# Decked a VW case



## n3480h (Mar 10, 2014)

Building a VW aeroconversion engine for my experimental aircraft.  Today I decked the engine so that all four cylinders rest the same distance from the crankshaft centerline.  Sort of a "measure 27 times, cut once" deal, because a new case runs $1,000.  I made the flycutter and tipped it with a high speed steel cutter, then fixtured each case half on the minimill bed and indicated it into position.  The case material is a magnesium alloy.  It cut a lot like 7075.  The flycutter was best at low speed and feed.  Happy with the end result - all four planes are within .001" of the crankshaft centerline, and parallel to the centerline.  Ok, I got lucky.)

Thanks to Tony Wells for the encouragement.

Tom


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## vapremac (Mar 10, 2014)

Tom ,

 Fine job on everything you did there !  Experimental aircraft ? Like to see that when its
done.
 Did you figure the new compression ratio's once you were finished ?

William


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## n3480h (Mar 10, 2014)

Thank you for your kind words, William. Compression ratio on these opposed cylinder engines is set by total combustion chamber volume, and by spacer rings between the bottom of the cylinder and the case.  My interest in decking the case was only to make certain all four decks are equidistant from the crankshaft centerline.  With this done, I can now CC the heads to match volumes to within .1 CC, and then set proper valve train geometry. The result is improved power (because cylinders are not "fighting" each other on power stroke), much smoother running, better economy, and much better reliability.

The engine will go into my Sonerai IILS, a 150mph two seater, capable of moderate aerobatics.  I am building from plans, and raw materials.

Tom


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## GK1918 (Mar 10, 2014)

I trust that you follow the "flatnuzt" vidio  channel  ;  that is what they do...


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## n3480h (Mar 10, 2014)

Yes, I've seen his videos.  Wish I had the CNC for this kind of thing, but I get by.  My mentor is a guy in Quebec, with thousands of hours of experience with VW's, including the very successful one in his plane.

Tom


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## vapremac (Mar 10, 2014)

Tom ,

I am truly impressed by what you are doing , countless hours of planning and research must
have gone in to this.

William


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## n3480h (Mar 10, 2014)

Thank you again, William.  I am a private pilot, but hate renting planes, and can't afford the cost of a reliable used plane, so I build my own. This is my second - the first was a high performance biplane.  
It is the learning I love.  How to correctly weld with oxy-acetylene so I could weld the 4130 tube fuselage.  Then it was fabric work to cover the fuselage. Then composite layups for the canopy skirt.  Then painting. Then the engine, which requires machine work. Wings are aluminum, so I will learn more about riveting, including AN solid rivets.  Those of us who build think of these things as a series of manageable projects that one day are assembled into something fun to look at and fun to use.  It's the same as the guy who restores a car (or a machine tool), builds a dragster, or builds his own house. If we made a list of all that has to be done, we'd never take on such a huge thing. But, assembly by assembly . . . its manageable.

There is great joy in knowing that this aircraft is much stronger than a production aircraft, is far more efficient, and that I can fly it anywhere I'd care to go.  The first long flight will be to Custer State Park in SD.  From there, I can walk to trout water, catch my supper, and sleep under the wing.  Then its on to the next project.

Tom

My first build   v


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## xalky (Mar 10, 2014)

Awesome! :man:


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