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View Full Version : How can a M50B20 be changed to M50B25?


Mordan
09-15-2008, 01:00 PM
This is a noob question, but I have found a very low mileage E36 320 and I'm thinking about buying it and taking its engine out and bring the 50k engine to my favorite chassis, the E34.

Could I do something to make the engine a 2.5 liter?

thank you.
russiankid
09-15-2008, 01:12 PM
From what I know you will have to bore the cylinders out to make it a 2.5L. I am not sure about the head.
Mordan
09-15-2008, 02:54 PM
From what I know you will have to bore the cylinders out to make it a 2.5L. I am not sure about the head.

ok forget it :) that's already not worth it. I might as well just find a M50B25.
whiskychaser
09-15-2008, 02:55 PM
Could I do something to make the engine a 2.5 liter?

thank you.

To increase engine capacity isnt really that simple. You are talking larger cylinders and pistons. Probably different con-rod lengths. Maybe even different crank, valves and cams. When you are looking at spending used engine type money it really isnt an option. If you have a 2.5 already I'd say spend the money on doing that one up or buy a recon. You at least sure its going to function with the fuel/ignition systems that are in the car

Edit: Seems my post was ill-timed and is redundant:D
Mordan
09-15-2008, 04:24 PM
To increase engine capacity isnt really that simple. You are talking larger cylinders and pistons. Probably different con-rod lengths. Maybe even different crank, valves and cams. When you are looking at spending used engine type money it really isnt an option. If you have a 2.5 already I'd say spend the money on doing that one up or buy a recon. You at least sure its going to function with the fuel/ignition systems that are in the car

Edit: Seems my post was ill-timed and is redundant:D

:) well dunno why but from the clouds of my memory, one BMW seller told me one day, something about the pistons (was it something else?) was common among many BMW engines.

does that strike a cord? :D
Ross
09-15-2008, 05:46 PM
Just speculation; I'll guess the block is a different casting between 2 and 2.5, the 2.0 cylinder walls won't be thick enough for the overbore.
whiskychaser
09-16-2008, 12:34 PM
I stopped being lazy and looked it up: The 2.0 and 2.5 have different bores and strokes: http://en.wikipedia.org/wiki/BMW_M50
And I'm pretty sure the head is different ( Ferret can confirm-IIRC he put an 2.0 on a 2.5 - until it blew up:D)
I'm sure Ross is right about boring out. There might be some common parts but I cant think of any right now:D