PDA

View Full Version : Hydroformed exhausts. Expansion chambers and Megaphones



Billy Golightly
11-10-2007, 12:20 AM
Always wondered how they did this, I use to think they were just stamped out and welded together but I now see I was wrong! http://www.eurospares.com/frame8.htm and this one too: http://www.two-stroke-addicts.freeserve.co.uk/mick/hydropipe.htm

Youngrasher
11-10-2007, 08:20 AM
Thanks, Its great to learn little tricks like this.

Bryan Raffa
11-10-2007, 09:45 AM
Thats cool.. I have seen it done with just air

SWIGIN
11-10-2007, 10:06 AM
thats pretty cool

TRITecate350
11-11-2007, 01:42 AM
About 8 years ago, I toured Rick Ritter's shop (RCR) and he hydroforms his polaris pipe. He had stacks of pipe sheets cut out from a cnc plasma. He used a powerwasher to supply the presure needed to form the pipe. Then with the water drained, he would pressure the pipe with air and would heat the seam with a torch and hammer it into shape. Then grind down all the seams and reweld them.

RacerRichie
11-11-2007, 09:10 AM
cool
same here seen it done with air before but not water.

Billy Golightly
11-11-2007, 07:24 PM
Whew, I'd be scared to use air. If one ever popped, it'd be just like a balloon but instead with sheet metal for shrapnel :lol: I dont know the exact physics behind it, but from what I was reading the reasoning for using water was because if there is a leak or something, all the pressure drops instantly and the power/force is dissipated a lot safer then if it was just compressed air. I've gotta try it someday though, I bet it works extremely well.

Aka_am
11-11-2007, 08:25 PM
wow, someone should start making new custom pipes!

gotcams?
11-12-2007, 06:19 PM
Hmmmmm.....I wonder if that technique can be applied to making a gas tank. I'm thinking the seams wouldn't be strong enough to hold that much pressure. An exhaust could, I'm going to give it a shot. Also might want to braze over the welds, might make it safer because brazing is typically used in raditors and repairing hydraulic lines. A weld will hold the metal together with a relative of 60k psi and the braze over that will stop leaks and give it added advantage. Only danger is the metal giving and not the weld, IMO.

But very, very cool!

jeffatc250r
11-15-2007, 01:20 PM
Very interesting read. I never gave it much thought until this. Thanks for sharing!

NOS_350X
11-15-2007, 06:56 PM
hmmm intresting, but every pipe ive ever see is eather a coned sectional or stamped pipe. Never seen one anything close to those

Billy Golightly
11-15-2007, 09:57 PM
Actually this is how the ones that look like their stamped are made. The only ones that are truley stamped are the OEM ones.

Daddio
11-15-2007, 10:51 PM
Whew, I'd be scared to use air. If one ever popped, it'd be just like a balloon but instead with sheet metal for shrapnel :lol: I dont know the exact physics behind it, but from what I was reading the reasoning for using water was because if there is a leak or something, all the pressure drops instantly and the power/force is dissipated a lot safer then if it was just compressed air. I've gotta try it someday though, I bet it works extremely well.

I'm not sure about the physics either but I do know that water can't be compressed like air.

tri-z_250R
11-15-2007, 11:11 PM
I'm not sure about the physics either but I do know that water can't be compressed like air.

If I were to take a guess, it would be that they probably heat the steel to a certain temperature to make a easier to work with, and then they pump water in with incredible force before the steel gets a chance to cool down. It seems strange to me that water could do that.... maybe the water pump just keeps forcing water in until desired shape? They might even have to give it alittle motivation with a hammer?

NOS_350X
11-16-2007, 02:17 AM
Actually this is how the ones that look like their stamped are made. The only ones that are truley stamped are the OEM ones.

I know esr gets there stamps from a company in nor cal, the come curved. From what ive herd. Almost all 2 stroke pipe makers go through them, They give these guys a pipe, they make a mold off of it and make stamps to fit around the mold.

