I notice most of the string trimmer engines that I encounter. The crankcase and cylinder are made of very brittle material that can be broken off very easy, like plastic. If you crash with this kind of engine, it must be broken into pieces!! What kind of alloy is that, any name for those alloy ( I know is call el cheapo )? Do you know of any brand that have stronger crankcase material. I heard from someone in lawn forum that Stihl 4Mix crankcase use some sort of aluminum magnesium alloy that is stronger but I am not sure.

Any information?
Thanks

The major brands all have very good material. Echo, Stihl, Husqvarna are all very nice. Even the cheaper brands can work. Look at it this way, if you crash a $20.00 motor and it breaks you can make another one. Also unless you drive it in nose first you usually come out pretty well. Maybe a bent muffler stack.

I believe the material you are referring to is commonly called "pot metal". It's the same stuff kids cap guns are made of and is usually made up of various grades of recycled aluminum and then cast which make it very brittle. I personally don't know of anyone using it in a purpose built aircraft engine and find that most aircraft engines are a good grade of cast or machined aluminum such as 6061.

I have Echo Vortex engine and Shindaiwa T260 engine. They both were very brittle. Do you know the name of that kind of alloy?

You mean those are suppose to be good material already?!!!! I would like to see what is the bad ones!!


Thanks

I have 2 Brison 3.2 engines. They are both older models and one is a bit older than the other (1990?).Both crankcases are of excellent quality but the cylinder/cooling fins on the newer one is made of a much higher quality metal. The older cylinder is very brittle but runs like a fanny full o' corn I treat/fly them like full scale airplane engines... Just don't crash em'!

THe material that most engine cases are made of is an alloy of Aluminum and magniseium (wish I could spell them big words)

Some of the newer engines do if fact have a brittle nylon, type plastic as part of the case.

Don//

I can testify that if you convert enough different engines and creat enough sparks eventualy you will find one made from magnesium. POOF![X(]

Hi altavillan
What do you mean, that you have not seen magisium alloy? May be that is why the crankcase are so brittlle. How can you tell without cracking them whether it is magnesium alloy? Color difference.

Well you start cutting but you don't see the hard bolt thats gona dull your saw blade real fast. The blade heats up and so does the aluminum looking stuff you are cutting and the next spark....... the aluminum which is really magnesium in camoflage turns into a torch. I think it was a 70s vintage Stihl saw.

Would someone look up how to spell Magneserium pls

Magnesium. Very hard to put out once it starts burning too. Ask me how I know. [X(]

Not as hard as white phosphorus[8D]

All the cast cases start out brittle. How you break them in determines if they stay that way. That's what all the heat cycling is for during the break in.

White Phosphorus is easy, copper sulfate puts that out but ya need one of those yellow fire extinguishers for magnesium and titanium. Set a 5 axis CNC mill on fire machining magnesium aircraft parts. Must have set titanium on fire a hundred times. Makes great fire starters if you get the real fine wooly chips!! LOL