Fo Mi Chin Prototype Basic Shell Complete
Posted: Sat Jul 31, 2004 3:43 am
Monday night I welded up the bent-back intake tube and made the tailpipe with its oval slot to accept the intake. Tonight, I got the whole mess welded up. From arm's length, it's actually fairly pretty -- much nicer proportions than my crude preliminary drawing shows.
What I like particularly is the close fit of the intake lying along the tailpipe -- about 5mm gap between the tube walls! And, a nice steel flare formed with a tubing flaring tool. The intake on this one is just 1/2-inch conduit, and also a little shorter in total length than on the Elektra I. The end that penetrates the tailpipe is flattened to a shade less than .5 inch outside width, to streamline it to the exhaust flow around it. And, as Mike Everman suggested, I limited its penetration into the tailpipe cross section to about the halfway point, so it doesn't form too much of a 'pinch' for the exhaust flow rearward.
Up close, it's a different story. The welding of the pipe to the domed nozzle section of the can was some of the most difficult and frustrating I've ever done -- over 30 minutes to fully weld around that joint! Of course, this time included burning and filling in about 7 or 8 little holes in the paper-thin steel dome. The weld is probably basically sound, but is rough and cratered in spots, and the thickness of reinforcement probably varies all over the map. The fillet weld between the intake and tailpipe is much nicer, from having thicker material to work with. That was done in probably ten minutes of less.
The intake lies so snug against the pipe that you just barely see it above the chamber wall when looking dead on at the front end. So, it's really a pretty clean looking machine. Also, there are no engine mounts or frame to clutter it up, yet.
Overall length without spark plug, 26 inches. The tailpipe is 1.25 inch OD, the chamber 2.5 inch OD, just like the Dynajet. Straight side length of the chamber, about 5 inches. Nozzle dome length, just under 1 inch. Total weight right now [spark plug in place, but no fuel pipe, no mounts] is right at 16 ounces, again exactly matching the Dynajet.
Photos next week!
L Cottrill
What I like particularly is the close fit of the intake lying along the tailpipe -- about 5mm gap between the tube walls! And, a nice steel flare formed with a tubing flaring tool. The intake on this one is just 1/2-inch conduit, and also a little shorter in total length than on the Elektra I. The end that penetrates the tailpipe is flattened to a shade less than .5 inch outside width, to streamline it to the exhaust flow around it. And, as Mike Everman suggested, I limited its penetration into the tailpipe cross section to about the halfway point, so it doesn't form too much of a 'pinch' for the exhaust flow rearward.
Up close, it's a different story. The welding of the pipe to the domed nozzle section of the can was some of the most difficult and frustrating I've ever done -- over 30 minutes to fully weld around that joint! Of course, this time included burning and filling in about 7 or 8 little holes in the paper-thin steel dome. The weld is probably basically sound, but is rough and cratered in spots, and the thickness of reinforcement probably varies all over the map. The fillet weld between the intake and tailpipe is much nicer, from having thicker material to work with. That was done in probably ten minutes of less.
The intake lies so snug against the pipe that you just barely see it above the chamber wall when looking dead on at the front end. So, it's really a pretty clean looking machine. Also, there are no engine mounts or frame to clutter it up, yet.
Overall length without spark plug, 26 inches. The tailpipe is 1.25 inch OD, the chamber 2.5 inch OD, just like the Dynajet. Straight side length of the chamber, about 5 inches. Nozzle dome length, just under 1 inch. Total weight right now [spark plug in place, but no fuel pipe, no mounts] is right at 16 ounces, again exactly matching the Dynajet.
Photos next week!
L Cottrill