Mate and myself have been discussing BMW diesel engines a bit recently, the main topic being the M51 and M57 lumps.
Being well read on earlier petrol lumps he knows there's a good amount of interchangeability between the six cylinder engines, with the same basic block casting having been used since the advent of the M20 in the late 70's.
We're also aware that it's possible to fit the M57 in where an M51 came out, even dressing it with the M51 ancillaries.
This got us thinking a bit harder as to what internal differences there are between the 2.5 and 3 litre displacements, and how much is interchangeable.
Working on the theory that the M57 was available in both 2.5 and 3 litre form, is it doesn't seem beyond the bounds of possibility that the extra capacity comes from a longer stroke, and it could well be possible to build a 3 litre M51 with the crank and rods from an M57.
Perhaps someone with a little more knowledge on technical data/part numbers can shed some light on it?
Being well read on earlier petrol lumps he knows there's a good amount of interchangeability between the six cylinder engines, with the same basic block casting having been used since the advent of the M20 in the late 70's.
We're also aware that it's possible to fit the M57 in where an M51 came out, even dressing it with the M51 ancillaries.
This got us thinking a bit harder as to what internal differences there are between the 2.5 and 3 litre displacements, and how much is interchangeable.
Working on the theory that the M57 was available in both 2.5 and 3 litre form, is it doesn't seem beyond the bounds of possibility that the extra capacity comes from a longer stroke, and it could well be possible to build a 3 litre M51 with the crank and rods from an M57.
Perhaps someone with a little more knowledge on technical data/part numbers can shed some light on it?
