My first attempt at making a pipe cone.
https://www.youtube.com/watch?v=1KFK_0ZGQik
CO

You can’t the bottom flush and do some massaging to get it round?

I've been looking at this convergent cone a bit closer.
It is round but not perfectly. Where the two ends touch and are tack welded it's round-ish but the lips are tough to get perfectly round.
I could massage this cone.
I'm having some second thoughts now and may not toss it in the garbage. Not sure yet.
I am wondering how perfect these have to be ? Maybe try it anyways ? Many pipes on machines you see are dented anyways and the machine runs fine. We are not running for the world championship here.
I'm going to move on and try to lay out and make the second cone (Divergent) .
This pipe is being made with 20 gauge sheet metal.
It's a work in progress.
CO

Here is the making of the divergent cone.
https://www.youtube.com/watch?v=iTxpcPxeaZY
There is a mistake in the editing of the video as I jumped ahead and then back again.
You'll notice it.
CO

I wonder if its not round because they wanted more clearance for heat. Meaning after they had the main section welded up they stepped on it to make it oval then welded the rest up? 20ga should be plenty if not over kill I would have went with 22ga, it does make it harder to weld, I have seen a few drag Banshees that felt like 24ga. but they are always trying to save weight and getting dented is not usually a problem. I have seen some of the AAEN sled pipes that were 18ga not sure why, they are protected on sleds, the welds on AAEN pipes are always nasty looking so they might just use the 18ga because its easier to weld.

Unsure how not being round would effect the sound pressure waves I am not a pipe guy or that into the design aspects.

Pro tip for you as a sheet metal worker, the short side will roll tighter first, stop going end for end with the cone, adjust the roller tighter on the long end than the short end then keep feeding in the same way. Follow me? As the cone gets tighter you can clamp a needle nose vice grips on the small end too pivot off of and the large end will rotate around the pivot point. So you might make a few passes with the grip on then a few with it off keeping the gap where you will be welding more parallel. Hard to explain. I have rolled hundreds of tapers in my career, its something you will get an eye/feel for in time then can anticipate what technique is required at each stage of the forming process. It takes practice but once you see how the metal responds, it becomes instinct.

Another pro tip when welding keep moving the hose clamp closer to where you see a gap, also when welding have a filler rod in hand and on the ready you see a hole forming push the filler rod in like your tig welding. For large gaps you can put copper behind the weld to take the heat and the weld will not stick to the copper. Find some 3/4" or larger copper tube beat it flat with a hammer, back off the rollers and finish rolling it flat as you can you want it as tight to the metal as you can get it, use long C grips to reach inside to clamp if you have some. For filling that blow hole if you have no filler rod use a metal coat hanger sand the paint off before use. You could even use the strip of metal from your double cuts just flatten it out, you wont need much filer.

We made a bunch of 16" 10ga 316L stainless steel pipe and fittings once, straight pipe 4' long 45 and 90 degree elbows then welded it all together in as long of sections as possible then made the final welds in the field, We spent 3 weeks in the shop fabricating then another week in the field installing. What a pain in the ass that 10ga stainless was without a power roll, imagine how hard it was getting the crown out of the weld ends lol. We would tack weld on the inside grind the welds smooth put it back in the slip roller and roll it round as we could then beat it the rest of the way with 2lb hammers. We were tig welding the stainless.

Looking good can wait to see the finished product. Careful of the pinch points on the roller

I follow you on that "roll tighter on the long end" and the vise grip.
I'll try it.
The sheet metal guy on youtube was saying what you are saying about "feel" "having an eye" and "instinct". I know what you guys are talking about. It's just like my trade.
As for that 22 gauge or 24 gauge, I did look at that in the machine shop when I bought this metal. The 22 and 24 is super thin and I didn't want to end up welding with the torch and filler. I don't own a tig machine -- it's not worth spending the money on for me.
As for the copper or brass back stop, I've done that plenty in my lifetime.
These are the only two cones I've ever rolled in my life so I know I got learning to do.
Thanks for the tips.
CO

Hey CO, been a while since I've been on here, good to see hour still at it! I believe most pipes are 1 millimeter thick, on a visit speaking with Bill from Bill's pipes I was told for the race bikes they made them from thinner material and they make more power but are only good for about 1 race as they tend to crack, anyway I have been thinking of making a pipe myself, do you happen to have a spare round tuit you can send me? my plan is to use a pressure washer and hydroform it, then it should only require one cut and rotation, there are you tube videos, biggest thing is to make sure all air is bled out.

