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"Anyone see any major disadvantage of diesel?"
Well, yes. Jet A is not available at a lot of smaller airports, where as almost all airports have 100LL. It would be a major nightmare to divert, land without much gas and find that there is no Jet A for 100 miles around you.
The centurion engine weighs 295lb and makes only 135 HP. It's turbo charged with makes the weight a little more acceptable, but the engine also requires an MT 3 bladed constant speed propeller. The MT constant speed prop is expensive, has a troubled past (throwing blades), and the centurion engine requires it.
Power to Weight - 295 lbs/ 135 HP = 2.18 !!!! (and we havn't even put the C/S prop on yet! add at least 40lbs for C/S prop over a fixed pitch prop)
The claim a specific fuel consumption of 0.336 lbs/HP-hr at "best economy", 0.35 - 0.37 are propbably real world numbers which is still better than you will get with any 4 stroke engine.
The centurion engine costs $19,500 plus shipping from Europe. That's about the price of a new XP-360 with electronic ignition. The centurion engine also requires an $8-10,000 propeller to get reasonable performance. The XP-360 will perform well with a $1500 fixed propeller because of the extra HP.
Having said all that I think the centurion engine may be a good choice for European operators. Avgas is heavily taxed in Europe while jet fuel is not. Avgas is 3 or 4 times more expensive than jet in Europe. The Centurion engine makes no sense in the US as Avgas and jet are about the same price in small quantities here.
The same idea goes for the sma engine. It's very heavy. It's only 305 cubic inches and they are claiming 230HP at 2200 rpm, un-turbocharged. I don't buy it. They don't talk about price and it didn't look like they have actually sold one to the public yet.
Also two things -
Deisel fuel has more BTUs/gallon than avgas, but diesel is heavier. Make sure you look at fuel burn in lbs/hr not gallons/hr.
Horsepower is what matters, not torque. HP = Torque * RPM
Scott
