For a flash boiler, what is best for the tubing?

I‘m designing a steam engine, and naturally it needs a steam generator. I want to wrap a three layer coil of 1/4 copper tube and fire it probably with a gasoline torch (it‘s for a motorcycle). I want to know if there is a better way to do this, and, more importantly, what the best way to coil it without crimping it is. I want to use a form, and my best ideas are to use ice made from soapy water to fill the pipe, like they do with instruments like trombones. Or maybe heat it, which would mean that, unless I quench it (if I‘m right) it will be softer (annealed). That is the last part to my question. Is it better for the pipe to be soft or hard in case of failure? Or does it matter because the heat from the torch will anneal it anyway? (I don‘t think this is as likely) Please try to be thorough and respond to updates if there are any. Thanks very much for your time and consideration and the help that is a product of them!

In the age of modern efficient light internal combustion engines, Why Oh! Why.Do you want to experiment with external combustion heavy dangerous inefficient engines? Why not batteries? Why on all things a motorcycle? There are people that have placed steam engines on bicycles. It's a 'hobby'! Do a search: 'Steam Bicycle' There are other sources

you will be spending $150 on something that isn't going to have much advantage over what you have now, if it worked as good as some people say the factory would put them on as factory equiptment.

if you get a cold air intake it wil have a better sound

Yes High Performance is most of the time, better then stock.

In the age of modern efficient light internal combustion engines, Why Oh! Why.Do you want to experiment with external combustion heavy dangerous inefficient engines? Why not batteries? Why on all things a motorcycle? There are people that have placed steam engines on bicycles. It's a 'hobby'! Do a search: 'Steam Bicycle' There are other sources

Copper pipe with a cloth cord or rope inside it and wrap around a pipe of moderate size- rope fill keeps pipe from crimping. a outside of coil pipe for container flames, a small external water tank connected to bottom of copper coil with gravity feed , steam outlet at top of copper coil leading to the steam piston cylinder and then depends on whether you run expelled steam to a simple condenser /radiator that leads back to the water tank with a one way check valve in circuit. 20 pounds pressure can get you going, 50 pound pressure ok on lead soldered joints but getting to limit of compression fittings. If you do a total loss of steam after going through piston, will have short range per gallon. A 5hp Briggs engine with a 1:1 cam gear and check valve can act as a engine- drill a 3/8 hole at base of cylinder just above top ring position at BDC, tap hole for coarse thread fit pipe union+tube and run the tube to a condenser- a power steering single U cooler can be- or used to be - cheap salvage yard pull for recirculating steam. could also as noted to a loss of steam at bottom of stroke. High pressure inlet to intake port for simple one way, exhaust is another pipe to condenser or total loss option- and most Briggs small engine had exhaust port threaded for 1/2 to 3/4 BPT size so simple plumbing pipe threads in direct. Can make reversible engine by using a 2 way plumbing valve on inlet steam pipe and open/close fitting and T on both inlet and exhaust piping. Set steam pipe valve to the exhaust port, close the T fitting on exhaust piping and open the one T on the inlet port for exhaust to open air or condenser. Have fun and use safety release valves for over pressure.

you will be spending $150 on something that isn't going to have much advantage over what you have now, if it worked as good as some people say the factory would put them on as factory equiptment.

if you get a cold air intake it wil have a better sound

Yes High Performance is most of the time, better then stock.

Copper pipe with a cloth cord or rope inside it and wrap around a pipe of moderate size- rope fill keeps pipe from crimping. a outside of coil pipe for container flames, a small external water tank connected to bottom of copper coil with gravity feed , steam outlet at top of copper coil leading to the steam piston cylinder and then depends on whether you run expelled steam to a simple condenser /radiator that leads back to the water tank with a one way check valve in circuit. 20 pounds pressure can get you going, 50 pound pressure ok on lead soldered joints but getting to limit of compression fittings. If you do a total loss of steam after going through piston, will have short range per gallon. A 5hp Briggs engine with a 1:1 cam gear and check valve can act as a engine- drill a 3/8 hole at base of cylinder just above top ring position at BDC, tap hole for coarse thread fit pipe union+tube and run the tube to a condenser- a power steering single U cooler can be- or used to be - cheap salvage yard pull for recirculating steam. could also as noted to a loss of steam at bottom of stroke. High pressure inlet to intake port for simple one way, exhaust is another pipe to condenser or total loss option- and most Briggs small engine had exhaust port threaded for 1/2 to 3/4 BPT size so simple plumbing pipe threads in direct. Can make reversible engine by using a 2 way plumbing valve on inlet steam pipe and open/close fitting and T on both inlet and exhaust piping. Set steam pipe valve to the exhaust port, close the T fitting on exhaust piping and open the one T on the inlet port for exhaust to open air or condenser. Have fun and use safety release valves for over pressure.