s52 and m52 rods the same???

[nattybumpo]

are they the same??? I've read they are the same then some disagree....

[ZiMMie]

They are different.

[nattybumpo]

what happens if I use s52 rods and pistons with an m52 crank....keeping in mind that I bore the crank.

[PiercedE30]

what happens if I use s52 rods and pistons with an m52 crank....keeping in mind that I bore the crank.

Planning on putting a big hole in the crank?

[SpecM]

Planning on putting a big hole in the crank?

-hehe I think he means "block".

-To the OP: I'm assuming you want to use a 84mm crank? (m52b28 )

[BimmerToad]

what block are you running? A M52 block probably won't withstand the S52 size pistons.

328 and S52 rods are the same length, 135mm, but the S52 rods are slightly lighter.

Your compression ratio is going to be pretty low, since you're moving the TDC and BDC piston height down by 3.5mm (S52 crank 91mm - M52 2.8 crank 84mm)/2

edit: or is the S52 crank 89.6mm stroke? 2.8mm change in TDC

[nattybumpo]

lol yeah I meant block....yeah so all I need to know is if the rods are physically the same. I thought all the rods were 135mm....Is it safe to use the s52 rods with the m52 pistons?

[erik325i]

what block are you running? A M52 block probably won't withstand the S52 size pistons.

Why wouldn't a m52 block not be able to withstand s52 sized pistons? I was under the impression that all of the US m50/m52/s50/s52 blocks were the same besides the bore size?

-Erik

[BimmerToad]

Why wouldn't a m52 block not be able to withstand s52 sized pistons? I was under the impression that all of the US m50/m52/s50/s52 blocks were the same besides the bore size?

-Erik

Paging Stu McHenry .... :)

From what I've read .... from Stu's posts,

Engine Block Allowable bore size (average)
M50 NV 86mm
M50TU, M52 85mm
S50, S52 87mm

The S50, S52, and non-vanos M50 blocks are thicker than the vanos M50 and M52 blocks. Keep in mind there are some blocks that are 'healthier' than others, i.e. can be punched out further.

FWIW, this is my understanding, through other people's posts, not my own observations

[erik325i]

Maybe you're thinking of the aluminum block m52 which can't be bored out?

-Erik