New BMW 3 series has a magnesium block

[Alan]

What are the advantages of going with this instead of iron or aluminum?

 

[moribundman]

Magnesium is lighter than aluminum.

 

[JHZR2]

Is it just one or two of the fancier engines that have this? Ill bet the lower priced models keep the older technology, but maybe not!

Thanks,

JMH

 

[Alan]

From what I read it sounds like all of them are going to Magnesium.

 

[shortyb]

quote:

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Originally posted by moribundman:
Magnesium is lighter than aluminum.

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And stiffer per weight/volume. Allows pieces to be thinner while retaining needed strength.

Just don't let it catch on fire though, hard to extinguish. We used to encounter folks that would use coffee creamer that contained magnesium to make fires.

JHZR2-From what I've read, all the gas E90 engines coming to the states will have Mag blocks.

 

[Matt_S]

quote:

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Originally posted by shortyb:
Just don't let it catch on fire though, hard to extinguish. We used to encounter folks that would use coffee creamer that contained magnesium to make fires.

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Yeah, and it's extremely intense, too. You can't look at it, it's so bright.

 

[John K]

Did you see the writeup posted yesterday by 427Z06?
Good description of it.
http://www.sae.org/automag/techbriefs/01-2005/1-113-1-20.pdf

 

[XS650]

quote:

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Originally posted by shortyb:
And stiffer per weight/volume. Allows pieces to be thinner while retaining needed strength.

Just don't let it catch on fire though, hard to extinguish. We used to encounter folks that would use coffee creamer that contained magnesium to make fires.

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Magnesium alloys are only about 60% as stiff as Aluminum alloys. Magnesium is lighter though, so thicker sections are used to make up for it's lower stiffness and it still comes out ahead.

It also has the advantage of being a good energy absorber, so dampens noise better than aluminum.

There have been other engine with magnesium alloy blocks or major hunks of magnesium alloy in the engines. It's not much of a fire hazard unless it is finely divided, like maching swarf.

Type 1 and 3 VW engine cases and transmission housings were magnesium alloy and didn't normally turn into super novas, even when the entire car burned.

 

[shortyb]

quote:

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Originally posted by XS650:
Magnesium alloys are only about 60% as stiff as Aluminum alloys. Magnesium is lighter though, so thicker sections are used to make up for it's lower stiffness and it still comes out ahead.

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I need to brush up on my metallurgy

. It may be the lb. for lb./stiffness ratio that I was thinking of.