But the internal workings were designed to operate more like a V engine with each adjacent pair of cylinder banks, each with a crossflow head, and it was liquid-cooled like most inlines.

Looking at a complete Jumo 222 from a "nose-on" view, the half-dozen cylinder banks were arranged at 60° equal angles from each other, such that neighbouring banks had their exhaust ports (at the "60°, 180° & 300°" spaces) and intake ports (at the "0°, 120° & 240°" spaces) facing each other, resulting in simpler "plumbing" from the rear-mounted supercharger and resulting in only three sets of exhaust headers.

Such comparatively low compression ratios were the best possible ones given the low-octane fuels available in Germany, but by increasing the speed of the engine to 3,200 rpm, the 222 delivered 1,850 kW (2,480 hp) at takeoff.

The only disappointing feature was the simple, single-stage two-speed supercharger, but even with this limitation, the engine still generated 1,641 kW (2,201 hp) at 5,000 m (16,000 ft).

Their troubled use and deficient installation design in the He 177A, Germany's only heavy bomber aircraft to see production and front-line service, prompted Reichsmarschall Hermann Göring to derisively label them in the late summer of 1942 as "welded-together engines".

[3] Conversely, the RLM was excited by the possibilities of the much more compact Jumo 222's design features, and the X engine configuration, 24 cylinder DB 604, of similar weight and displacement to the 222A but with somewhat lower specific power output.

One A-3 and B-3 powerplant each were allegedly fitted to the ninth Junkers Ju 288 prototype airframe Archived 2014-04-13 at the Wayback Machine for flight tests.

With a new bore and stroke of 145 mm × 140 mm (5.7 in × 5.5 in), the engine displacement increased a second time, to 55.5 L (3,386.8 in³), just very slightly larger than the contemporary Wright Duplex Cyclone American 18-cylinder air-cooled radial engine, which at the time was having its own significant problems ironed out, partially from the use of combustible magnesium-alloy metal for its crankcase.

Using the original 46.4 litre displacement A/B design, they added a new two-stage supercharger including a trio of aftercoolers, one per pair of neighboring cylinder banks for high-altitude use, producing the 222E and F-series.

By this point it appeared that the problems were finally being worked out, but bombing of the Junkers Motorenwerke's headquarters factories in Dessau made production almost impossible.

It also served to seriously hamper Luftwaffe piston-engined designs from 1940 to 1942, while many personnel within the Luftwaffe's government-operated technology development offices (like Oberst Edgar Petersen's chain of several Erprobungsstelle installations) and German military aviation corporate engineering departments waited for the Jumo 222 to finally start working.

In the end there was nothing to show for it, and late in the war the Luftwaffe was flying barely updated versions of their original pre-war designs.