Editing BMW 801 (section)

=== Supercharger development ===
[[File:BMW801 Kommandogerät (1939) MTU-Museum 20231112 08w.jpg|thumb|BMW-Kommandogerät, a single-lever power control device for the BMW801, designed by Heinrich Leibach.]]
With the engine being used in higher-altitude fighter roles, a number of attempts were made to address the limited performance of the original supercharger. The BMW 801E was a modification of the D-2 using different [[gear ratio]]s, of 6:1 at low speed and 8.3:1 at high speed, that tuned the supercharger for higher altitudes. Although takeoff power was unaffected, cruise power increased over 100&nbsp;hp (75&nbsp;kW) and "high power" modes for climb at nearly 1,500 to 1,650 PS; and combat were likewise improved by up to 150&nbsp;hp (110&nbsp;kW). The E model was also used as the basis for the BMW 801R, which included a much more complex and powerful two-stage four-speed supercharger, as well as [[Die casting|die cast]] [[hydronalium]] [[cylinder head]]s, strengthened crankshaft and pistons, and chromed cylinders and exhaust valves; it was anticipated this version would produce over {{convert|2000|hp|kW PS|abbr=on}}, or over {{convert|2600|hp|kW PS|abbr=on}} with [[MW 50]] [[methanol]]-water injection.<ref name="Christopher, p.81">Christopher (2013), p. 81</ref>

The 801R, with its 2-stage, 4-speed supercharger, had a critical altitude of 11,000 meters. Above that altitude, the R could use additional boost by nitrous-oxide (GM-1) injection. The R was also bi-fuel. At its critical altitude, the R could deliver 1,400 PS.<ref> Gersdorff (1995), p. 66 </ref>

In spite of these improvements, the E model was not widely used. Instead, continued improvements to the basic E model led to the BMW 801F, which dramatically improved performance across the board, with takeoff power increasing to 2,400&nbsp;hp (1,790&nbsp;kW), making the 801 the only German aviation engine of an existing type that had a producible subtype that could [[Luftwaffe#Engine development|exceed 1,500 kW]] from a proven military aircraft powerplant. It was planned to use the F on all late-model Fw 190s, but the war ended before production started.

The 801F's supercharger had higher critical altitude, than the earlier D-2 series. The improved gear ratios increased the engine's critical altitude to between 7,000 and 8,000 meters. The 801F also had a stronger crankshaft and a fuel-injector pump of higher capacity. The version also had larger intake- and exhaust-valves, with increased valve-overlap. The engine, in the TF powerplant form also had better internal and external aerodynamics. On the test bench, the 801F could deliver 2,600 PS in 1945.<ref> Gersdorff (1995), p. 66 </ref>

The 801F was 25 centimeters longer, than the earlier 801 versions. The reason for this was to keep the balance of gravity of the Ta 152 aircraft.<ref> Gersdorff (1995), p. 66 </ref>

In 1944, the strongest production version of the 801, the 801S went into production. It had the same gear ratios, as the 801E, and it's supercharger used swirl-throttling. It used the parts of the earlier D-2, and in some parts, the above mentioned more advanced versions (E and F). The S also had an improved and simplified master controller and different magneto timing. The 801S also had altered valve-timing. In special-emergency mode, it could deliver 2,200 PS at sea-level.<ref> Gersdorff (1995), p. 66 </ref>