Quick Rod info needed..

[MonkeyMadness]

Hey guy's I don't have one on hand to check, So here goes..
Whats the I.D. mesurments of the big and little end
of the M20B25 Rod....

mm or inch...

thanks :D





55/23
2.165/.905
w.842
---------
??/22
?.???/.866
w.???

[whodwho]

From some notes I had:

Pin Diameter:    .866" 22mm
BE Bore:        1.890" 48mm
Length:         5.315" 135mm
BE Width:        .858" 21.79
 
M40B18       138mm
M42          140mm/609grams 
M50B25TU:    140mm/675
M52B25:      135mm/575
S50          135mm/540grams
M20B25       135mm/600-640?grams(2.5) 
M20B27       130mm/617grams(2.7)
M54B30       145mm
 
Titanium rods  360 grams. 
Eagle rods     540grams.
Pauter rods    500grams (S50 or M20).
Crower rods    520grams (though they make a 495 gram rod too).

[MonkeyMadness]

Wow
thanks...

Hey whodwho..

I'm done with the loaner head. Let me know when you would like me to meet you for drop off...

[whodwho]

Sounds good

[jlevie]

From some notes I had:

M20B25       135mm/640grams(2.5) 87-91
M20B25       135mm/600grams(2.5) 91-92

Hmm, realoem.com shows the same rod part number for all production of M20B25 engines. I know that BMW started using a lighter weight piston from 6/88 on, but I don't see any different rods being used.

[whodwho]

You know I didn't remember seeing that myself and was surprised to read that as well, it has been awhile since I had done that research and looked at that doc.

I'm not sure where I came across that and am not one to spread info without being able to back it up. I question that myself, I will edit it out. ;)

[whodwho]

From some notes I had:

M20B25       135mm/640grams(2.5) 87-91
M20B25       135mm/600grams(2.5) 91-92

Hmm, realoem.com shows the same rod part number for all production of M20B25 engines. I know that BMW started using a lighter weight piston from 6/88 on, but I don't see any different rods being used.

So I stumbled across where I found those figures, now I am confused more then ever...




I found it in the MM catalog, so I would take that as reliable source but I can't say I have seen that style rod come out of a M20 and as noted above the parts catalog doesn't show a difference.

Can anybody backup it up that they have pulled that style rod out of their M20??

[nando]

I can only find one pn for m20b25 rods, 11241288386. Even counting m20's built in 1993.

You could always call them and ask- maybe they meant m50?

[whodwho]

More of a curiosity thing for me, I have a set of M50tu(140mm) that I will be using. Which interestingly has a similar beam to the one in that MM pic and that I believe is the 'unknown rod' in his first post.

[nando]

Their other # have been reasonable. I have a couple sets of s52 rods.

[Knockenwelle]

My M20 is the numbers-matching original motor from my '91. After building the motor myself, I can tell you 100% that my rods are the #4 in the above pic (with BIG balance pads on the big end). I recall being quite impressed at their stoutness, though maybe a little disappointed in their weight.

FYI-without any work other than big-end resizing, all 6 rods weighed within 1.5 gram--both recip AND rotating. Props BMW!!

[e30guydownunder]

More of a curiosity thing for me, I have a set of M50tu(140mm) that I will be using. Which interestingly has a similar beam to the one in that MM pic and that I believe is the 'unknown rod' in his first post.

It looks awfully like an E30 M42 rod, these are 140mm also and the casting numbers look very similar to mine. Either way same same. My M42 rods are 589grams.