Thread: Let's talk headers

I am in the process of building a new header and would like to go over a few figures. I have purchased the PipeMax software to help me go over some figures and make some calculations. I am in the process of modeling my header to see where I am starting from. My dyno graph shows my max HP at around 7400 RPM, if I enter this into the calculator, the overall length of the header should be 28-30 inches long at 1.75-1.875" diameter. The Mazworx header I am using now, is 37" long and 1.75" in diameter.

In order to get the program to calculate a header that length, the peak HP has to be set to 6000 RPM. So the calculated peak HP and realistic HP difference is 1400 RPM. Now the question is, does this scale up? I know this program does not take the intake plenum and other parts of the motor into consideration when calculating these numbers.

I am trying to build a header with a peak around 8000 RPM, using the calculator, I get a header at 25-28 inches long.

Anyone have any insight on this? I know a lot of the high HP headers are in the 23" range, so maybe the data is not that far off. I am just a little confused on the results of my current header.

Send in that stuff to Burns Stainless (newest link I could find, used to be different than I see the current scheme presented at this new hyperlink) and they are supposed to give out free quotes... maybe that is the days of past. That is how we got the infamous Kojima header (for DE).

I have been doing some research and calculations to try and decide on some specs. Charles sent me a good bit of info as well that influenced a last minute change. I now have a plan for a header, just need to order parts and build it. Hoping for the weekend of June 3rd to build it. I purchased the PipeMax software, it is pretty good but needs some interpretation but it does a lot of the math for you. I also purchased a book that goes into some detail as well, Engine Math Book.

I will post results and specs to share what I have learned. I am hoping to do some more reading to better understand what is happening and why.

Sooo forget Burns for specs?

I think with Burns you have to purchase one of their collectors to get their specs. All of the parts should be here soon, not sure when I will have time, I have finals in a few weeks, so probably after that.

Ahh i see. dang. Good luck with your tests.

if you are intrested you could commission me to 3d print you pieces of plastic with different angles so you can mock up the exhaust without needing to waste metal...



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spoken to bruce @ protech fab a fair bit about headers. he is adamant , based on a hell of a lot of custom work he has done on sr20's, with the 23-23.5 inch primarys are the way to go. not to say that 25-25.5 inch wont work either, as they have with the kojima signature header.

another quote from charles "sr20 turbofreak" a while ago "I have a header with 23" primaries and it makes more midrange than the 26", and 30" headers. i'm talking from 4000rpm+. and a noticable amount. Why? im not sure. "

and unless for all out drag racing, a 2 1/4 inch choke point is the go. a great quote from pat klutch " if you dont change the stroke, dont change the choke". burns proved this with the kojima header.

i recently put a new tri-step 23" 4-1 into play ( 1" 3/4 >1" 7/8>2") , again over 23 inch's. this has lost a bit of low range, but i'm hoping to pick it up on the other side.

I was in contact with Charles when I was designing my header. He gave me a few guidelines to stick with and I formed it around that. Most of the final measurements were dictated by where everything laid out. We started with the last 2-1 merge, then worked on the primaries. I went the 4-2-1 2 step route. Have not been on the dyno as I am still dialing in the tune, but the feels better in the top end and still strong on the low-mid range. I would have to measure primaries to be exact, but we tried to be in the 23-24" primary range with total length in the 36" range. A local guy has one of Charles' 4-1 stepped headers, brand new still, it would be interesting to see the difference between the 2. I prefer a broad power band, and so far, this header seems to do the trick.

This just for your own personal use? Or are you gonna be putting them up for sale when you have the specs that you like?

Branden
aka hawaiiaNX