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BMW M51 Questions
silverzx Offline
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Location: Bristol (England)
#1
BMW M51 Questions
Hi all, I have recently acquired a M21 mechanical inline pump.

Are these a straight swap with a M51 electronic inline pump? Obviously when converting I'd need a 3 series accelerator pedal and cable, is anything else required?

[Image: IMG_7019.jpg]


Next, I want to try run this pump (which will have a 12mm head) with my 12cm HX35. Is this just being over ambitious or is it likely to spool it? 

[Image: 12029101_1163339573681503_42192877_n.jpg]


Other plans are 3" exhaust, boost controller, large aftermarket FMIC, boost gauge, EGT gauge, external wastegate possibly, maybe water meth.

Lastly, I assume that for over 250 bhp I will need ARP head studs, does anyone know if any other BMW engines have the same size/thread/length head studs? ARP don't stock any directly for the M51.
(This post was last modified: 11-03-2015, 10:30 AM by silverzx.)
11-03-2015, 10:28 AM
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whitey1986 Offline
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Location: Scotland
#2
RE: BMW M51 Questions
What engine model/year do you have? If it is the earlier engine with alloy inlet manifold then you will need to make a spacer for the boss on the mechanical pump as it's like 2" dia whereas the later engine block has a 3.5" dia hole
03-05-2016, 01:16 PM
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whitey1986 Offline
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#3
RE: BMW M51 Questions
Sizes may not be exact but that's what you're looking for roughly
03-05-2016, 01:17 PM
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silverzx Offline
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#4
RE: BMW M51 Questions
(03-05-2016, 01:16 PM)whitey1986 Wrote: What engine model/year do you have? If it is the earlier engine with alloy inlet manifold then you will need to make a spacer for the boss on the mechanical pump as it's like 2" dia whereas the later engine block has a 3.5" dia hole

Well after some headache I figured this out for myself, upon pump removal I managed to snap one of the lugs (FFS it was so close to completion)!

Now I'm kinda set back a lot as I need another pump or need to repair this one. Would welding it likely damage internals?

Also, where would you get a spacer or what would you use to make a spacer to fit over the end of the pump?

Picture to show size difference of either pumps end, the mechanical one obviously needs a spacer and currently causing major oil leak:

[Image: IMG_6791.jpg]

[Image: IMG_6792.jpg]

Picture to show the snapped part of pump in question about welding:

[Image: IMG_6782.jpg]



Any help much appreciated to try finish this off.  Blush
06-14-2017, 06:44 AM
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silverzx Offline
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#5
RE: BMW M51 Questions
BUMP.
06-20-2017, 06:43 AM
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starynovy Offline
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#6
RE: BMW M51 Questions
Could be welded of only stripped to parts.. seals will burn. Spracer is simple ring turned on lather with notch for O ring to seal against block.
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07-01-2017, 02:51 AM
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