Got a few questions re/ the m103 2.6 vs the 3.0, my roommate is an MBZ mech and he says there the same but for some reason the head is not interchangeble -and cannot provide a reason why-. Before I get into the Q's, here is my objective: I want to bump the displacement of the 190e m103 2.6 motor (90'+) using OE internals.

1)What are the block differences other than cylinder size (deck height, main bearing width) between the 2 motors?

2)Barring any major unforeseen variances, could the 2.6 block be milled to accept the standard 3.0 piston -I think the 2.6 is 83mm and the 3.0 is 89-, is there enuff block material, would pin height be an issue?

3)What is the crank stroke and rod length difference?, basically could the 2.6 block be milled to accept the 3.o internals w/o changing compression?

4) If this simply wont work what in your opinion be the largest DEPENDABLE cylinder rebore for the 2.6 block?

Any and all comments and opinions are greatly appreciated, thanks for the great forum!
wayne

why not consider a motor swap. If your 2.6 is good you can sell it and pickup up a 3.0 103 engine. You may also consider a 104 engine 3.0 with a 24 valve head. Or turbocharge your 103. I,m sorry that I dont know if the engine can be bored and stroked but I am suggesting some alternatives.

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1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

As I understand it the bore is the only difference; which is why the heads won't interchange. You'd end up with unevenly mated surfaces (sharp corners) which could wreak havoc with detonation, pre-detonation, shock-wave fronts, etc; but ask any machinist if it can be done easily. You should be able to overbore a 2.6 to a 3.0 or larger as long as you address the heads and check the piston to rod fit. Check out,

http://www.renntechmercedes.com/

They over bore both a 2.6 and a 3.0 to a 3.6 with the same piston and rod set. I believe they mill the heads to accommodate the larger bore.