In common with the Jumo 213 series of engines, the Jumo 222 had 3 valves per cylinder - 2 inlet and 1 exhaust.
The exhaust had an overall valve seat diameter of 63.5mm, stem diameter of 14.7mm and an overall length of 131mm.
The inlets had overall valve seat diameter of 55.2mm, stem diameter of 11.97mm and overall length of 119.5mm
The valves were seated in a vee shaped combustion chamber. The direct fuel injector sat between the two inlet valves. Dual spark plugs were mounted fore and aft at the apex of the combustion chamber.
The valves are actuated by a single overhead camshaft, rockers with roller followers and adjustable tappets. The camshaft is driven by a drive train at the rear of the engine.
Magnetos and other auxiliary drives are operated at the rear of the engine, in the intermediate gear wheel casing. Block #1 carries the hydraulic pump, magnetos are mounted to Blocks #2 and #3, the fuel pump is on Block #4, the secondary coolant pump is on Block #5 and a 3kW generator is on Block #6, if required.
The rear casing has the air trunks from the supercharger, the 2 speed supercharger drive, the oil pumps and deaerator housing.
The supercharger followed Jumo 213 practice in that it was a double shrouded impeller with radially mounted preswirl throttle vanes adjacent to rotating entry guide vanes.
The diffuser blades are cast on a ring which can be separated from the main supercharger housing casting.
An estimate of the supercharger performance gave the following possible boost pressures with wide open throttle and 2,700rpm (cruising rpm):
Code:
Height (ft) 0 5,000 10,000 15,000 20,000 25,000
MS Boost (psi) 13.7 9.8 6.0 2.4 -0.4 -
FS Boost (psi) - 22.3 17.3 12.5 8.1 3.9
The diffuser had not been machined, so it was suspected that it was not yet complete and had been fitted for matching tests before final machining.
The Jumo 22 was fitted with a Master Control Box (Kommandogerät), which was similar to the one found on the Jumo 213.
The control box is mounted to the upper part of the supercharger entry casing.It controls boost pressure, mixture strength, ignition advance, and propeller speed.
Three fuel injection pumps are mounted between banks 2 and 3, 4 and 5, 6 and 1.
Each of the two magnetos and distributors supply electricity to 3 banks. As such there is no redundancy or dual ignition system as usually found on aero engines of the era.
The oil system used a number of pumps - main scavenge pump, main pressure pump, secondary system oil pump, front scavenge pump (returns oil from the reduction case sump), three auxiliary scavenge pumps (driven off the end of the camshafts of banks #4, 5 and 6). Oil from banks #1 and #4 is drained by external lines to the pumps on banks #5 and #6. The pump on #4 bank scavenges from teh crankcase breather, which was missing on the engine examined.
When running with MW50 injection the Jumo 222 could devlop 2,130hp in MS gear and 2,250hp in FS gear at sea level.
From capture German documents the British determined that:
Code:
Jumo 222A/B-1
Bore: 135mm 5.31"
Stroke: 135mm 5.31"
Capacity: 43.3l 2642ci
Max RPM: 3200
Jumo 222A/B-2
Bore: 140mm 5.51"
Stroke: 135mm 5.31"
Capacity: 49.9l 3045ci
Max RPM: 2900
Jumo 222A/B-3 - same as A/B-2 but with new supercharger with heigher rated altitude
Jumo 222C/D
Bore: 145mm 5.71"
Stroke: 140mm 5.51"
Capacity: 55.4l 3838ci
Max RPM: 3200
Jumo 222E/F
Bore: 140mm 5.51"
Stroke: 135mm 5.31"
Capacity: 49.9l 3045ci
Max RPM: 3000
The E/F was the same as A/B-2 but with two stage supercharger. The first stage driven by mechanical gears, the second stage by variable speed drive. There was also a charge cooler fitted with this engine. Maximum boost altitude 11km, though tests had only confirmed 9km.
A turbo version of the Jumo was also tested, based on either the A/B-1, A/B-2 or A/B-3. The turbocharger was a Borsig model.
A 36 cylinder version of the 222 was conceived, but cancelled before completion.
Code:
Jumo 225
Bore: 135mm 5.31"
Stroke: 135mm 5.31"
Capacity: 69.5l 2642ci
Max RPM: 3200
T/O Power: 3500hp
The performance of the various models was given as:
Code:
222 A/B-1 222 A/B-2 222 A/B-3 222 C/D 222 E/F 222 Turbo
Take-off/emergency 2500hp 2500hp 2500hp 3000hp 2500hp 1920hp 2400hp 2070hp
At Altitude 0km 0km 0km 0km 0km 9km 0km 12.3km
Engine Speed 3200rpm 2900rpm 3000rpm 3200rpm 3000rpm 3000rpm 3200rpm 3200rpm
Climb and Combat 2200hp 2250hp 2020hp 2230hp 1920hp 2600hp 1780hp 2170hp 1900hp
At Altitude 0km 0km 5km 0km 6km 0km 0km 0km 12.4km
Engine Speed 2900rpm 2700rpm 2700rpm 2700rpm 2700rpm 2900rpm 2900rpm 2900rpm 2900rpm