Yes, turbulence and restriction I'm just saying avoid super tight bends, or if it's a log-type manifold try to avoid cylinders "T-ing" into the main pipe, (I hope that makes sense.)

Here's a pic of a header for a cummins. It has a very compact design and I think something like this would perform very well for you:

 

Oh and as for primary tube size, the rule I like is, whatever the engine would perform best at NA, will work well with a turbo as well. If anything, go with tubing slightly small rather than slightly large.

 

Thanks for the info, it does make sense'¦. although I cannot see the pic. I copied the link and it wants me to log into competition diesel forum. Would like to see it !

This is along my lines of thinking. On the header on the N/A engine I posted pics of I used 1.75 OD tubing. This is because it was easy, the funky shape of the exhaust port allowed for the 1.75 to capture the opening without any extra effort of a squared up stub (if that makes sense) but in reality it is way to big

The cross section of the exhaust port opening matches up pretty close to the cross section of a 1.625 OD tube 16ga (.065 wall) At this point planning on using this this tubing, will 16 ga be a good choice?

Speaking of tubing I was planning on using stainless for the header build but just recently I am somewhat thinking mild steel. Considerations for this are the effort to back-gas the welding process to keep the nasty's out of the inside of the tube, the thermal expansion of stainless vs mild steel, ease of welding/cutting the tubes, and how cheap I can have a mild steel one coated. Thoughts?

(One side note on the coating on the headers in the NA engine in the pictures above, I brushed that on the headers at the beginning of the season and it stayed just like that all year, first time I have used something that actually worked without a real coating process! I know it would not work with a turbo header but still pretty good)

 

Sorry about that.. hopefully this one works. Same header, different pic:


I'm no experienced fabricator, but for what it's worth I think for your purposes 1.625" 16ga mild would be adequate.

 

Thanks for the pic, so that almost looks like there was no collector, it looks like the tubes just merge at the flange. I notice that the header lent the shortest path possible to the 1-6 pair and wrapped the other 2 pair a longer path, makes sense to me from a pulsed flow standpoint.

 

There are tons of sources for buying header parts, bends, flanges etc. looking at Columbia mandrel bend, who has a good reputation ??

 

Header update: I am using 1.625 tube 16 ga for the primary tubes. I am not a professional fabricator and keeping on a budget, so excuse the hillbilly nature of the build. I just hack portions of bends out of a cheap Jegs header kit, weld together etc. Yes it makes for a puzzle looking header with way more welds than necessary.

I am using only a single 3-1 formed collector so the tubes will merge pre-collector as follows: 1-6,2-5,3-4

i will either use a 2 3/8" or 2 1/4" tube into the TH, any opinions on this?


Started with tubes 2&3

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tubes 2&3 top view

trying to keep things tight

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Add tube 1

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Tube #3 with the upturn for the collector and the merge for #4 primary (mid-tube)

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Adding the forward portion of the 1/6 tube, same intersection plan as the 2/5 tube. Now you can see that there will only be a single 3 into 1 collector

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Connecting #4 & #5 to the flange

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that header looks badass bud. the flow looks alittle weird to me but hell you get cool points for it. Plus still compact looking.

 

It does look nice and compact. My concern would be that with tri-y type design is that typically you should increase the piping diameter after the 2 pipes Y together since you're cramming 2 cylinders of exhaust into the same size pipe they came from. Idk much about the I-6 atlas's firing order or if that would matter. Like, is the merged pipe only seeing one cylinder worth of exhaust or will they be fighting to push thru? Either way, its still gotta flow better than a log manifold

 

Any updates on this build?

 

very nice build! im with etxlancer- any updates?? i wanted to build one of these engines a while back but couldnt find any info out there for them. this post has me reconsidering!

 

I don't know where to start, but awesome build. I'm hoping to get a start on building my Trailblazer, but don't have access to a cnc machine. If you could tell me who cut them for you and how much did it cost to do so? I'm figuring a 7-8 pound turbo 60 lb injectors, and upgrade fuel pump; should give my family wagon new life.

 

Hey bud I have a 06 if you still have it can I get a email of the cad program you used??please