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Octopus Trainer 10-26-2010 02:24 AM

Converting a VW classic Beetle's engine to run on steam
Currently I am building a fire tube high pressure boiler that is fueled by biomass and utilizes a wood gasifier fire box design. Want a steam engine to run off of the boiler. The end goal is to be able to build a automobile that runs off of biomass.
I was planning on converting a VW classic Beetle's engine into steam because their engines are fairly cheap, easy to modify, simple, and air cooled. Air cooled engines i believe are the easiest to convert into steam.

How would I go about converting a VW Beetle's Engine into a steam engine? All ideas and suggestions are greatly appreciated.

dcb 10-26-2010 04:31 AM

well, it doesn't need a compression stroke, so you might want a cam with twice as many lobes and no overlap.

Also you need to plumb hot high pressure high volume steam to the intake ports, the same sorts of heat and pressure are needed as during regular combustion to make a similar amount of power.

Need some sort of throttle to control the steam being sent to the motor.

it might need more lube, maybe the oil control rings can be augmented, dunno.

I'm sure it's been done though,

gasstingy 10-26-2010 08:40 AM

I saw on Planet Green where a wood gasifier was used to run a small 4 cycle engine. The "gas" was ported directly into the intake stream and the engine ran good. Of course, everything works great on TV. :D

bennelson 10-26-2010 04:02 PM

The big issue with steam: SAFETY!

In the U.S. in the mid 1800's, most shipwrecks causing many lost lives were steam-powered paddle-wheelers on the Mississippi river that exploded because of pressure problems in the steam engines.

Made sure to have a really good system for PRESSURE RELIEF!

Every home water heater has a temperature and pressure relief valve built right into it.

There were plenty of steam cars in the early 1900s. It would be interesting so see what they used for pressure control at that time.

Anyways, a steam car sounds like lots of fun, but please do keep safety in mind! :thumbup:

sawickm 10-26-2010 08:01 PM


Originally Posted by bennelson (Post 200901)
The big issue with steam: SAFETY! There were plenty of steam cars in the early 1900s. It would be interesting so see what they used for pressure control at that time.

Ben, Google “flash boiler” ;)

A Monotube or flash boiler is the most efficient, lightest, and safest boiler. It is easy and inexpensive to construct. It produces steam as it is needed, it does not store the steam. Most old steam cars used a “Doble flash boiler”.

Check-out this modern steam engine that also uses a built-in flash boiler: Cyclone Power Technologies - How It Works


bennelson 10-27-2010 12:01 AM

Flash boilers are pretty cool. The engine in that link looks really interesting.

From Octopus Trainers first post, it sounds like he is considering converting a internal combustion engine to a steam engine.

There are safe ways to deal with steam systems. I just wanted to throw the big warning out there because steam is one of those things that is FAR MORE powerful than people give it credit for - especially if somebody is doing any sort of home-brew system! :rolleyes:

SoobieOut 10-27-2010 12:26 AM

That link for the Cyclone steam engine is way cool. I can see many advantages. I like the radial engine design and closed loop steam system.

basjoos 10-27-2010 06:33 AM

One of the main problems in converting an internal combustion engine to steam is the totally opposite approaches that steam and IC engines take toward heat loss from the cylinders. In a IC engine combustion is taking place in the cylinders, so they are designed to extract heat from the cylinder walls to keep the cylinders from overheating. But with a steam engine, combustion takes place away from the cylinders and, since any heat loss from the cylinder wall reduces engine efficiency, they are designed to minimize heat loss from the cylinder walls. So as as a minimum, you are going to need to get rid of the air cooled engine's cooling fins and insulate the cylinders to hold in the steam's heat as it enters and is expanded in the cylinders.

Its hard to build a very efficient steam engine from an IC engine because of this excessive heat loss and the single cylinder size makes it difficult to impliment the multiple (douple, triple, or quadruple) expansion cylinder sequence that is needed to produce an efficient steam engine. Each subsequent expansion step needs a piston of larger surface area to utilize the lowered steam pressure of each steam expansion.

Automcdonough 10-28-2010 08:45 PM

Not if you have some EV components to cool off, or want some AC.. I doubt it would get that cold though, it's steam, not straight compressed air. Wouldn't you want to ensure that the steam is converted back to water for the exhaust stroke? or is this going to be open loop? Closed loop could be better, maintaining a static pressure in the system would help combustion efficiency. Or help it combust efficiently? lol

Either way you might want to consider running water+antifreeze in the crank instead of oil, because water WILL make it past the piston rings. Better to make a system of it than draining out a milkshake every 3k miles. Too bad the motor isn't made of stainless.

Boreas 10-28-2010 09:36 PM

I don't remember if old VWs use a chain or a gear to drive the camshaft. If it's a chain you may be able to use the original cam by using a smaller sprocket on the cam to match it's speed with the crankshaft and open the valves twice as often. I would consider a different way to supply oil pressure to the engine. The crank driven oil pump won't supply much pressure at low engine speeds when the engine starts to turn. The intake valve is designed to hold pressure on the cylinder not keep steam out. It might be ok if the valve spring pressure is greater than the steam pressure.

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