I have some very competent welders on my side over here and I am thinking about building a good high HP N/A specific header for my B-series. I am mainly concerned with the technical aspect of this project ( anti-reversion chambers and such) what if I dont have them and just run a nice step tube tube design? Are they that important, and or will it be a major HP difference between on with and one without? TIA

 

good luck getting info on here. no one on here will help you out. do a search and you will see what I mean

 

lol, ya it seems NA guys are more secretive. maybe because if you're good at it you only get 1 more HP

 

LOL yeah. I don't see why people won't share ANYTHING

 

they wont share cos then they would have more competition wouldnt they.

in my opinion i dont think building an anti reversion chamber will have much effect on hp and would just hinder flow - i think its more down to the right choice of primary diametre and length. stepped sizes should work well - remember to wrap your header up with exhaust insulating wrap - don't want heat soak do we .

 

Does anyone have experience/opinions on good sizes for primary tubes and then for the step itself? I really dont feel like spending 700$ on a header!!!

 

burnsstainless will design a header for you for $100. I do believe that cost is taken out of the cost of a collector should you buy that from them. i'm sure one of them can hop in and tell you for sure or you could just check out their site. http://www.burnsstainless.com

 

1.8L motor 1 3/4" primaries i believe stepped to 1 7/8"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Karterguy13 &raquo;</TD></TR><TR><TD CLASS="quote">1.8L motor 1 3/4" primaries i believe stepped to 1 7/8"</TD></TR></TABLE>

I'd actully use 1 5/8" off the head in my own humble opinion.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asylumxl &raquo;</TD></TR><TR><TD CLASS="quote">they wont share cos then they would have more competition wouldnt they.

in my opinion i dont think building an anti reversion chamber will have much effect on hp and would just hinder flow - i think its more down to the right choice of primary diametre and length. stepped sizes should work well - remember to wrap your header up with exhaust insulating wrap - don't want heat soak do we .</TD></TR></TABLE>

No need to wrap a stainless header. Don't wrap a mild steel one it will casue it rust and crack

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by silly4lude &raquo;</TD></TR><TR><TD CLASS="quote">burnsstainless will design a header for you for $100. I do believe that cost is taken out of the cost of a collector should you buy that from them. i'm sure one of them can hop in and tell you for sure or you could just check out their site. http://www.burnsstainless.com</TD></TR></TABLE>

Thanks for mentioning the service and evryhting is correct but it's 75.00 or free with purchase of collector.


When designing a good header there are numerous things you must take into acount: RPM range motor wll be operating in, valve sizes, cmashaft, bore stroke, etc. etc. there are alot of factors and time that goes into it

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kndaqikEG &raquo;</TD></TR><TR><TD CLASS="quote">I have some very competent welders on my side over here and I am thinking about building a good high HP N/A specific header for my B-series. I am mainly concerned with the technical aspect of this project ( anti-reversion chambers and such) what if I dont have them and just run a nice step tube tube design? Are they that important, and or will it be a major HP difference between on with and one without? TIA </TD></TR></TABLE>

I don't believe the chambers are necessary ask some more specific questions and i will see what i can answer for you

 

A lot of people automatically think larger primaries are better, but they usually are not. The reason is that the major function of exhaust pipes is to carry heat away from the head. When the primaries start out smaller, it means increased velocity, which means that the heat gets away from the engine faster. Not only that, but any scavenginv effect is increased by the higher velocity at the heat.


Many motorcycle headers will have a feduced area from the head for about 3 inches, then they flare out to reduce backpressure. Look at a 2 stroke exhaust. It is small at the head and stays that way for a little bit to get heat away from the head. It then opens up very large.

People think you need backpressure, but that's bullshit. People will state that if you pull the header off and run the car, you will burn valves and claim that it's because oxygen gets to them This is bullshit. The reason they will burn is because you're letting all the exhaust heat out right on the outside of the head and not piping it away from the engine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eLusive ek4 &raquo;</TD></TR><TR><TD CLASS="quote">When designing a good header there are numerous things you must take into acount: RPM range motor wll be operating in, valve sizes, cmashaft, bore stroke, etc. etc. there are alot of factors and time that goes into it</TD></TR></TABLE>



All the info is out there, you may have to pay for a book to get the info.

http://www.sae.org

 

oh dang only $75? that rocks.

start reading some books on exhaust/header design. it's actually kind of fun if you like torturing your brain in the name of going fast.

