Casting Aluminum

[proparc]

Exactly what aluminum is used in our top stunt engine crankcases and pistons, i.e., PA's, Saito's,Stalkers etc.

[Tim Wescott]

Exactly the aluminum that's used.

That may seem like a wiseacre answer, but I suspect that it varies by manufacturer, by the date of manufacture, and a bazzilion other considerations.  If you happen to get a 'bar stock' engine the aluminum won't even be cast -- it'll be one of the 'four digit' alloys like 6061 or 2011 or something.

Further, at least some manufacturers are going to consider the details to be proprietary.  Choice of the alloy used and the post-casting treatment thereof has a big impact on the quality of the finished part, the reject rate, the expense of machining, etc.  Letting their competitors in on this knowledge would help the other guy build a better motor, or help him knock your own motor down in the marketplace -- these are both good reasons for wanting to keep the information under your hat.

In general, from what I know of cast aluminum, it'll be a heat-treatable alloy that is, indeed, heat treated.  For a crankcase it probably won't have lots of silicon (unlike "hypereutectic" aluminum that's used for high-performance pistons in cars and (I'm not sure) AAC, ABC, and AAO model engines.  The heat treating will be done as much to improve machinability as to improve strength, although I'm sure they don't sneer at the extra strength.  (Soft aluminum is a pain to machine -- it's 'gummy', which makes it difficult to achieve a good finish).  Beyond that there's a wide variety of alloys available, and if the engine batches are big enough the manufacturer will even have some latitude to play with the mix themselves if they feel it'll help.

Should I ever go into model engine production, however, I can practically guarantee you that your engine crankcase will be cast out of old lawnmower engines, bent pool-skimmer handles, and broken lawn chair frames.

[proparc]

Exactly the aluminum that's used.

What a wise ass @#$^%$#@

Just joking-that gave me a good laugh.

[Steve Helmick]

I haven't machined any aluminum castings in about 10 years, but did previously. I was somewhat surprised to note that virtually all were alloy #356, even Boeing or other AC companies. There's probably a good reason for that, but you might want to call Henry or Dubby and ask.   Steve

Edit: For pistons, that's a different matter...high silicon, for sure...probably from barstock. From what Tom Knoppi told me, the Soviet engines used up to 22%, and our metalurgists were amazed that they could get that high a mix. This would probably be where you'd use old Vega blocks! I think they're about 14% silicon.

[Alan Hahn]

I remember Glenn Lee telling me to get a chunk of a Chevy Vega crankcase. I don't exactly remember what I was asking him at the time--something about a high silicon aluminum, but for what reason I don't recall!

[proparc]

A356 is your basic aircraft grade casting aluminum. Also pretty standard for engine blocks. A390 is pretty basic for pistons. Of course they sauce it up with various spices to get the unique flavors. Boy, talk about a Freudian slip-been watching too many barbecuing contest shows.  

[Greg L Bahrman]

Due to the thin walls and the different finishes I see I suspect many are pressure cast. High production uses a permanent mold. Making the walls of the finished part all the same thickness simplifies feed-path design. Progressive solidification is easier to maintain in designs with uniform cross sections. It will also make part microstructure and mechanical properties more consistent. Use the proper alloys. There are aluminum alloys tailored for permanent-mold casting including 319, 356, A356, 413, and 535. In general, silicon (Si) is the most important alloying element for any aluminum casting process. Its high specific heat means it holds heat longer than aluminum. During solidification this results in a uniform freezing of the casting ergo a consistent wall thickness and less shrinkage.

[Tim Wescott]

What a wise ass @#$^%$#@

Just joking-that gave me a good laugh.

Well, if you can't dazzle them with brilliance, etc.

[Douglas Ames]

I remember Glenn Lee telling me to get a chunk of a Chevy Vega crankcase. I don't exactly remember what I was asking him at the time--something about a high silicon aluminum, but for what reason I don't recall!

In 2010, good luck finding one. I grew up in Pitt, PA. Vegas rusted out by the third year of ownership and the alum. engines started smoking by the second. The Cosworth Vega was the only high point of that model line. I'd look to all the cast wheels on cars these days, high strength and plentiful.

