[F87source]

Originally Posted by M Fifty

Extra Grist to your Mill: The rods on the M2 are used on the M235i Racing, and the M4 GT4 (where they replace the earlier design). Two hypotheses arise from this, that require testing with physical evidence: 1. BMW is fitting the cheapest parts possible in the knowledge that race teams will replace them with items that are fit for purpose. 2. They are fit for purpose as is (and, that might mean they are forged, but might not).

In the meantime, hopefully the knowledge that someone on the internet is WRONG, isn't keeping you awake...

The m235ir is detuned for cooling purposes as it runs endurance races so power and durability isn't an issue. M4 gt4 makes around ~431 bhp as per bmw iirc so nothing crazy compared to the standard s55. It just means the rods are strong enough to handle it.

It isn't proof of anything.



I'm not saying it definitely isn't forged, my stance is there isn't any proof that is substancial that it is forged. So I'm personally not willing to believe it's forged and spread rumours about it until it's proven. So I came here to see if anyone had proof of forging.


Also it's not that the posts are "wrong" (they could be right they could be wrong it is yet to be determined) as currently the construction of the rod isn't fully determined yet, it's more to do with the fact that someone is willing to state for a fact and act like their word is final that the rods are forged based on terrible sources and poor real OEM cross referencing that I'm here to correct. I personally don't have a solid stance to whether the rods are forged or cast, I'm here to seek solid evidence and will offer my counter opinion when I see poor sources.

Do I care so much I'm loosing sleep, absolutely not, I'm personally interested in investigating this topic so I'm posting meaningful rebuttles.

[boldy1]

Originally Posted by F87source

Btw your article still states that the m2 had a closed deck block. So that should show the quality of the source you presented. So you may not have time for internet derailing of this thread, neither do I. So make sure you do a better job with your information otherwise the same talking points will have to be rehashed. Because your real OEM info was wrong and your review article doesn't seem so trust worthy.


I'm not trying to start some crazy argument I'm trying to see if the m2 really does have forged rods and I personally really don't think it does - and I really hope I'm wrong.

Edit - that article also says the m235i has a standard iron crank shaft implying that isn't forged.... So yeah a pretty crappy source imo.

i have a set of standard rods in the M2 rods in the garage. do you want some pictures

[F87source]

Originally Posted by boldy1

i have a set of standard rods in the M2 rods in the garage. do you want some pictures

For real?

Yeah I would love to have some pictures, side profile, rod cap, and front on if you could. Essentially as many pictures as possible.


However even with those images I am not an expert enough in metallurgy to tell 100% if it is forged or not without a cast reference. But it would be better than any pictures I have seen so far.


On the n55 crank shaft it is easy to tell if it is forged or not because you have characteristic traits of forged crank shafts: the wide parting marks, the rounded counter weights, and a comparison between a casted version which shows the distinction between parting lines and counter weights to affirm that.

[F87source]

Originally Posted by boldy1

i have a set of standard rods in the M2 rods in the garage. do you want some pictures

Get me images like this: https://www.ebay.co.uk/itm/174275260503

This is an n54 rod (literally the best example of rod pictures - no oil, no discoloration, very clear and shows the side of the rod up close unlike every other image I have seen so far) if the parting lines are similar and go to the rod cap as well, then it will highly likely (more likely than with one source alone but I still wouldn't trust my own judgement 100% and if there are bmw technical documents too that would bring the confidence to 100%) the m2 n55 has forged rods as well just like those sketchy sources say.

[ried]

How many rods have M2s thrown?

[M Fifty]

Originally Posted by F87source

The m235ir is detuned for cooling purposes as it runs endurance races so power and durability isn't an issue. M4 gt4 makes around ~431 bhp as per bmw iirc so nothing crazy compared to the standard s55. It just means the rods are strong enough to handle it.

It isn't proof of anything.



I'm not saying it definitely isn't forged, my stance is there isn't any proof that is substancial that it is forged. So I'm personally not willing to believe it's forged and spread rumours about it until it's proven. So I came here to see if anyone had proof of forging.


Also it's not that the posts are "wrong" (they could be right they could be wrong it is yet to be determined) as currently the construction of the rod isn't fully determined yet, it's more to do with the fact that someone is willing to state for a fact and act like their word is final that the rods are forged based on terrible sources and poor real OEM cross referencing that I'm here to correct. I personally don't have a solid stance to whether the rods are forged or cast, I'm here to seek solid evidence and will offer my counter opinion when I see poor sources.

Do I care so much I'm loosing sleep, absolutely not, I'm personally interested in investigating this topic so I'm posting meaningful rebuttles.

I didn't offer the observation as proof of them being forged (or not), but as a suggestion that either way they are considered fit for purpose. Plus, if the first thing the race teams do is change them, BMW may as well fit something that's as cheap as possible. HTH

[F87source]

I was looking around tonight and stumbled upon this:
https://www.bim merboo st.com/showthread.php?96803-Maximum-PSI-offering-forged-S55-pistons-and-rods-for-F80-M3-F82-M4-and-F87-M2-Competition]

(Remove the spacing)


If you scroll down enough you'll see the side of the s55/n55 rod on the right and there you'll see the parting line which does look pretty wide. And imo (not an expert so I still could be wrong) it looks like it is indeed a forged parting line.


So the stock rod looks to be a powdered metal factured-forged connecting rod.


SeanWRT my apologies for grilling you on your poor sources (didn't mean to be a dick before I just wanted to also get to the bottom of this with accurate information), but it looks like although that article was riddled with alot of misinformation it was correct about the rod.

Also if you look at the numbers on the rod and compare it to the n54 rod from my ebay link, they're different rods like what I stayed earlier. However they're very similar in design.

[murderspice]

So the only material difference between the n55 and the s55 is the block? Would that account for the sound difference?

[F87source]

Originally Posted by murderspice

So the only material difference between the n55 and the s55 is the block? Would that account for the sound difference?

The sound difference between the s55 and n55 is mainly due to the use of 2 turbos (turbos are the major factors affect sound), 2 down pipes, and unequal length mid pipes.