Magnesium and Gasoline?

I was pondering the other day with a friend why they never made carbs out of magnesium, and only the rare manifold or blower case was Mag. Why wasnt it more common? Does gasoline attack or degrade magnesium? Thanks for the info.

 

When magnesium catches on fire it is very difficult to extinguish and burns extremely hot. It can't be put out with water. It has to be starved of oxygen by chemical agents such as foam.

http://www.blazetech.com/Products___Services/Fires_and_Explosions/Magnesium_Fire/magnesium_fire.html

 

It's also reasonably difficuly to light in a solid chiunk. Mag dust or powder will explode, but a block takes a bit to get burning. Much more than a backfire would produce. Even Nitro blower explosions don't come close to lighting Mag blower casings.

 

I would guess it has to do with casting tecniques(sp). That would make for one expensive carb also.

 

Pot metal is commonly used because it's so cheap. Pot metal and aluminum are both easy to use when you're making die castings. Magnesium is best suited to sand casting, which wouldn't provide the precision needed for a carburetor body.

There's lots about magnesium on http://www.roadsters.com/wheels/

Dave Mann
(602) 233-8400 weekdays
http://www.roadsters.com/

 

Levi Jones of Jones Engineering (Jones Rear ends) cast at least Mag SBC block

 

Thanks for the info. VW engine and transaxle cases are die cast Mag, so it can't be all that hard to do properly. I got to thinking about carbs and intakes because my friend is a roundy round racer. some of those guys go through extream lengths to save weight, things like machining half the bolt heads off. The lighter they can make the car, the more they can put weight exactly where they want it to bring them to the minumum weight. A Mag carb that is a pound lighter is a pound ther can put somewhere else, and I'd never, ever heard of a Mag carb.

Sounds like it's a manufacturing issue, not a problem with the metal it's self.

 

Dellorto built some magnesium carbs for motorcycles, but they're pretty rare...

 

Blocks and Transaxles are machined after they're cast.

 

Probably has something to do with the cost (hard to believe when you consider what a carb can cost these days...) Aluminum will burn too, but it too is hard to ignite.

Flatman

 

Magnesium has poor corrosion resistance,
and is much more expensive for manufacturing.

For real serious racing applications,they are more
interested in the weight savings.


If you want to make a light weight carb,
look at casting them from light weight Polymer.

Even then,you are not going to save much weight.

 

From what I have learned reading and observing about magnesium:

The weight savings over a similar aluminum casting is quite a bit on larger items but when you factor in cost the savings are negligible unless you are using aircraft grade aluminum.

Magnesium castings(early ones anyway)had a tendency not only to be porous but also had,"hard" spots in them which not only made machining more difficult ,the hard spots had a tendency to be prone to cracking.Polishing magnesium was more difficult as well as a bit on the dangerous side if you were removing metal with a grinder.

As Ian stated,the corrosion resistance of magnesium is very poor whereas aluminum;when the surface has been disturbed,tends to form an oxidate almost immediately which acts as a corrosion barrier.

I had a set of magnesium wheels for my Mini and they leaked air constantly to the point that I finally got tired of trying to seal them and turned them into hose racks in my shop.They made poor hose racks too.

Just my twopence