??? I'm not sure what you are asking here.
CO

I just need to get "around to it" LOL, I guess it doesn't translate well to Canadian.
just my feeble attempt at humor.

You did well at tricking this northern skillbilly with your southern codes
Wer not very smrt here.
CO

Edit: Posting another video in an hour or two.
CO

I have thought about this as well but I think it's a lot of trouble because the material will have to be very thin and then it would have to be welded shut with NO leaks.
I think you would be asking a lot.
I guess it would be possible to solder it but then how strong would it be to hold that kind of hydro forming pressure. I think you are looking at 1000 psi to 1500 psi.
That's why I took a pass on it.

Video shortly -- 10 min.
CO

Edit: https://www.youtube.com/watch?v=iHNcAjvqTVU
CO

What have I learned ?
https://youtu.be/fFvAJpc0fUY
CO

More things I have learned.
https://youtu.be/ApikHi_yMHo
CO

Progressing on the pipe ---- slowly
https://youtu.be/Z2AE4SdCVlI
CO

Temp fitted.
https://youtu.be/4v0vdk-stqg
That's it for a while until the end of the holidays.
CO

One more vid before Christmas break.
https://www.youtube.com/watch?v=vCsv2meUijI
CO

Pipe is looking good.

scpilot66 suggested I set you up your own world for your projects. Check it out.
viewforum.php?f=204

Merry Christmas everybody.
My own world -- LOL.
I've been told a few times in my life that I live in my own world.
Anyways if you wanted to do that then it's ok with me. I would sure like to see all of my posts that I have "authored" in one spot. Right now I know many are spread around. One of them called "Making an FL350 air cooled to liquid cooled cylinder" is actually located in BS world and another one called "Another big crsah" is suppose to be located in the General section but it's not. The only way you can find it is to use the search box. Yes crsah is spelled that way. I miss typed it when I was in the hospital.
Not sure if it's possible now to collect all of the posts I "authored" and put them in one area.
CO

Take care everybody and happy holidays. Merry Christmas.
CO

Ok the pipe is completed and installed and now I have to make the muffler.
I'll make a new post for that.
https://www.youtube.com/watch?v=Sneljg5GWHs
CO

Making the spiral muffler.

https://youtu.be/c49GY91lOJ4
CO

A couple of pictures.
I have to hang my tool box and lunch box at an angle on the hidden hitch because if it fits flat on the back the transmission was getting hot due to no air flow.
Only thing missing on the pics is my lawn chair that goes across those two hooks above the cross bar.
You can also see a couple of bicycle bags on the down tubes at the back. These are WAY cheaper than those bags for the Honda Talon but smaller. I keep poo paper in one of them in case of emergencies.
CO

Just an update on this homemade pipe.

The pipe that I made was a copy of the one on my brothers machine.
That Engine has been worked and has the eyebrow (cats eyes) exhaust ports, cylinder shaved etc.
The machine that I put this homemade pipe on is stock.

Results:
I noticed right away the Engine was a dog.
It didn't seem to have any bottom end zip at all.
Mid range was bad too.
At full throttle it started to produce but it was still way down in power in my opinion.
I have since pulled it off and installed the DG pipe. It's a noticeable difference.
So when the azz dyno can feel the difference you know the power was WAY off.

I don't know if I should call it a failure yet.
It could be my lack of skill and limited equipment that I have but I gave it a good try.
I should actually put this pipe on my brothers machine as his has the original that I copied but I just don't have time. So for now I won't say failure.

I'm having all kinds of projects dropped at my door this year. It's been crazy.
Everything from welding a custom Aluminum oil pan for a 1960's boat for a local business to cones for their wheel balancer, busted Engine mounts, brake jobs, broken water lines, Chinese go cart repairs.
Going to do a concrete pour tomorrow morning at my buddies shop.
I don't even have time to do my projects but winter is here now so I'll get a chance to build that plastic injection molder soon.
Weather very nice right now but I've been sick for a week so couldn't even go riding. Saw the first fresh snow at the top of the hills here last week. Temps are starting to drop as well as it goes down to the mid 50's at night and high 60' during the day. Suppose to rain for at least a week starting in a two days so that may be it for the year.
Only went for a couple of short rides by myself this year but it was enough to test that pipe.
CO

you may be able to add a straight section to the convergent cone, this may help in bringing the power band down in the rpms you use, start with a few inches, if it helps, cut 1/2" off and see if it is better or worse, if better, repeat until it starts getting worse, then at least you know where you need to be.