I need a set of 135mm rods. What will be the best set to get on a budget? As far as lightweight and strong, going in a m50
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Originally posted by nando View PostALL RODS ARE FORGED!!!
;)
S52 rods are a little bit lighter than M52 rods, but either would be fine.
You are 100% correct. All rods are forged - I too hate it when people for some reason think that some connecting rods are cast instead of forged....
However, not all forging is the same. M50, M50TU, M52 and M52TU all use conventionally forged rods but the M54 uses 'fracture split' forged rods which is a mildly compromised style of manufacturing that saves on costs.
Not saying that M54 rods are weak, its just that they are not as strong as M52 ones.
Proof here:
Skip to the summary and read the conclusions. When the writer is refering to powder forging, he is referring to what BMW calls 'fracture splitting'.
One key finding is that traditionally forged rods were found to have 37% higher fatigue strength. I am not an engine builder or a physics student but that to me sounds like the traditionally forged rod is the way to go.Leo.
E30 318iS, E36 328i
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Originally posted by Leo_328i View PostNando,
You are 100% correct. All rods are forged - I too hate it when people for some reason think that some connecting rods are cast instead of forged....
However, not all forging is the same. M50, M50TU, M52 and M52TU all use conventionally forged rods but the M54 uses 'fracture split' forged rods which is a mildly compromised style of manufacturing that saves on costs.
One key finding is that traditionally forged rods were found to have 37% higher fatigue strength. I am not an engine builder or a physics student but that to me sounds like the traditionally forged rod is the way to go.
Just before people start freaking out about misquoted engineering principles, a bit of perspective is in order.
Certain materials, like steel, have a fatigue limit. Below this limit, the material can cycle between its max/min stresses indefinitely. If it is designed improperly, the loading conditions will not always stay below the strength limit, and will eventually fail.
Certain other materials, such as aluminum, do NOT have a fatigue limit. They will eventually fatigue and fail, and there is nothing that can be done from a design perspective to stop this from happening; it's a material property.
However, the number of cycles is typically in the tens of millions, and there are significant safety factors on the relevant parts so that the calculated fatigue limits or #cycles to failure are conservative.
Main point: don't worry about fatiguing rods in an NA engine. More strength doesn't necessarily mean more better.
S5x engines with original rods are known to go for 250k+ miles without issue. You will NOT have an issue with any oem rod.
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for a NA build, pick the Lightest Oem rods.
street engine builds of M50 family dont get into the RPM range to stress an OEM rod to break.
the Fracture split rods are very light and cap fit to support bearing structure is PERFECT..... I don't see NA engines killing rods- just valves and rod bearings.OBD1 M54/M52TU swap as a M50b25
Z4 non powered steering rack fits e30
Euro e46 2005/6 320d 6mt gearbox into E30 with M20 hardy and beck 1985 327s engine
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