As stated by widgeon, a similar topic was discussed in rec.aviation.rotocraft. The original post had nothing to do with diesel engines in Robbies, however the discussion turned in that direction. There was speculation about an R55 / R66 – turbine, turbo, diesel etc … all speculation !
One of the things that was uncovered was that there are a few companies developing diesel aviation engines. The first consensus was diesel’s will never hack it, they are too heavy ….. well if we examine the Zoche vs the Lycoming we get :
ZO 02A 530. .Height 25.5 24.5. .Width 25.5 33.3. .Length 32.9 37.2. .Weight 271 369. .HP 250 300
Zoche also claim sea level performance up to 9000 ft. Believable if you consider the major advancement in diesel technology in the past 2 years or so. Ever driven the latest BMW 530D. Before I get shot down, I know the BM doesn’t have a Zoche under the hood, however technology has advanced and performance / reliability has had a serious shot in the arm.
I’m a recreational pilot and only fly for the pleasure of it and all my flying is done above 6000ft, in fact I have only ever logged 1.5 hr at sea level. If there were two 44’s next to each other, one standard and the other diesel, it wouldn’t be a difficult choice for me to make to fly the diesel version. We always joke here, the 44 is a great 2 seater ! Considering we all trained in the 22 and still fly them all the time, maybe there should also be a diesel option for the 22 !