Piston Ring Compressor

I made this as an inexpensive alternative to a metal tapered piston ring compressor. It worked well on the 87mm bore Nissan SR20DE I am building. I also made one in 86mm, since that is the stock bore for the SR20 and a number of other engines use that bore.

UPDATE: based on a suggestion, I've added a 100mm version with no letter, which can be scaled easily for any piston diameter.

Print Settings

I printed the compressor upside down at .2 mm layer height until the last 2 cm, dropping it down to .07 mm for the bottom of the compression. 

Post Processing

I used a little 400 grit sandpaper to break the bottom edge. Don't sand too much, or it will open up the diameter too much and the rings might get caught on top of the block. Use a little bit of engine oil when installing the pistons.