Charles, the He-162 with V-tail is the subtype He-162 A-6, not He-162 Z.
The A-8 subtype with Jumo-004 D engines would weight up to 3000 Kg fully equipped. The plus in poweroutput was thought to increase the top speed to 918 Km/h or 570 mp/h. The thrust to weight ratio would be decreased to 0.31 instead of 0.32-0.33 in case of BMW-003 E (overrewed), but the plane would be able to sustain it´s top speed for a much longer time. But this is still better than anything except for the Me-163 and Meteor MK IV.
To the turbines:
The alloys used were tinadur (15% chromium, 15% nickel, 5% titanium and steel) for Jumo-004 B1 and cromadur (without nickel but therefore traces of manganese) for Jumo-004 B4/D/E. The first was thought to be more heat resistant but worser to produce, so it was replaced by cromadur, which could be easily welded instead of deeply drwan for the hollow turbine blades. In the end the later was easier to cool and therefore much more heat resistant than tinadur.
The disadvantage of the Jumo´s in general, beside of the average lifetime was its prone to flameouts under 6.000 rpm. This is mostly because of the fuel regulation system at lower rpm (easy to burn out the turbine blades if too much fuel is injected at low rpm):
A gear driven pump that produced a linear amount of fuel proportion to the engines rpm, the pilots throttle was directly connected to a bypass valve that would recirculate unwanted fuel. Fuel then passed to a centrifugal speed governer that operated another bypass valve. However, if the engines rpm was under 6.000 rpm (set to idle), the speed governer did not take into effect and the throttle bypass was the only fuel flow regulation. The pilots throttle also was connected to a governor by a pressure spring and would regulate the governers rpm setpoint this way. At full throttle, for example, the rpm of a Jumo-004 B4 was at 8875 rpm. Under 6.000 rpm the pilot had to be very careful, because without the governeor it was easy to allow to much fuel entering the combustion chambers and thereby burn them out.
So there can be a dissimilarity between engines rpm and air flow. The BMW-003 had a similar layout but in addition a device that consisted of an aneorid capsule across the compressor stages. This "accelerator valve" regulated the fuel flow in correspondence to the air flow (by pressure) and the governeor had less importance. In the end the actual air flow and spool up time was taken into account, so that the BMW-003 throttle could be handled less gingerly. The Jumo-004 on the other hand had a more sophisticated system to regulate the exhaust nozzle, while the BMW-003 exhaust nozzle was manually controlled.
Further improvements have been under work (some ceramics and thermocuple to reduce fuel flow if temp limits are to be exceeded).
That´s why type testings means something close to zero, the most limiting factor of the lifetime of early jets have been careful handling in the start and spool up phase. That´s one reason why the Jumo-004 B-1 had around 10-25 hours lifetime while the -004 B-4 had around 25-50 and the BMW-003 around 200.