Billy Golightly
11-16-2007, 09:36 AM
Power Pros? The reason I said what I did is because, if you look at all the aftermarket pipes that are not coned sections, you will see they have a weld lines that are relatively flat. I'll use my FMF 250R pipe for an example. Because your only working on one plane, you have cut out and Hydroform the pipe in sections, and then weld it together. Thats where the multiple pieces come in the design. Actually stamped pipes, like a stock 250R one, have an external thin ridge that runs the full length of the pipe, usually like a1/4 inch high. Those are stamped.

Bryan Raffa
11-19-2007, 10:14 PM
Dynoport stamps them out with the curve of the pipe in it .. they just weld it together.. that seems simpler , Im shure that how the stockers are done

XL-erate
01-09-2008, 02:55 PM
Thanks, Billy, excellent info!

DON'T USE AIR!

As mentioned in Michael Moore's article in footnotes, air is compressible, water is not [at the pressures dealt with here]. Most common pellet guns seen today use the 'spring air' principle. A spring attached to a rod & piston in a cylinder is cocked, or compressed. Piston pressure outlet is into barrel, with a pellet in front of piston's air outlet. Pulling the trigger releases the spring, ramming piston forward in its bore and compressing all the air behind pellet. You know what happens next.

Using air to hydroform is similar to pointing the pellet gun at you head, cocking the trigger and hoping it doesn't go off! Because you're compressing the air it builds up and stores kinetic energy, behind the steel, just like a huge spring. A materials or weld failure then ruptures steel and it's just like pulling the trigger, to suddenly release all that 'air spring' pressure and rip metal into shrapnel chunks. Metal fragments are like the pellet. At 1,000 psi you can shoot and kill a deer or human with a single spring-air fired .22 cal pellet, smaller than a pencil eraser. Make sense?

Steel has a modulus of elasticity that allows it to maintain its molecular strength while bending, so this amount of elastic property actually holds the metal's molecules together as if it was in a die stamping form. The water pressure builds up against the interior surface, same as air, but the liquid doesn't compress: therefore no compressed 'air spring'.

Sorry I can't explain it better but bottom line: gas/air pressure accumulates energy and its explosive force can maim and kill; water pressure immediately dissipates only surface pressure, not stored energy. Please, don't experiment with air in this type of project, it's Russian Roulette!

Billy Golightly
02-18-2008, 02:11 AM
http://www.jalopyjournal.com/forum/showthread.php?t=77692

I stumbled across this link on another forum I lurk for their tech (great stuff too) and I figured I'd post it up.

NOS_350X
02-18-2008, 03:49 AM
I realy think that to make something decent will take TONS of work. But The cr500 in my 400ex chassis was going to get trashed because i keep braking pipes. SO im going to try and make me a OOF drag pipe for it. See if it willstay together then.

NOS_350X
02-19-2008, 05:28 AM
i got a quick question, From what your reading do you have to get a pump that will pump only water? If so can i modify the tip on my presure washer? OR can i fill up with water put a cap with a shrader valve on it and preasureize with air??

Billy Golightly
02-19-2008, 08:06 AM
No, DO NOT USE AIR! It needs to be pressurized from start to finish with water only. I suppose you could use a pressure washer, unless its a really big one I'm not sure it'd have enough pumping power to get the job done but it might.

NOS_350X
02-27-2008, 03:00 AM
Ok, well i made up my template for my OOF pipe for my cr500 conversion. Mocked all the same tapers and size of the inframe pipe i had made. Im just going to use a thicker guage steel. going to get it all built and then figure out how to presurize it. Plumbers around here seem to have no idea wtf i could use.

Billy Golightly
02-27-2008, 12:19 PM
Atleast with the pump you can take your time and see where the leaks are before they blow apart. Don't have that ability with the pressure washer, its gonna be putting out an awful lot of water when you pull the trigger.

hondahaulic
03-01-2008, 05:02 PM
going to get it all built and then figure out how to presurize it. Plumbers around here seem to have no idea wtf i could use.

