DB605D...7.5/8.5CR?

[schwarze-man]

Can anyone show references to confirm the compression ratio of late mark DB605 versions please?
I have the original motorenkarte 9-605 DB u. DC from Dez '44 and this makes no reference to CR at all. Likewise, the DB605D Ersatzteilliste dated Dez '44 shows no reference to different parts for different engines of the type and, lists the CR as 1:7.3/7.5.
Any info appreciated.

SM

[jarecki71]

Hi Schwarz-man

I looked through the DB engine manuals 605 A, B, C,(different dates of issue) and is given compression, the right side is 1:7.3 left 1:7.5

Regards

Jarek

[cjme201262]

I have always been interested as to why they should be different - given that also means ofcourse mixture settings etc. would vary (port/starboard) to suit as well ?

[innocenti]

I think it is to compensate the different length of the air ducting of the side mounted supercharger to the cylinderbanks.
innocenti

[schwarze-man]

Thanks for the replies! Yes, I am sure that the difference is related to the effect of the offset of the inlet flow. The other big difference is the often quoted 8.3/8.5 CR of some engines, I am having difficulty finding any original reference for this, despite some quoted figures. Such a difference from the 7.3/7.5 CR would require different components and I have yet to see this.