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With the popularity of m50/2 conversions to e21/30 and the short supply of e34 m50 sumps I thought I'd throw a couple of suggestions out for discussion.
M54 sump from e38/9, readily available in my local scrappy, has anyone tried them for size/ clearance? I'd heavily assume there wouldn't be any difference in the block between m50/2 and m54 so should bolt straight on and coming from an e39/8 they will have the bowl in the right position.

My next suggestion is a question, m20 and m50 cranks are interchangeable and I was lead to believe they were the same block. I could well be wrong but has anyone offered an m20 sump up to an m5x?

m20 sump is different
the e39 sump has the bowl in the wrong place.

its e34 sump (150 quid) or a complete dry sump conversion (2 grand+)

you have to cut the hell out of the e34 sump and then reweld it cos it hangs very low.

I honestly thought the e39 bowl was in the same place as the 34! Learn something new every day.

How different is the m20 sump? Would it be easier to cut the mounting face from an m50 sump and weld it on to the m20 sump (assuming that's where the difference lies?!) than to cut and re weld an e34 sump?

I spoke to my alloy welder / fabricator about this already. He said its probably easier CNC a flage and then create a whole new sump out of 4mm alloy sheet.. im not too worried about supply when they run out ill get some custom made from scratch.

I too like you had that thought, I was like well the m20 block is very similar to the m50 one so the pans must be very very similar. unfortunately the m20 although sorta looks like it will go, actually has a completely different kind of shape lol, I put the m20 pan on the engine it became quickly apparent its as much work as making one from scratch.

If you are after m50 sumps then im sure they still sell them at the dealer. although they are not very cheap,.