Know any farmers that live near, or someone with a tractor? Tractors have hydraulic pumps that pump oil to raise/lower hydraulic cylinders on equipment. These things put out a great deal of pressure. If you could get a male hydraulic coupler on one end of your pipe, I would bet it should work. By doing this, you would be using hydraulic fluid instead of water.

heres a link to a pic. of the couplers i was refering to. http://www.snap-tite.com/snaptite_QD/products/interchange_couplings/60_series/images/L_60s.jpg

NOS_350X
03-03-2008, 04:17 AM
I have a tractor with a front loader, and the hydraulic pressure it would push in would be WAY too much. Need a handheld hydrulic pump.

money89tractors
03-03-2008, 08:05 AM
Reason water is used over air is because water/liquids dont compress. Air would simply make these pipes a small air tank with very thin walls and ready to explode. Water will simply push out in all directions without compressing.

Someone mentioned making a gas tank this way. It could be done. Biggest problem with it is if you want a flat panel on the bottom. You would have to make any flat areas out of a thinker steel to the rest of the metal will "form" to shape before the flat areas begin to "form".

-Phil

Dirtcrasher
03-03-2008, 06:50 PM
Could a brake master cylinder be used as a pump for the water??

Just trying to think of things that build up pressure, like a grease gun.....

NOS_350X
03-03-2008, 08:05 PM
I think the master cyl is a decent idea, would just take a long while of pumping to build up enough pressure. Ive already thought of a grease gun. But inside your pipe your going to have a ton of grease and water in a nasty mess. And figured it woudnt be worth it.

SWIGIN
03-03-2008, 08:18 PM
well when water is in your brake lines it does compress....so use a master cly and cheap dot 3 fluid

im thinking like a truck MC not a atv MC

NOS_350X
03-03-2008, 09:33 PM
You can use water in a brake master. I have some from cars here. 3 gallons (thats a gess) of brake fluid aint going to be cheap.

rex found this for me, i would say that would be about perfect.
http://images.craigslist.org/0102060103060116132008021670e7fdc575ca9e2576002014 .jpg

http://orangecounty.craigslist.org/tls/576515844.html

Billy Golightly
03-03-2008, 09:36 PM
Thats exactly what I was just fixing to reply with and suggest, a what we call here "porta-power". The only thing is I'm not sure it'll be enough volume unless you do some sort of sub-tank.

Autophysn
03-03-2008, 09:45 PM
I would think that the water would have to be in the pipe at the time of heating it up. Then as the metal becomes maleable, you would add pressure.
Kinda like blow molding glass.

Autophysn
03-03-2008, 09:50 PM
I forgot, reason being, and I do not have much experience with this. But My dad is a old school body man, one of his techniques is heating the metal and splashing water to it, to make the metal conract immeadiatley. This way, I guess, he can remove the strech the metal aquired from the impact. What ever it may be. Again, I am a mechanic, I suck at body work. My 2 sense

hondahaulic
03-03-2008, 10:12 PM
yea my next suggestion was going to be a porta power. I was looking at ours and its got a 10 ton sticker on the hand pump that should be plenty.

Im not really sure that a tractor would put out too much pressure though, I mean with it at idle speed and the proper lever valve, you can operate hydraulics really slowly. What will extra pressure hurt? It would have to over inflate the pipe before it ruptured it no matter how much pressure there is.

cr480r
03-04-2008, 05:48 AM
I would use the powerwasher... And plumb in a guage and an adjustable pressure regulator if the existing one didn't have enough adjustment range... Hydrualics and brake fluid just sounds like a mess IMO... water is much easier to clean up, and free of cost... lol..

money89tractors
03-04-2008, 08:09 AM
That porta-power thing is what theyre using in one of the links posted. If it is filled with water, and you pre-fill the "exhaust", there shouldnt be any reason there wouldnt be enough fluid to expand the pipe.

I would, however, want an inline valve that i can close in case (for some odd chance) there isnt enough fluid in the porta-power to completely expand the pipe. This valve will allow you to take the pressure off the porta-power so you can refill it.

-Phil

NOS_350X
03-05-2008, 03:09 AM
auto, using heat while it is presurized with watter would be a worse idea than even presurizing it with air. Basicaly at that point you created a steem engine. Instant explosition as you get it hot enough to turn to steem.

