Lifer

My Feedback: (1)

I recently sent this to a vendor, but thought I'd post it on RCU as well. The note should speak for itself:

"As the 15cc has a bolt-on cylinder, I would like to explore a possibility. Most aircraft
have right thrust which means the engine is canted to the left (when viewed from above
and behind). This means that for an inverted installation there is very little space for
the muffler. What I want to determine is the possibility of rotating the cylinder 180
degrees so that the muffler is on the opposite side.
Could this be done by rotating the cylinder and leaving the piston as is (which would
need the issue of the ring gap still oriented away from port openings, OR pulling the
back of the engine off and rotating the ENTIRE assembly and re-installing the connecting
rod from the opposite direction.

I have done this on MVVS and K&B engines, but these are not gas with rear-intakes.

The net result for my installation would be a LOT more room for the muffler and not
needing to buy a Pitts-style muffler.

Finally, if it is possible, what charge would you make for doing this rotation? I could
do it myself but it would void the warranty.

Thank you for your time and I do hope you can check this out for me."



I am referencing this primarily for cowled installations.

earlwb

Normally it isn't a problem to rotate the cylinder 90 or 180 degrees or even 270 in some cases, like for a boat.
But you need to check the wrist pin on the piston to ensure it won't catch in a port. Some engines use a nylon button and no retaining rings, so it might be a problem if the wrist pin and a nylon button happen to align with a port then.
Then you need to check to see if the port cutouts in the crankcase bottom need to be cut to match the ports or not in the cylinder. Some engines just have the ports cut to clear it only for its normal cylinder orientation. Also you need to make sure you have some room left for it, as sometimes they made the crankcase for mounting the cylinder on one way only and there isn't any extra metal in the crankcase to allow you to make the cutouts if you rotate the cylinder.
There also might be a issue with the spark plug sometimes. It depends on the angle or position of the spark plug in the cylinder head, but sometimes it winds up being a problem in some cases.
But other than that it should not be a problem.

zs6gnp

At the bottom of this link:  http://www.rcuniverse.com/forum/m_94...tm.htm#9481727

AJsToyz

Some of the pistons do have port reliefs cut into the piston skirt so turning 90 degrees would not be an option. Usually it's easier, if every thing lines up, to rotate 180.

Lifer

My Feedback: (1)

180 degrees would be my preference. I want the muffler on the other side when inverted.

AJsToyz

Take the cylinder off, do a 180 with the gasket and see if it all lines up. If it does you should be able to do it by also doing a 180 with the piston. Just don't force it back together, should be good to go. I would check the power out put also before the tear down, make sure there no major power loss.

Lifer

My Feedback: (1)

I'm comfortable doing the work, but need to find a retailer that would do it for a nominal fee so that the warranty would remain intact.

It will be going into a 60-size SNJ sometime in the future.

Thanks to all for their assistance!