Header construction

[squaab99t]

I have been helping a friend build his headers for his big block Chevy engine. Not a Saab, but a great way to learn and apply to my project sometime. We even had Turbo Stephan and Mezzine jump in and do some work.
The primaries are made of mild steel as they are only for engine dyno testing. The final set will be 304. The collectors are 304 made by Burnstainless
The key constants were was to:
Use the correct diameters
runner length
pairing the cylinders to the secondaries
fitting on the dyno stand and around the dyno itself.

We also has some tuning tools we wanted to incorporate into the dyno headers.
Wideband Lambda sensors and pyrometers a few inches from each exhaust port.
These will allow us to phase or trim via the ECU the individual injectors to adjust for injector flow differences, but most importantly runner differences.

As we built these we also had to build tools/fixtures to make life easier and keep us honest.
We utilized a product from Icengineworks to get the runner length correct and eliminate routing interference. These are plastic 1" segments that snap together to create a chain. You can also rotate the parts so you know where to cut the U-Bend for clocking. The kit come in different Center Line Radius (CLR) to match the tubing on hand or you can figure out how much of what you have to order.

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https://vimeo.com/57075933

[squaab99t]

Part 2

As part of the build process we wanted to try back purging with argon while it was welded. I loaned him my bottle and regulator. I built an end plug to feed the tube and an end cap to help keep the argon in, but allow the O2 to escape.
The crack pipe: 6mm Festo tubing, ballcock valve, the small dia pipe is packed with scouring pad material (copper) and pressed into the 2" dia slug. The silicone tube slips on the slug and the tubing, forming a nice tight seal.

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Since all the flanges are the same a simple sheetmetal cap with (5) 1/8" holes for venting. HVAC tape covering the holes to save on gas and keeps it in the tube. As you weld down the length your leaks will be sealed up and then you pull off the tape when you get to the flange to weld.

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The results are outstanding.

A key element to the process was stitch welding the tube and not just starting in one place and working all the way around. About a .75" weld and then move to the opposite side. Back and forth unit it is all done. Mezzanine's farther in law suggested this technique and it worked well. The tubes did not move much if any from their original tacked position. The proof was the collectors slipped back on after welding all four.

[squaab99t]

Final dyno header product all instrumented and safety wired. This is after break in and a few WOT pulls...
The safety wire is there so we adjust the primary and secondary lengths by adding or subtracting length sections.

[Jordan]

wow , not messing around!

[DrewP]

Sweeeeet.

[squaab99t]

wow , not messing around!

Kevin is an all in kinda guy. As he puts it. The exhaust tuning is his turbocharger for a naturally aspirated. The engine Dyno is really the only way to do this kind of tuning effectively. You will get real time data for every change or combination you make and you can make the changes quickly with the engine out in the open. No crawling under the car to change runner lengths.

[Geoff]

Looks real nice. Can't wait to see the final product in 304!

I assume you did some engineering analysis prior to starting construction. Are there any books or websites you can recommend with design guidelines, formulas, etc. to tickle by brain?

[Crazyswede]

what is the yellow tape on the tubing for?

[Jordan]

it's not tape, it's those snap together header-helpers....

[DrewP]

Yeah. Not many photos on their site of the individual pieces, but it's a mockup tool.

Those are way cool.

[squaab99t]

Yeah. Not many photos on their site of the individual pieces, but it's a mockup tool.

Those are way cool.

I'll take some close up of the plastic segments. The colors indicate the different diameters. Yellow is 2.00". Blue is 1.625". They also include a rubber freeze plug type thing that grabs the header flange at the head and the first segment.

[Crazyswede]

Well thats a fantastic idea. I have never seen those before.

[squaab99t]

Well thats a fantastic idea. I have never seen those before.

Icengineworks, not cheap but what good tool is? They do save a lot of time for mockup. The idea is that you mock it up and then order material. This is to save time and cash and not hack up the real material.

simple snap together, but they are all 1" segments so it is easy to figure out if you are equal length.

Flange attachment

[squaab99t]

I think we negotiated a package deal since we bought a set of 2" and 1.625". $350 each kit. Again, not cheap but if you buy a U bend of 321 or inconel that is a $100 bill. You can F' that up real quick with the cut in the wrong place or you bought the wrong CLR.
You can see how joining a 3"CLR to a 4"CLR gives a different effect. Each segment is 1" on centerline so you know your total run is 6". Old skool was to pour in rice or something into the tacked up tube to see what the difference between runners were.

The kit also can also be purchase with tack welding clamps. Very helpful if you need a second pair of hands while tacking. If you have mad skills, unnecessary. Kevin found his when he was all done tacking.

[Crazyswede]

do you calculate the equivalent length when you do "equal length" headers? I mean do you take into account the different flow resistances through bends or do you strive more for physical equal length?