Now im going back and fourth between several ideas, one is trying to find some sort or correct pump that can pump the watter how i want, but thats not getting ANYWHERE.
Another is a car/truck brake master, now i dono if yall have tryed this but you can run watter in a brake system. (seen a guy do it at a flattrack race) the master will pump water. Now im thinking it will just take FOREVER to build up the amount of pressure needed, In one of the links it was 25 bar, which i was told is around 375psi you will be doing alot of pumping.
That brings me back to the idea of the pressure washer, i would have a guage on one end with a valve (spicket or something simular) on the other end start off with just a watter hose giving the pressure to make shure you got it all sealed up. Then use the pressure washer (the end of mine has a quick cuppler) just pop it on and pull the trigger, biggest problem is going slowely, BUT if you have ever see how much volume comes out of one? Take off the nozzle and check it, Really its not that much. I think it would still go decently slow.
Well those are my thoughts, any other ideas are grately appericated.

cr480r
03-05-2008, 06:22 AM
pulling the trigger on a pressure washer doesnt regulate pressure... just flow... you would need an adjustable pressure regulator... maybe even two of them to get down to a safe pressure range...

SWIGIN
03-05-2008, 08:40 AM
auto, using heat while it is presurized with watter would be a worse idea than even presurizing it with air. Basicaly at that point you created a steem engine. Instant explosition as you get it hot enough to turn to steem.

Now im going back and fourth between several ideas, one is trying to find some sort or correct pump that can pump the watter how i want, but thats not getting ANYWHERE.
Another is a car/truck brake master, now i dono if yall have tryed this but you can run watter in a brake system. (seen a guy do it at a flattrack race) the master will pump water. Now im thinking it will just take FOREVER to build up the amount of pressure needed, In one of the links it was 25 bar, which i was told is around 375psi you will be doing alot of pumping.
That brings me back to the idea of the pressure washer, i would have a guage on one end with a valve (spicket or something simular) on the other end start off with just a watter hose giving the pressure to make shure you got it all sealed up. Then use the pressure washer (the end of mine has a quick cuppler) just pop it on and pull the trigger, biggest problem is going slowely, BUT if you have ever see how much volume comes out of one? Take off the nozzle and check it, Really its not that much. I think it would still go decently slow.
Well those are my thoughts, any other ideas are grately appericated.

375psi would not be alot of pumping with brake fluid since it dont compress like water....and they build a lot more presure then that in a panic stop

Billy Golightly
03-05-2008, 11:02 AM
Unless your gonna be using a huge mastercylinder, I think the small amount of volume its going to move will take forever to pump up a pipe. I mean look how small the resivoirs are, you'd need what, like a 100 or of those to fill a normal sized expansion chamber? Your looking at several gallons at least.

SWIGIN
03-05-2008, 03:38 PM
i thought we were talking ghetto..... the porta power is the way id go

but ether way will use the same amount of fluid and id still use hydro fluid of some kind

NOS_350X
03-05-2008, 05:28 PM
cr480 because its a liquid your pressure is going to be controled by your volume.


Spend a few minutes talking to a friend of mine that is a plumber. He has a hand water pump, Pumps up to 500psi. Then he said before they got that they used a pressure washer, it just took a bit longer to get there because they dont push much volume. SO i will be trying using a pressure washer. hydrulic fluid donset compress, neather does watter.

Here is another idea i had, On metal tanks on the bikes when they get a dent you fill with water and freze it, BAM no dent. Now could you do in several times freezing water in the pipe possibly? No that is just a brainstorming idea. I will be using a pressure washer.

money89tractors
03-05-2008, 06:59 PM
Here is another idea i had, On metal tanks on the bikes when they get a dent you fill with water and freze it, BAM no dent. Now could you do in several times freezing water in the pipe possibly? No that is just a brainstorming idea. I will be using a pressure washer.

Freezing water in it might work, but would be a VERY slow process.

Although there is a great deal of pressure here, the water being pushed in is whats forming the chamber. The pressure comes from pushing the water into the pipe. Once the water is in, there will be no more pressure. So pressure is only build when adding the water, its not constant.

-Phil

Daddio
03-23-2008, 02:12 PM
Here's a cool link. I will post more later.
http://www.gifford.ca/hydroform.html