[Will Davis]

I happen to Like Vegas , This is an old picture of mine in it's prime Sure was a good model airplane hauler in the 70's with the back seat  folded down , Plenty of room for everything ..  ( Charlie Pate.. this is where the chicken incident happened )  .. On availability of Aluminum ,,I agree , probably do better with the high grade alum wheels ..

Will

[Larry Cunningham]

Interesting subject!

A high school friend had a Vega and I thought it was a rotten little car, until I actually drove a Pinto. These were the days when the American auto manufacturers were bent on souring the public on small cars, and slopping the construction of larger cars as well..

But gasoline was cheap and plentiful!

L.

"Why me? Why me all the time?" -Eric Von Zipper (Harvey Lembeck)
"I like you.. And when Eric Von Zipper likes someone, they stay liked."
"We went topsy turvy. When he went topsy, I went turvy.." (paraphrased)

[proparc]

Interesting subject!

Larry, do you you what aluminum they use in a Saito or a PA etc? I know your knowledge base is pretty heavy.

[Tim Wescott]

In 2010, good luck finding one. I grew up in Pitt, PA. Vegas rusted out by the third year of ownership and the alum. engines started smoking by the second. The Cosworth Vega was the only high point of that model line. I'd look to all the cast wheels on cars these days, high strength and plentiful.

Oy, a 'bash Vega' thread.  Should I admit that I have a Vega?  Of course, it's getting an engine swap, which is the only rational thing to do with a Vega.

I think Chevy and Ford surveyed the market and found that the American driving public wanted a good, inexpensive car.  They heard this, and said "Cheap?  They want a cheap car?  We can do that!"

The Chevy Vega, and to a lesser extent the Ford Pinto, are examples of 'cheap' -- as opposed to the Volkswagen bug or the Model A Ford, both of which were inexpensive.  Yes, the bug (and the Model A) has its shortcomings, but you get a _lot_ more bang for your buck with 'inexpensive' than you do with 'cheap'.

[BillLee]

You mean like this?

[Douglas Ames]

I learned to drive on "Astre" in HS Drivers Ed.- A Pontiac Vega. It was a POS then and still is. Sorry.

[Tim Wescott]

You mean like this?

Yup.  Except I don't think those marker lights came from Henry.

[Norm Faith Jr.]

Precipitation Hardening in the First Aerospace Aluminum Alloy: The Wright Flyer Crankcase
Frank W. Gayle 1 and Martha Goodway 2
1 Metallurgy Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. E-mail: fgayle@nist.gov.
2 Conservation Analytical Laboratory, Smithsonian Institution, MRC 534, Washington, DC 20560, USA.



Aluminum has had an essential part in aerospace history from its very inception: An aluminum copper alloy (with a copper composition of 8 percent by weight) was used in the engine that powered the historic first flight of the Wright brothers in 1903. Examination of this alloy shows that it is precipitation-hardened by Guinier-Preston zones in a bimodal distribution, with larger zones (10 to 22 nanometers) originating in the casting practice and finer ones (3 nanometers) resulting from ambient aging over the last 90 years. The precipitation hardening in the Wright Flyer crankcase occurred earlier than the experiments of Wilm in 1909, when such hardening was first discovered, and predates the accepted first aerospace application of precipitation-hardened aluminum in 1910.

Submitted on May 16, 1994
Accepted on September 15, 1994


And still is the "main stay" of aluminum engine manufacturing today. 
Norm

[BillLee]

Yup.  Except I don't think those marker lights came from Henry.

Right. Actually: turn signals to make it a bit safer to drive. Today's standard of driving intelligence wouldn't understand a hand signal.

[Bryan Higgins]

 

[Larry Cunningham]

Larry, do you you what aluminum they use in a Saito or a PA etc? I know your knowledge base is pretty heavy.

You ARE joking, of course? I know virtually nothing about metallurgy.. Well, that is just one of many things I know nothing about! (I *saw* a program on the Discovery channel showing Ferrari casting aluminum V12 engine blocks, does that count?) 

