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Now I'll bet you haven't seen one of these before. I'm reliably informed that it's called a Rustler Merco Metamorph .60 (well, as reliably as can be when Charle Stone takes pen to paper, but then it's no April so we are probably safe ).
The engine was intended for F2B (control line stunt) competition use, or at least it was until Charlie pulled it apart for us to show the rather different exhaust arrangement. The engine has an AAC piston and liner setup with integral fins on the liner, exhausting at 45 degrees to the rear. It uses a clever manifold and convertible muffler arrangement that means it can be flown as either side or rear exhaust, depending on how you assemble the bits. Charlie reports that the engine was sourced from Ian Russell in England, but he does not know where they are manufactured. He also says that this one starts and runs well on FAI fuel (no nitro) and sounds very potent.
In case you are scratching your head over how the engine goes together, try this:
There are 8 holes in the liner. Taking the shaft end as "north", there are 4 "large" holes in the NE,NW,SE,SW corners of the liner as it were.
These allow the heads of the cylinder bolts to recess down to the lowest fin for excellent low-mass, hi-torque attachment.
This places the other 4 small tapped holes at N,S,W,E position which provides the required 45 degree alignment for the baffle slot in the head.
The cut-out in the piston skirt will face forward to clear the crank web, placing the baffle closer to the transfer passage (ie, it's facing backwards in the photo).