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jordey |
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jordey Nitrous Nuisance
Joined: 17 Sep 2012 Karma :
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Posted: 19:13 - 24 May 2013 Post subject: hydroforming an expansion chamber? tzr 125 |
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i have a tzr 125r 1993 project bike. the exhaust is scratched and dented and the mount isn't great on it, so was looking for a new exhaust. theres not many exhausts available for the bike, and if i wanted an aftermarket one i would have to buy new, which is expensive and they don't even look or sound good. i've seen videos of people hydroforming an expansion chamber and it doesn't look that difficult. this website also gives a fairly detailed how to:
https://www.eurospares.com/frame8.htm
i dont have alot of experience welding but have a mate who can help out if needs be. if anyones done this, how difficult was it to actually do it?
also, how would i know what size and shape to make the cutout?
and im assuming a different size/ shape expansion chamber would give a different sound and performance?
if i went down this route for an expansion chamber, what end can could i make fit? the original exhaust still works so im not in a mad rush to get a new one sorted quickly |
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Copycat73 |
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Copycat73 World Chat Champion
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jordey |
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jordey Nitrous Nuisance
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Zen Dog |
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Zen Dog World Chat Champion
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Posted: 21:19 - 24 May 2013 Post subject: |
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I think the problem is less the hydroforming (although that is a problem), and more the extensive mathmatics and in-depth knowledge involved in designing a 2-stroke pipe for a decent powercurve. Companies who make aftermarket pipes put in a lot of development time, and they don't always get it right.
You're also probably going to need dyno time to setup the bike properly for the pipe afterwards. Get this months Practical Sportsbike, they have an article about a guy trying to sort out a custom pipe for his RGV250 (with lots of professional help).
Zen Dog ____________________ Current - '94 VFR750FR, '00 VFR800FI Previous - '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win (chinese copy of an old Honda design with a C90 engine)
My bike trip around S.E. Asia 2010/2011 |
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jordey |
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jordey Nitrous Nuisance
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jordey |
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jordey Nitrous Nuisance
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bladerunner |
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bladerunner World Chat Champion
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bladerunner |
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bladerunner |
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Walloper |
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Walloper Super Spammer
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Posted: 09:56 - 25 May 2013 Post subject: |
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Hydroforming a one-off exhaust?
The equipment to complete the hydroforming will cost you as much or more than a custom pipe from a supplier/OEM.
As far as the technique is concerned, it is just a method of fabrication. It is rather specialised and requires a lot of experience to get the correct result.
Chopping out some plate from a 'known' template and welding it together will be much easier and probably 10% of the cost after tooling is factored into the plan.
Hydroforming is also fraut with dangerous high pressure risks:
Explosion like the same energy released by a lump of dynamite.
Hypodermic injection. Lethal/Life changing injury.
Lots of other evil stuff.
Walk away from this website https://www.eurospares.com/graphics/hydroform/hydroform001a.jpg
____________________ W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair |
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jordey |
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jordey Nitrous Nuisance
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Posted: 12:55 - 25 May 2013 Post subject: |
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Walloper wrote: | Hydroforming a one-off exhaust?
The equipment to complete the hydroforming will cost you as much or more than a custom pipe from a supplier/OEM.
As far as the technique is concerned, it is just a method of fabrication. It is rather specialised and requires a lot of experience to get the correct result.
Chopping out some plate from a 'known' template and welding it together will be much easier and probably 10% of the cost after tooling is factored into the plan.
Hydroforming is also fraut with dangerous high pressure risks:
Explosion like the same energy released by a lump of dynamite.
Hypodermic injection. Lethal/Life changing injury.
Lots of other evil stuff.
Walk away from this website https://www.eurospares.com/graphics/hydroform/hydroform001a.jpg
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i don't really need to spend much on equipment tbh. i've already got a welder so dont need to buy that. as for the pump i'm gonna look around to see if i can borrow one off of a mate or rent one, so shouldn't cost me nearly as much as a stock pipe.
as for fabrication i was planning on using a template, but they're a little difficult to find. i could base the dimensions off of the stock exhaust if needs be. or i could use that program to give me the shape/ dimensions.
that website also says there isn't really any risk of explosion as the water will only leak out if there is a hole, as there would be no air/ gas in chamber. theres notes on this at the bottom of the how to. |
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Walloper |
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Walloper Super Spammer
Joined: 24 Feb 2005 Karma :
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Posted: 13:30 - 25 May 2013 Post subject: |
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jordey wrote: | Walloper wrote: | Hydroforming a one-off exhaust?
The equipment to complete the hydroforming will cost you as much or more than a custom pipe from a supplier/OEM.
As far as the technique is concerned, it is just a method of fabrication. It is rather specialised and requires a lot of experience to get the correct result.
Chopping out some plate from a 'known' template and welding it together will be much easier and probably 10% of the cost after tooling is factored into the plan.
Hydroforming is also fraut with dangerous high pressure risks:
Explosion like the same energy released by a lump of dynamite.
Hypodermic injection. Lethal/Life changing injury.
Lots of other evil stuff.
Walk away from this website https://www.eurospares.com/graphics/hydroform/hydroform001a.jpg
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i don't really need to spend much on equipment tbh. i've already got a welder so dont need to buy that. as for the pump i'm gonna look around to see if i can borrow one off of a mate or rent one, so shouldn't cost me nearly as much as a stock pipe.
as for fabrication i was planning on using a template, but they're a little difficult to find. i could base the dimensions off of the stock exhaust if needs be. or i could use that program to give me the shape/ dimensions.
that website also says there isn't really any risk of explosion as the water will only leak out if there is a hole, as there would be no air/ gas in chamber. theres notes on this at the bottom of the how to. |
This technique relies on both sheets to be cut to a pre-determined profile and welded together at the edges.
