Type Half Crankshaft

Rev - Nov 13, 2017

By Jan Zumwalt (EAA #66327)

See Also

For additional information on this topic see VW Type 1 & 2 Crankshaft.

Which Crankshaft

94 by 86mm is the 45hp version. I am running 94 by 82 and the crank hits the camshaft so I have to do some additional clearance to the normal case. The thing about Chevy journals is they are smaller so you have less metal to remove for the stroker crank to clear. Note that most the 45hp engines that are currently running on aircraft have special Nikasil cylinders to provide adequate cooling. The special cylinders are all aluminium while the standard cylinders are cast iron. I am estimating 40hp for my engine and believe it can be cooled adequately with some sheet metal forcing prop wash around the back of the cast iron cylinders.

While 45hp is nice, it does cost quite a bit for the Nikasil cylinders. The more affordable half VW is the 92 by 78mm which is 37hp. In any case, you will have to buy a stroker crank and cut it. The crank, rods, and piston assembly must be balanced to avoid excessive vibration.