This is what conti wants to release in 2016. It's 130lbs heavier than the IO-550 dry with the same HP and runs on jetA.
http://www.aopa.org/News-and-Video/All-News/2014/July/30/Continental-310-hp-diesel-makes-first-flight?WT.mc_id=140801epilot&WT.mc_sect=osh