 

Also checkout http://www.headersbyed.com

 

you can also go to http://www.headerdesign.com. They have a lot of info and you can actually download an application I believe... Supposed to help you design your own headers...?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Engloid &raquo;</TD></TR><TR><TD CLASS="quote">
Many motorcycle headers will have a feduced area from the head for about 3 inches, then they flare out to reduce backpressure. Look at a 2 stroke exhaust. It is small at the head and stays that way for a little bit to get heat away from the head. It then opens up very large.</TD></TR></TABLE>

According to the aforementioned website, they explain that the increase in diameter is to intensify the scavenging wave created by the exhaust pulse. They go further to explain that the increase in diameter causes a greater pressure differential after the exhaust pulse enters that area, thereby increasing the intensity of the wave... (though narrowing the effected rpm range I believe)

Any substance to that? I don't know much about header design etc...

While we're at it, I have a question about the 4-2-1 vs. 4-1 design. I made a couple searches and it was tough for me to find a good discussion on the topic. (feel free to point to a good thread... in fact, I'm surprised I didn't see more. I checked the All Motor forum...)
I've seen a few recent header designs that have a 4-1 config. Any info on the advantages of one vs. the other? Thanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ZhaGg &raquo;</TD></TR><TR><TD CLASS="quote">According to the aforementioned website, they explain that the increase in diameter is to intensify the scavenging wave created by the exhaust pulse. They go further to explain that the increase in diameter causes a greater pressure differential after the exhaust pulse enters that area, thereby increasing the intensity of the wave... (though narrowing the effected rpm range I believe)

Any substance to that? I don't know much about header design etc...</TD></TR></TABLE>
Sure, it falls right in hand with my statement. It gets this better scavenging by increasing the velocity. Air doesn't simply stop and start moving, it has to slow down before stopping. What I'm saying is that the speed of air comming out of the exhaust ports doesn't simply stop at once. MOMENTUM of air movement is very important...like in a 2 stroke engine's expansion chamber. The air moving out helps to suck air into the engine on a 2 stroke.

You can effectively get positive pressure inside a nonturbo engine if things are done correctly. What happens is that the air's rushing into the chambers at a high speed. As the chamber fills, there's a spike of pressure before it would actually push backwards. If you can time everything such that the intake valve closes right at this pressure spike, you get more mass into the cylinders, and therefore, better volumetric efficiency.

Of course, this is all splitting hairs in my opinion. People spend more time with the exact specs of an exhaust manifold that will hopefully get them 4 more hp, but they will just throw on any turbo....when the right one could mean as much as 40hp.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ZhaGg &raquo;</TD></TR><TR><TD CLASS="quote">you can also go to http://www.headerdesign.com. They have a lot of info and you can actually download an application I believe... Supposed to help you design your own headers...?

According to the aforementioned website, they explain that the increase in diameter is to intensify the scavenging wave created by the exhaust pulse. They go further to explain that the increase in diameter causes a greater pressure differential after the exhaust pulse enters that area, thereby increasing the intensity of the wave... (though narrowing the effected rpm range I believe)

Any substance to that? I don't know much about header design etc...

While we're at it, I have a question about the 4-2-1 vs. 4-1 design. I made a couple searches and it was tough for me to find a good discussion on the topic. (feel free to point to a good thread... in fact, I'm surprised I didn't see more. I checked the All Motor forum...)
I've seen a few recent header designs that have a 4-1 config. Any info on the advantages of one vs. the other? Thanks.</TD></TR></TABLE>

I don't believe that intensifying the wave is what needs to be done. by attentuating the the amplitude of the wave you can get the right strength of the reflec ted wave to increase scavenging during the overlap period.
The collector choke point will control most of this along with proper megaphone and reverse cone sizing. While stepping the primary's may increase the intensity i have not seen any hard eveidence. Regardless stepped primaries usually come into play becasue calculations will show that the engine at hand would like a particular size of tube, most often this tube size is not the same as the port therefore you need to make a gradual increase in size up the proper dimaeter as to not disturb the flow of gas through the tube.

 

What about the 4-1 vs. 4-2-1? For instance, there was a fabrication post about a new inconel header. it was a 4-1 design. I think I also saw a pretty intense bisimoto header that looked like a 4-1. Most of the more "common" header designs are 4-2-1 as you all are aware. How does that all work?

 

Well a 4-1 vrs 4-2-1 or Tri-Y set up as it is most commonly reffered to in the racing world, there are a couple things to consider. A properly designed and contrcutced 4-2-1 header can yield the same peak horpower while increasng the midrange and low end. a 4-1 is more commonly used because it is easier to construct and produces good power in a "narrower" RPM range. Thats not to say that you can't get a 4-1 to perform very well in fainrly wide range it will just take some tuning and R & D

The inconel header was something we produced btw i hope this helps

 

Appreciate the response. Thanks.