Wally Mounster 2x2x2 Engine

Letter and Diagram and Heads (Castings For Sale)


2x2x2 Engine

Wally Mounster Steam Engine 2x2x2   This engine is calculated to develop 25 hp at 1500 rpm.  Because it uses poppet valves it has potential to be an efficient and practical steam engine.  Wally lives in Tasmania and had made two earlier poppet valve engines for his steamboats.  He started working on this engine in 1987 and completed it in 1994 and has used it ever since in his small boat. 
A set of 45 pages of blueprints are available for purchase through the steam club. Castings for the four heads needed per engine are available from Tom Kimmel.  Wally sent him the pattern and that is how the castings are available.
At first blush this engine appears to be excessively busy.  After a while a person understands that it was a one-off design that had only one pattern for the four identical heads; the rest of the engine being weldements. The reason for the knife and fork push rods for the poppet valve train is because the three-dimensional sliding cam is on the crankshaft, thus no chain driven jack shaft is needed to power a camshaft.   Wally Mounster Steam Engine 2x2x2
Wally Mounster Steam Engine 2x2x2   A person could clean this engine up with some castings for the cross heads and cylinders or the heads and valves could be used with another crankshaft of a longer throw.  A person could even make this into a V-4 or in-line 4 if a larger engine is desired.  The genius of this engine is in the poppet valve seats and guides.  Those things are difficult to design without a lot of experience.

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Wally Mounster Engine Details   Wally Mounster Steam Engine 2x2x2
Wally Mounster Engine Details   Wally Mounster Engine Details

(Note: Click on a picture for a larger view, then enlarge it through your browser.)

Wally Mounster Steam Engine   Wally Mounster Steam Engine

Photography by Derek Peters

Wally Mounster Steam Engine    

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Letter and Diagram

Letter from Wally Mounster

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Mounster Heads For Sale

Wally Mounster Castings for Sale   Wally donated his detailed blueprints for this engine to the Steam Automobile Club of America where they can be purchased.  The engine is one big weldment except for the heads, which are cast.  Wally then sent me the pattern for the head and I had 20 of them cast of grey iron. These heads are for sale at $25 each which is cost.    Here is what Wally says in his ad for this engine.  The original one is for sale and it came from his steamboat ‘Otasell’.

“Otasell’s engine.  Double simple “V”; 1.89” bore x 2.5” stroke; poppet valves operated by sliding cam.  Balanced to run at 1000 rpm with 1000 psig superheated steam; normally run at about 500 rpm and 500 psig; estimated at 10 hp.  Variable stroke feed pump, steam operated cylinder drains; four ram cylinder oil pump”.  Wally is over in Tasmania.

    Wally Mounster Castings for Sale

If you wish to buy one or both of these heads please contact Tom.

As you can see this was a one off engine and thus designed to use the least amount of castings and the most amount of fabrication by welding.  If a person wanted to they could make castings for the cylinders and cross heads and change the looks of the engine.

The valve gear is quite involved and the reason is because of a design decision that Wally made.  He did not want a chain driven cam shaft, preferring the three dimensional cam camshaft to be part of the engine crankshaft.  The complex looking knife and fork valve gear is because of the double acting poppet valves and the location of the camshaft.  As they say all engineering is a series of compromises.  There is a lever that slides the cam going from full to short cutoff frontwards and backwards.  There is point contact so maybe a stepped cam would be a better long term design decision. 

The real beauty of this engine is that it is one of the very few designed to use poppet valves.  Once the head is machined it would be possible to use the head to make an engine with a longer stroke or to make it uniflow or to make a multi-cylinder engine in any other configuration.  Wally has done the hard part of steam engine design; figured out how to locate the poppet valves and steam passageways.  This should be quite an efficient engine.

From anything I know the only other Wally designed engine in existence was made a few years ago by the late Pete Barrett out of So. Cal and I purchased it from his estate and it is on display in my shop. 


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