BTW, on the Vega comments, they are only my opinions. The Vega owner loved his car in spite of fit and finish issues; he may still have it. The Pinto owner was a college professor, basically using his car to commute to campus, and had another full sized car (Mercury as I recall) for wife/trip use. My impression of the Pinto was that it was unsafe - brakes were horrible, steering heavy and imprecise, and it was gutless. The body was very rattly and the closing door sounded like it had no rubber gaskets (maybe it didn't). But it was one example of the vehicle, and a well used vanilla trim version to boot.

L.

"Go, and never darken my towels again!" -Groucho Marx

[Larry Cunningham]

Off on the cars tangent (apologies), during college I bought a '60 Austin Healey 3000, which leaked every fluid it had including electricity. It had a cheapo Juarez repaint job, and the first time I washed it, the wand blew a large section of paint off the hood, and later a big chunk of bondo fell out under the headlamp. It had 40-spoke wire wheels which failed. But it did make a lovely sound and was a gorgeous shape! Later the freeze plugs in the block rusted out and I repaired them with JB Weld. Eventually I sold it for $1200 (I had paid $900) and I valued my escape from it. However I saw ((an immaculate example of)) one, same model and color as mine, sold on Barret Jackson the other day for over $100K!

L.

"The best way to have a good idea is to have lots of ideas." -Linus Pauling

[Clancy Arnold]

Am I the only person to successfully overhaul a Vega engine?

I used one trick that most mechanics would not know about.  After removing the Ring Ridge from the top of the cylinders with a Ridge Reamer I chemically etched the cylinder walls with a mixture of circuit board etchant and corn starch.  The corn starch was to thicken the mixture and to hold it on the walls.  Coat a cylinder, wait 5 minutes wash off, recoat wait 5 minutes and clean thoroughly.  Move to the next cylinder.  This method was provided by a friend who was a chemist and in charge of a government plating shop.  The process removed about .0005 inches of aluminum exposing the silicone nodules. 

Did this on a 1974 Vega and drove it for several years after overhaul.  Sold it to an other Vega owner to supply him with a good running engine for his car.  The body or more correctly the drivers door rusted away on mine.  I had it rust proofed when I bought it new but they forgot to do the drivers door.

Do not get me started on Ford Pintos!!!  I had ONE.

Clancy

[Robert Zambelli]

Regarding aluminum, as mentioned, there are many alloys available, tailored to specific purposes.

The best thing to do is pick up a copy of the Marks Mechanical Engineering Handbook and go to the non-ferrous metal section. You should find a listing of the commonly used aluminum alloys as well as the chemical makeup. Lots of good information.

Also, any book on metallurgy would contain all the info you ned.

Bob Z.

[phil c]

Am I the only person to successfully overhaul a Vega engine?

I used one trick that most mechanics would not know about.  After removing the Ring Ridge from the top of the cylinders with a Ridge Reamer I chemically etched the cylinder walls with a mixture of circuit board etchant and corn starch.  The corn starch was to thicken the mixture and to hold it on the walls.  Coat a cylinder, wait 5 minutes wash off, recoat wait 5 minutes and clean thoroughly.  Move to the next cylinder.  This method was provided by a friend who was a chemist and in charge of a government plating shop.  The process removed about .0005 inches of aluminum exposing the silicone nodules. 

GM etched the cylinders when they built the engine.  The pistons were plated with iron to mate with the silicon sleeve.  K&B used the same technology in the Sportster engines.  I'm kinda surprised more engine builders don't use the process.  Maybe the friction is higher than ABC or ABN.

[Tim Wescott]

GM etched the cylinders when they built the engine.  The pistons were plated with iron to mate with the silicon sleeve.  K&B used the same technology in the Sportster engines.  I'm kinda surprised more engine builders don't use the process.  Maybe the friction is higher than ABC or ABN.

Or maybe "uses the same technology as the Chevy Vega!" isn't seen as a strong selling point.

How in heck do you plate iron onto aluminum?

[Pinecone]

The major problem with the Vega engine was that block was not decked.  So when you pulled the head, the tops of the cylinders were not connected to the sides of the block.  So in operation, the tops of the cylinders would move around, causing all sorts of problems.

Some people racing them, would mill the top of the block edges and then cut the head to capture the top of the cylinder.