BMW801 Altitude Performance

[davebender]

It's well known that the DB605 engine had good performance at high altitude. Why couldn't the BMW801 engine achieve similiar performance by copying the proven DB605 supercharger and hydraulic coupling arrangement? Just scale it up a bit as the BMW801 engine had a greater displacement.

 

[Colin1]

I don't think they really looked at it.
They tried bolting two 801s together and came up with something whose performance didn't justify the complexity.
They then tried adding cylinders but in all honesty I think BMW's engineers were just looking at bigger engines than the 801 as the next logical development eg the 802 featuring novel systems such as the three-stage supercharger; performance figures were impressive but I'd need to dig those out. In late 1943 even that was abandoned.