<<I found this Centurion 4.0 eight cylinder jet fuel diesel engine
(certified
in Europe 10/28/04), 310 hp and about the same weight as the TSIO-550
www.centurion-engines.com/c40/c40_data.htm

I am not an aerodynamically guy and I am not able to calculate performance,
is there somebody out there able to help me see what performance an IV-P
will have with this engine?>>

I have a suspicion that the horsepower available might be comparable as
there is no real reason the diesel couldn't be operated continuously at a
higher percent of rated power than the standard gasoline engine.  However,
the full-power climb performance might be lower - except that with the gear
reduction the propeller is likely turning slower, allowing for a larger
diameter.  The problem I see is weight, as they claim an as-installed weight
of 625 pounds, which I think is maybe 75 pounds heavier than a TSIO550.  I
doubt if they include the coolant or heat exchanger.  I've done lots of
design work on liquid-cooled installations and one of the more pesky
problems is cooling air flow.  Typical air-cooled  designs assume a cooling
air temperature rise of up to 150F, about double what you might allow for a
liquid cooling system.  Therefore, the liquid cooling system requires about
twice the cooling air flow of an air-cooled engine.  If you're really good
you can make up for that with a more efficient cooling air flow path, but
that takes space.

Gary Casey