Have a look at this   http://www.red-aircraft.com/projects/flight-tests/   And these specs:   http://www.red-aircraft.com/engines/red-a03-v12/  Best efficiency is about 0.344 lbs/hp hour at 400 hp.   A quick set of calculations show that 400 HP would burn about  21 gph of jet fuel and yield about 322 knots compared to TSIO 550 at 75% that started at 280 knots.    Ready to flip out your checkbook??   Fred         -------Original Message-------     With this kind of engine in the pipeline, http://www.aopa.org/oshkosh/2012/news/120723cessna-unveils-turbodiesel-182.html 240HP turbines sucking 28-32 gph are going to have a marketing problem.   Wolfgang