exhaust header tech docs

[SeptemberSquall]

While remaining aware that the hosting site has a commercial interest, there's a reasonable introduction to exhaust header theory and practice here including a detailed guide to manufacturing your own headers, which I intend to try.

http://www.burnsstainless.com/TechAr...harticles.html

http://www.burnsstainless.com/TechAr...ry/theory.html
http://www.burnsstainless.com/TechAr...struction.html

[gemtoy]

That is a very good site for info on exhausts. I just built my own set of 4 into 1 extractors for my 3sge race engine it took me a long time but it is worth it in the end. I used flexible plastic corrigated conduit as my mock up to get all the same length and then bought the mandrel bends to suit the shape. I tack welded the pipes together then I went to an exhaust place to weld them as my welds are not the best looking,but his work was just as rough as mine. So I ground the welds back and it looks better. If you want a picture I will post it up here.

[roadsailing]

post em up for sure,

my plan is to bend each pipe, so i dont have to weld mandrels together, its going to be a big job though.

gemtoy, how is your engine's midrange power?

[mrshin]

Gemtoy, while grinding them back on the outside is alright, if the welds were rough, are they also full of nasty little daggy bits on the INSIDE, where it counts?

[gemtoy]

I have posted 3 pictures. One of the plastic pipe I used to set the length and position and the other two are the final product.

mrshin- When the pipes were butted up there was no real gaps and I got the grinder into the bits that were rough.

shinybluesteel- I have not run the engine so I have no idea of the power band. Bending the pipe from one piece is an even bigger job.I have heard that you can fill them with sand to stop them from wrinkling and heat them up also.

[Fish]

paul i lkove your extractors!!

[crowncustom]

Top job on them.It just takes time and patience to get it right.
Cheers Brett.

[Billzilla]

We built a set of extractors (not headers, that's the US terminology) for my racing car using the single pipe filled with sand trick and it's a right pain in the arse.
We're never going to do it again, rather just use mandrel bends and straight pipe.

(Though the forge and bending machine were fun!)

[SRacin]

Im in the process of makeing.design.construction 20v 16v rwd 4age headers from one piece mandrel bends. Doining it in conjunction with a local bending company who have a CNC mandrel bending machining. Anyway Check out the pics.


the first prototype construction from mandrel bends tacked together




The first prototype's fitted up.



The 2nd one piece prototypes, yet to be fitted and tweeked to get the lengths to +/-5 mm




Logan

[kingmick]

um yeah ok!

[SRacin]

edit.dont wory.

[Enchanter]

I will be embarking on a similar project in the not too distant future aswell, I have found this page to be very good, especially the design calculator.
You need to register to access the calculator it but is free, and I havent recieved any spam/anoying ads etc

http://headerdesign.com/index.asp

Enjoy

[Dimitri]

SRacin. isnt it convention to run the primarys in firing order on a 4-1 design? 1342 around in a circle? yours dont seem to do that? though its hard to see.

[99Westy]

Circle firing is the theory alright.

However lots do not construct in that method... believing that it only makes an insignificant difference to performance...

It definitely does work though!

[SRacin]

You are right mine do note group in the firing order. Does anybody have any tech reference's (or the above links which i havent had time to read in depth yet?) which refer to this grouping theory?

I can somewhat hazard a guess at the benefits, but in the real world the gains are probably three fiths of five eights of sweet f all, and at the end of the day comprises must be made between production, space restrictions etc.

The headers i have posted the pic of will be commerical available for 3-400 NZD's.

Also. Id like to give props (+rep?) to the character who made/helped with the first prototypes.