Back in the 70s, I had a lot of Elms to come down, some were about 4 feet diameter. Anything that was splitable with an axe while still sappy, was fairly easy, when I was 40 years younger, but the trunks got left a few years. I got a Hycrack to go on a MF35. I cut the trunks in rings about 6-8 inches long/thick. I would say that if you can lift it, then the Hycrack will split it. You can guess what the grain was like within Elm.
The Hycrack splits from the side, not with the grain. You don't have to try to go through the full width at first, you can nibble away around the edge. DON'T TRY SPLITTING WITH THE GRAIN.
For logs 6-8 long that just need to be split in half to go on the fire, the Hycrack will split them as fast as you can put them on the table. Just touch the point and by the time you have turned to pick up the next log, the first one is in two pieces.