be a better choice. You would lose low end anyway with those mods, and might as well make it breathe on the top end as good as you can with a 4-1.

For a relatively stock engine like yours, save all the low end torque you can. Especially with a B16, which is shy on low end grunt anyway. Go with the 4-2-1; especially if you autocross. Torque is your friend in those tight confines.
</TD></TR></TABLE>

^w-t-f mate?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">There is so much more to it than just the design of the header and tube pairings... </TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheMirror &raquo;</TD></TR><TR><TD CLASS="quote">

Based on that, I'd defitinely go 4-2-1. If you had hot cams, a ported head, and other associated high rpm tuning mods, then a 4-1 would be a better choice. You would lose low end anyway with those mods, and might as well make it breathe on the top end as good as you can with a 4-1.

For a relatively stock engine like yours, save all the low end torque you can. Especially with a B16, which is shy on low end grunt anyway. Go with the 4-2-1; especially if you autocross. Torque is your friend in those tight confines.

Cheers,
-Mirror</TD></TR></TABLE>


Well, I realize this, They don't call the B16 the torqueless wonder for nothing , i just know there is more to it than that. If it was just a question of torque and HP, then I would just look at dyno sheets for different headers and make my decision. I just wanted to get input from more experienced racers.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by granracing &raquo;</TD></TR><TR><TD CLASS="quote">Ummm, actually all cars do need some backpressure. Guess this is why so many dyno tune their exhaust.

Take it to an extreme - think about using a 6" exhaust pipe that has a very, very small amount of back pressure. Certainly not the best set-up. </TD></TR></TABLE>

Wacked2882 beat me too it.

You want scavenging and velocity to suck exhaust gasses out not backpressure to push it back into the next stroke

For exhaust piping size; your 6" example vs. say 3" for turbo setups and 2.25" for N/A, speaks more towards achieving the right velocity & scavenging and not so much towards backpressure. The ID of your piping needs to be tuned for your setup to achieve maximum velocity.... go too big with your ID and you loose velocity and therefore the scavenging that comes with it.

The only reason our cars have backpressure is because of emissions regulations... not that it's a bad thing to have regulations that are good for the environment but they certainly are not good for performance

 

All right, my bad. I was wrong here.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h22avid &raquo;</TD></TR><TR><TD CLASS="quote">

Wacked2882 beat me too it.

</TD></TR></TABLE>

Actually I beat both of you Didn't anyone read my post up above where I said:

"You're mixing up "backpressure" with tuning. First, the exhaust needs to be a certain length to accoustically resonate at the desired rpm. Second, as far as diameter goes, it has to be big enough to "not have backpressure" yet with the conflicting requirement of being small enough that the pressure wave traveling down the pipe is pushing and/or pulling the gas ahead of and behind it.
So yes, backpressure is bad, but having none comes at the expense of the header not doing what you wanted in the first place... so you lose power. Too small a diameter and then backpressure is too high... so you lose power. Finding the proper size is where all the time and money go..."

 

At a corvette race shop, I had some fairly lengthy discussions with some of the shop guys who fabricate custom exhausts. They were talking about how too little back pressure gets negative results in HP. Without some back pressure, it leads to a situation like kb58 described. Guess I misunderstood them?

 

old school V8 fabricators like to say that backpressure is a good thing because it moves the power lower into the rpm band therefore producing more torque in the lower rpm range. the problem with this is that the engine never reaches its peak potential in terms of torque. Yeah the car may "feel" faster because it does a wheel stand off the line, but the actual engine response is of less than its full potential.

 

again, quick with the quality tech fyi

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">^w-t-f mate?</TD></TR></TABLE>

Yeah, yeah. Primary length, tubing diameter, collector design and length, What diameter is the exhaust behind it, etc. etc. etc. Hey, the poster asked a theoretical question, I provided a theoretical answer. Considering the vast majority of 4-1 designs are tuned for racing applications with big huge primaries and collectors, and the car in question is essentially a stock b16, 4-2-1 still very much sounds like the way to go.

If you can show me a 4-1 that puts out better torque and midrange on a stock b16 than current 4-2-1 designs, believe me, I'm all ears. Not heckling here, I'd really like to know.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheMirror &raquo;</TD></TR><TR><TD CLASS="quote">If you can show me a 4-1 that puts out better torque and midrange on a stock b16 than current 4-2-1 designs, believe me, I'm all ears. Not heckling here, I'd really like to know.</TD></TR></TABLE>

And I'm sure I could find a 4-2-1 that puts out better top end than a 4-1.

 

The way aftermarket headers have gone for Honda's in the past few years can we actually differentiate between a 4-2-1 and a 4-1 header? I mean look at SMSP, Hytech, Headertech, DTR, etc. They all use long primaries that are similar to a 4-1 and then group to 2 secondary tubes and then into a single collector. Basically a hybrid if you wish. These are the headers that are consistently making more power than a OTS DC sports 4-1 or 4-2-1, or any other header for that fact. I think header choice these days comes down to budget and turnaround time because the best of the best are so close in design and quality that is hard to pick one over the other.