Then the 'balloon' is inflated with water. And hydraulic force forms a pipe which will/conform to the tempate.
If you miss-cut then the shape will suffer. And you will need to select a suitable material. SS comes in several grades FYI.
If you can be arsed go for it. Your welding will have to be good. ____________________ W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair |
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jordey |
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jordey Nitrous Nuisance
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Drake |
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Drake World Chat Champion
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Posted: 15:42 - 25 May 2013 Post subject: |
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the fact your asking shows you wont make a usable exhaust, just buy one. ____________________ was: derbi senda, aprilia sx125, nsr250 mc16, cagiva mito, cb600 hornet now: mk1 bandit, KR1S, landrover series 3 light weight 2.5 petrol, 5speed box |
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Walloper |
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Walloper Super Spammer
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Posted: 16:34 - 25 May 2013 Post subject: |
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If you don't know already, the expansion part of a 2 stroke petrol engine exhaust does more than control sound/noise.
It is designed to, more importantly, act like an exhaust valve and block the fresh air-fuel mixture 'blowing' through the engine at the start of the compression stroke. It employs a bit of science and a lot of witchcraft. The speed of the gas flow, temperature of the gas and the pressure of the gas all contribute to the back-pressure needed to 'seal' the exhaust port. If you get the design wrong you can easily down-rate the engine performance. Which will lose you several man-points on here.
The idea looks simple but I'll wager 'a pound to a bucket of shite' there will be many 'prototypes' before the final product is born.
If yer keen to have a go then fcuk it. Knock yer sel out.
____________________ W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair |
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jordey |
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jordey Nitrous Nuisance
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jordey |
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jordey Nitrous Nuisance
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Zen Dog |
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Zen Dog World Chat Champion
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Posted: 18:25 - 25 May 2013 Post subject: |
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I don't know about tweaking for different sounds, 2 strokes always sound awesome to me! Lots of OEM pipes are dual-skinned to make them quieter though I think, and aftermarket ones only single-skinned. You should probably bear that in mind (that the internal and external profile will be different) if you use your original pipe as a template (which is probably your best option to end up with something useable).
Apparently the pipe length after the expansion chamber "largely determines the overall exhaust-system back pressure". More length, and more pressure is good for power, but also increases heat, which can be a problem. So to answer your question, shortening the pipe will give you less power.
EDIT - I'd get the used stock one, or look at repairing your existing one, if the ultimate aim is to ride the bike. On the other hand, if the ultimate aim is to set yourself an engineering project, go nuts, just bear in mind that its likely to cost a fair bit in time, effort and money to get something useable.
Zen Dog ____________________ Current - '94 VFR750FR, '00 VFR800FI Previous - '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win (chinese copy of an old Honda design with a C90 engine)
My bike trip around S.E. Asia 2010/2011 |
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Copycat73 |
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Copycat73 World Chat Champion
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Vincent |
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Vincent Banned
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jordey |
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jordey Nitrous Nuisance
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Posted: 20:08 - 25 May 2013 Post subject: |
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Zen Dog wrote: | I don't know about tweaking for different sounds, 2 strokes always sound awesome to me! Lots of OEM pipes are dual-skinned to make them quieter though I think, and aftermarket ones only single-skinned. You should probably bear that in mind (that the internal and external profile will be different) if you use your original pipe as a template (which is probably your best option to end up with something useable).
Apparently the pipe length after the expansion chamber "largely determines the overall exhaust-system back pressure". More length, and more pressure is good for power, but also increases heat, which can be a problem. So to answer your question, shortening the pipe will give you less power.
EDIT - I'd get the used stock one, or look at repairing your existing one, if the ultimate aim is to ride the bike. On the other hand, if the ultimate aim is to set yourself an engineering project, go nuts, just bear in mind that its likely to cost a fair bit in time, effort and money to get something useable.
Zen Dog |
yeah the only thing about 2 strokes i dont like is they're really high pitched, and makes it sound like a moped. if i could get a nicer exhaust note it would be nice but isn't that important
as for the profile, the end product will likely be slightly smaller than the stock exhaust as the stock will be a little more spherical so should have a slightly largely volume, so if i go by the external profile it should give a fairly close size internal profile to the original once expanded, if that makes sense. i could also make the template a couple mm's smaller all round to compensate.
yeah i read the pipe length affects power which is why i didnt do it. do you know how long i could make the pipe? as i originally wanted it to be closer to the body (like an r125), so could curve some pipe round to make it exit before the rear wheel, but not sure how long i could make the pipe if heat is an issue.
i will be using the stock one for the time being, its on the bike and works, but im looking for a nicer replacement, which isnt as simple as just buying one! |
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Pete. |
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Pete. Super Spammer
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Posted: 20:45 - 25 May 2013 Post subject: |
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Don't be told you can't do something, it'll fail, you'll blow your bike up, it's not worth it etc. That's what I was told when I announced I was going to build my own turbo setup and it just made me more determined.
You can make a hand-powered high-pressure water/oil pump with a few bits of metal and a long tube for a handle, if you've got a lathe.
I'd buy a cheapo bottle jack, remove the piston and weld a cap over the hole with a fitting for some hydraulic tube. A tube into the filler hole to a larger reservoir and you have your pump. Or get a portapower pump off eBay for £50.
Got a tig welder? Just buy a sheet of 20 gauge steel, a pair of tinsnips and have at it. Cut some test profiles to get your method working and you're set. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good |
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bladerunner |
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Vincent |
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Old Thread Alert!
The last post was made 11 years, 161 days ago. Instead of replying here, would creating a new thread be more useful? |
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