Building Headers

Croatan_Kid

Croatan_Kid

How's your hammer hangin'?
Joined
Nov 4, 2007
Location
New Bern
I've decided that I want to build my own set of long tube headers for my Silverado. Since I did the SAS with leaf springs, the rear spring mount/shackle hanger in directly in the way of any off-the-shelf header for this truck.

I think I'm going to go with 1.75 or 1.875 OD, 16 gauge tubing. I don't want to go TOO big, but I also want to have room to grow because eventually I'd like to build a 408 stroker. As for now, it's a stock bore/stroke 6.0, 10.5:1 compression, a healthy cam, and it makes 320/350 to the wheels.

I'm planning to keep the very close to equal length and I'm shooting for less than 4" of variance on the primary tubes. Production headers can be as much as 8-10" difference! I'm also thinking my primaries should be somewhere around 32-34" inches long. Planning on a 4 to 1 collector, but forming the tubing in to a + shape instead of having a space between the radii.

What I'm looking for is advice, good places to find formulas, calculations I need to do, and what I can do to get the most out of these things, but still keep them reasonably priced. I've found a few places to get header flanges, but the tubing and collectors are a little more involved and can get real pricey if you're not careful!



Hopefully some of yall can give me some good pointers!
 
I thought about that and I may try to do it that way. Not sure if that would really make it any easier or not. I need to crawl under the truck and take a closer look at what needs to happen. I'll try to take some pics too. As it sits, I think the collector would want to be where my shackle hanger sits.

If nothing else, there would always be the cool factor of saying, "yep, I made those headers!"
 
now to rain on your parade, but even though long-tube, equal length headers may sound cool, a lot of the time the dyno charts prove otherwise-typically speaking, short tube headers will give better torque under 5000-5500 rpm. equal length headers can be tuned for a "reasonance frequency" where they produce power particularly well in one rpm range, often at the expense of losses in other ranges, unequal headers operate with a broader spread of frequencies, which tend to result in a somewhat lower peak, but a broader power spread. if your building a drag car, peak hp at high rpm is great, but in a street, especially 4wd truck application, torque and driveability win every time. 4 into 2 into 1 collectors also are good for low to midrange power, without sacrificing top end power
 
My biggest reason for wanting to do this is getting the primary length in a good range to make more torque and also to get a slightly larger primary size. If I go too big the scavenging effect will stop and the exhaust won't expand like it should and pull itself out the tail pipe. I'd think I can get a set to make more power than a set of 1.625 shorty headers.

I need to get my buddy to send me some pics of the ones he made for his CJ7 with a 400 SBC. They're awesome and it completely changed the sound of the exhaust. He also said it was a big difference in torque from just above idle to about 3000. Then again, he's pushing a lot more power....

I'm still doing research and trying to find any information that I can. Keep it coming guys!
 
Judging from what I've read, and looking towards the performance that you want out of your headers? My advice would be to search the internet for all the headers made for a 408 stroker. Find the one that suits your torque needs for the 408 stroker. Figure out all the material and dimensions. Then build the headers the same as the model you found, all while evading your leaf spring shackles.
 
They'd just be regular old long tubes. Probably 1.875, 16 gauge tubing, etc.
 
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