forged magnesium crankshaft??

[8600RPM]

Www.bmwusa.com/bmw/m/m4

If you read about lightweight component tab it says the s55 has a forged magnesium crankshaft? First I've heard. That true?

[jwilliams]

Well BMW have said it. I doubt they can and it not be true as they would be ripped a new one.

Its had allot of parts strengthened and designed for lots of power till redline.

All the S65 "our averagely built under powered V8" guys will find a reason why a magnesium crankshaft is worse than their average cast one. Lol

Bmw put allot of work into the S55 things like a magnesium crank wouldn't surprise me.

[YasM3]

I just skimmed through my S55 training manual. It clearly states the crankshaft is a forged steel unit that is a few pounds lighter then the N55 crankshaft. The manual may be wrong but this is a training manual direct from BMW. I do not know why they would post on their main website that it is a magnesium crankshaft though if it were not. I will have to try to dig deeper into it to find out.

[CaryTheLabelGuy]

Originally Posted by darge82

I just skimmed through my S55 training manual. It clearly states the crankshaft is a forged steel unit that is a few pounds lighter then the N55 crankshaft. The manual may be wrong but this is a training manual direct from BMW. I do not know why they would post on their main website that it is a magnesium crankshaft though if it were not. I will have to try to dig deeper into it to find out.

That website also states that the twin turbos are Twin-Scroll. I didn't think they were.

[8600RPM]

I mean its obviously a marketing team and I would have just blown it off however a couple things.

1. It uses the specific wording of "forged out of a single piece of magnesium" or something like that which is pretty specific.

2. In an interview with one of the head M guys on one old article, he was quoted as "almost in tears like a proud father describing his son" or some b.s when he was talking about the forged crankshaft and how special it was in design.

I am sure they would have been more likely to talk about this for marketing given they talk about the magnesium pan but nevertheless would be quite cool.

It is quoted as being 2-3 KG lighter than the n55 which is 5-6 pounds. For the size, that seems like a fair amount of weight.


Anyway, would be a cool, unique feature.

[YasM3]

Originally Posted by CaryTheLabelGuy

That website also states that the twin turbos are Twin-Scroll. I didn't think they were.

Exactly that is not correct. They are mono scroll turbos.

Originally Posted by 8600RPM

I mean its obviously a marketing team and I would have just blown it off however a couple things.

1. It uses the specific wording of "forged out of a single piece of magnesium" or something like that which is pretty specific.

2. In an interview with one of the head M guys on one old article, he was quoted as "almost in tears like a proud father describing his son" or some b.s when he was talking about the forged crankshaft and how special it was in design.

I am sure they would have been more likely to talk about this for marketing given they talk about the magnesium pan but nevertheless would be quite cool.

It is quoted as being 2-3 KG lighter than the n55 which is 5-6 pounds. For the size, that seems like a fair amount of weight.


Anyway, would be a cool, unique feature.

The training manual states that the new crankshaft is indeed lighter. It also goes over what NEW parts were used on the S55 and what parts were carried over from the N55 as well. Its pretty indepth. I believe the crank was said to be 4#s lighter then the N55 crank. 4#s off of rotating mass is actual a big difference.

[Mike@N54Tuning.com]

Originally Posted by jordon335

Well BMW have said it. I doubt they can and it not be true as they would be ripped a new one.

Its had allot of parts strengthened and designed for lots of power till redline.

All the S65 "our averagely built under powered V8" guys will find a reason why a magnesium crankshaft is worse than their average cast one. Lol

Bmw put allot of work into the S55 things like a magnesium crank wouldn't surprise me.

Interesting as I've heard of a few of the S55 motors are having VANOS issues spinning the pulley on the crank and that a recall may be coming down the pipeline like the older N55 motors had.

Mike

[YasM3]

Originally Posted by Mike@N54Tuning.com

Interesting as I've heard of a few of the S55 motors are having VANOS issues spinning the pulley on the crank and that a recall may be coming down the pipeline like the older N55 motors had.

Mike

Was that 1 isolated issue or multiple? Also where did you see/hear this if you do not mind.

I have yet to see these issues first hand or hear about them.

[8600RPM]

4 to 5 pounds at 7k rpm and above is alot.

If you consider how light the stock wheels are, Cf driveshaft, decreased drag from no hydraulic steering, alternator disconnect and some other lighter parts in engine, I wonder if that explains why it's putting wheel power that is so high? I'm sure it's under rated too but even if it were 440 bhp but you eliminated a bunch of parasitic loss, the whp would be much closer to crank.

Originally Posted by darge82

Exactly that is not correct. They are mono scroll turbos.



The training manual states that the new crankshaft is indeed lighter. It also goes over what NEW parts were used on the S55 and what parts were carried over from the N55 as well. Its pretty indepth. I believe the crank was said to be 4#s lighter then the N55 crank. 4#s off of rotating mass is actual a big difference.

[8600RPM]

After reading around the net, it seems exceedingly unlikely this is true given I can't find one example of this in any car application ever. Only husky chainsaws appear to be testing this technology lol. Damn marketing people. It sounded good I'll give them that

[Mike@N54Tuning.com]

Originally Posted by darge82

Was that 1 isolated issue or multiple? Also where did you see/hear this if you do not mind.

I have yet to see these issues first hand or hear about them.

3-4 that I've heard of on unmodified cars alone and some involving motor replacement as a result.

Mike

[CanAutM3]

I seriously doubt that it is. IMO magnesium is not an appropriate material for a crankshaft.

[SakhirM4]

http://www.bmw.com/com/en/insights/t...ylinder_engine

This article about the BMW I6 motors talks about the use of lightweight components such as an aluminium-magnesium alloy crankshaft .....

[8600RPM]

perhaps the new b58 engine and s55 do have aluminum magnesium cranks. Go figure!

[Stilakazam]

It looks like they are technically not lying. The training doc says the crankshaft is made of forged steel alloy. More specifically it is made of 42CrMoS4.

If you look here: http://www.steelnumber.com/en/steel_...hp?name_id=195

You can see that Magnesium (Mn) is part of the chemical composition, albeit a small one.

[8600RPM]

Magnesium is Mg. Mn is manganese. This looks like chromoly steel which is still a lighter weight type. No magnesium at all it appears. Strange

[8600RPM]

Cromoly is a cheap and disapointing material. Marketing people probably realized this snd decided a single piece magnesium crank sounded much more advanced which it does!

So there goes that hope. That would have been cool

[Stilakazam]

Originally Posted by 8600RPM

Magnesium is Mg. Mn is manganese. This looks like chromoly steel which is still a lighter weight type. No magnesium at all it appears. Strange

Hah oops got my periodic table values wrong.

[CanAutM3]

Originally Posted by SakhirM4

http://www.bmw.com/com/en/insights/t...ylinder_engine

This article about the BMW I6 motors talks about the use of lightweight components such as an aluminium-magnesium alloy crankshaft .....

I wonder if that is not a typo, where they meant crank case rather that crank shaft. A crankshaft is highly solicited from a stress point of view.

[SakhirM4]

Originally Posted by CanAutM3

I wonder if that is not a typo, where they meant crank case rather that crank shaft. A crankshaft is highly solicited from a stress point of view.

That makes a lot of sense.

[8600RPM]

Lesson learned: give your marketing team a primer on basic car parts

[oldmanstyle]

Originally Posted by 8600RPM

Cromoly is a cheap and disapointing material.