Conrod Dimensions

[Turbo-Brown]

Don't suppose anyone knows what the following dimensions for an M20B25 rod are do they:

Big End Diameter:
Gudgeon Pin Diameter:
Distance between centres of pins:
Big end Width:
Little end width:

Cheers!

Alex

[oze30]

which one??

there's 3 diff 2.5 early, late( not sure if there is a diff, and 525e, which is a 2.5/2.7 (???) I can measure, but someone will prolly get there before me!

[e30_Turbo]

Don't suppose anyone knows what the following dimensions for an M20B25 rod are do they:

Big End Diameter:
Gudgeon Pin Diameter:
Distance between centres of pins:
Big end Width:
Little end width:

Cheers!

Alex

Now what are you upto?

[Turbo-Brown]

which one??

there's 3 diff 2.5 early, late

Aah now there's a question. The 2.7 ones I guess if there's a difference in the lengths over the three types?

Cheers!

Now what are you upto?

Just thinking out loud at the moment as I'm hopefully off to look at a new shell from Brown this weekend which would give me a spare 2.5 engine to play with if it's worth buying the car

The next question is:

How much work is involved in getting an M50 crank into an M20 block and are the M50 cranks forged?

Don't want to increase the stroke, and if it went down a little bit I wouldn't be too bothered although that throws the length of the rods out the window, and probably various other roddy type dims too so the original question might be out the window anyway.

[WillG]

i dont think they are forged, to get the crank to fit i think you need to get a sleeve made for the front and interference fit it and thats it, i think you will want the short 130mm rods from a M20B20 the B25 ones are 135mm

[WillG]

has anyone got a link for that BMW engine spec database done by dave massenhaur (sp) ive posted before, ive had to reformat and I forgot to save all my links

[Turbo-Brown]

Figure if you're gonna play about with these things then you're getting off going to the biggest rod/stroke ratio you can, and if the stroke ends up being a little bit less, you can rev it more.....with the right crank, rods and pistons etc

[e30_Turbo]

No doubt you'll just make the parts you need anyway

IIRC the M50 pistons are teflon coated or something like that, M42 pistons are forged tho