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Thread: Gas tuned pipes under construction

  1. #1
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    Default Gas tuned pipes under construction

    The posted photos are of two new gas pipes for 27 cc & 35 cc engines under construction. Some sections are rolled from .018" sheet steel & some are machined from thick walled steel tubes. Tapered sections are generated from a computer program, rolled in a slip roll, spot welded & then silver soldered. All sections are silver solder in the final assembly making disassembly for modifications possible. These tuned pipes have adequate volumes for 27 cc & 35 cc displacement engine used for oval competition.

    Jim Allen
    Attached Thumbnails Attached Thumbnails PC050002.JPG   P1230004.JPG   P1230003.JPG   P1220002.JPG   P1210001.JPG  


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    Some more photos of what is done to make a tuned pipe. Tapered sections come from computer generated pieces that are printed out to size. They are then glued to heavy paper, cut & then transferred to the .018" thick cold rolled sheet steel. A slip roller is used to roll the tapered sections. I use a shear to cut straight lines & metal snips to cut curved lines. 050" extra material is added where any straight line joint or curved section is to be spot welded with a Miller resistance welder before silver soldering.

    JA
    Attached Thumbnails Attached Thumbnails 001.JPG   002.JPG   003.JPG   004.JPG   005.JPG  


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    Both tuned pipes in the photo would measure the same length from the side of the piston to the end of the flat section. However their tuned lengths are not the same because the tuned length is measured from the piston face to half of the entire length of the baffle cone. They also have very different total volumes which will determine the maximum length & inside diameter of the stinger section. Stinger length & inside diameter will effect the engines operating temperature. Different baffle cone angles not only effect the total volume of a chamber, but they effect the width & amount of power boost obtainable. Notice that the unpainted chamber does not have a flat flex section in its diffuser, but is tapered from its connection point at the engines header pipe.

    JA
    Attached Thumbnails Attached Thumbnails P3060001.JPG  

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    This is what one of the finished chambers looks like. It will be used in a mono hull with a 35 cc engine by Performance Unlimited. The photo does not show the tuned pipe at its running tuned length! This chamber has two sections in the diffuser compared to three in the latest chambers shown.

    JA
    Attached Thumbnails Attached Thumbnails 20170208_152206.jpg  

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    The type of simple fixture shown allows not only straight section ID's but also tapered section ID's to be easily machined to the exact length needed. It is held in a collet & repeats within .0005". Tapered sections are then mounted on a tapered mandrel for OD machining. Stinger & head pipe sections are typically .040" thick while other sections in the pipe are .018" to .020" thick. Thick walled, A 513 - type 5 steel tubing DOM (drawn over mandrel), can be purchased in 12" lengths from OnlineMetals.com. The carbon steel tubes have a uniform grain structure which is a seamless consistent structure. They also come in various OD & ID combinations & make it easy to machine any tapered section if the beginning ID & the ending OD are known. A 513 DOM steel tubing welds & silver solders extremely well.

    JA
    Attached Thumbnails Attached Thumbnails P4090006.JPG   P4090005.JPG   P4090002.JPG   P4090003.JPG   P4090004.JPG  


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    Tuned pipe construction continues with the use of the fixture shown in post #5. The completed pipe shown mounted between centers was silver solder with Aufhauser Silver Alloy #45 & Nokrode Black soldering flux. Mounting the pipe sections between centers, with interlocking sections, gives a chamber that is straight & true. This flux works with all metals, except aluminum, at both low & high temperatures (1000* F to 1700* F) without glazing. The paste should be brushed on all areas adjacent to the soldering joint as well as the joint area. After soldering, any flux residue left can be washed off in hot water with a steel wire brush. I clean the inside of the pipe by sand blasting & washing with hot water. In the photo, the center section is made of A 315 Type 5 DOM steel & both ends are # 303 stainless steel. Notice how smooth the silver solder has flowed over both pieces. White silver soldering fluxes will not give this result!

    Jim Allen
    Attached Thumbnails Attached Thumbnails P4170003.JPG   P4160001.JPG  

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    This is part of the four section diffuser being built. The diffuser will be tapered from the engines exhaust window to the mid-section. There is also a possibility that the baffle cone will have two angles. The section's tapered ID is machined first, then the OD. A .010" deep X .050" wide relief is cut into the OD at both ends before parting off. Matching diffuser & baffle sections also have a similar relief cut into their ID's. This allows the entire chamber to be assembled between centers before silver soldering because all the pieces interlock. Since the wall thickness of any section is .020" to .022", the thickness of any relief area is .010" to "011" thick. This would at first appear to be a weakened area, however silver soldering make these joints as strong as any other part of the tuned pipe.

    Jim Allen
    Attached Thumbnails Attached Thumbnails P4230006.JPG   P4230002.JPG   P4230003.JPG   P4230004.JPG  

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    The photo shows the next section of the diffuser before it is parted off. A .010" deep X .050" long undercut will be machined before the piece is parted off. One more section after this & the chamber will be ready for silver soldering. Notice the heavy, water soaked brown rapping paper inserted "tightly" inside when machining the OD. It changes the chatter frequency & allows the piece to be machined down to a .022" thick wall without any chatter.

    Jim Allen
    Attached Thumbnails Attached Thumbnails P4260002.JPG   P4260001.JPG  

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    Machining of the third section's ID is done with a 3/4" X 10" boring bar. This section has the same .010" deep X .050" wide relief inside to enable interlocking with its mating second section. The OD is machined by mounting the piece between centers because of it's long length (4.100"). After final machining all pieces are shown interlocked for easy silver soldering. Next comes the all steel header & its 5/16" thick steel mounting flange, which are also silver soldered together. No type of rubber "O" ring or gasket is used between the engine's crankcase & the steel mounting flange. There is no leakage at this point!

    Jim Allen
    Attached Thumbnails Attached Thumbnails P4300003.JPG   P4280002.JPG   P4300005.JPG   P4300004.JPG   P4280001.JPG  


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    The final header section, which is also tapered, is being test fitted before final silver soldering. A special aluminum cradle, with clamping device, will be mounted beneath the mid section of the pipe. It will have a soft neoprene rubber nest for the mid section of the pipe to rest in. Several different length center sections have been machined to allow tuning of the tuned length without shortening of the head pipe area.

    JA
    Attached Thumbnails Attached Thumbnails P5010002.JPG   P5010001.JPG  

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