Aluminum engines

[Guest]

I am finding that aluminum engines have been around for many years, in both automotive and aircraft applications. My early impression of aluminum engines came from the early Chevy Vega, which seemed to have a poor reputation. One explanation was that the block was aluminum, but the heads were steels, so the two metals expanded and contracted at different rates. However, I understand that many current production vehicles use this arrangement successfully. Another explanation that I heard was that the problem was fixed when steel cylinder sleeves were put in the aluminum block. Will the current trend continue, until all blocks are aluminum?

[Guest BruceW]

I'm not sure when the first aluminum engines were used in automobiles, but the early 1930 Franklins had a a cast aluminum, in-line six cylinder engine that was air cooled. It is said that each cylinder could be removed individually from the engine.

[Guest Albert]

The early Vega used and all al. block with a coating on the inside of the cyl wall, but once the coating wore off or if the engine overheated once that was the beginning of the end. a lot of engines where board oversize and steel sleeved on those motors. Some of the cady's are al blocks (steel sleeved) with cast iron heads, and most other cars are now cast iron blocks and al heads, every things works good as long as you change your coolent every 4 years or else the coolent will eat under the al head or block (blown head gasket) and the manufacture has not used under size head bolts or not enough, ie Neons where they now use a multi layer all steel head gasket with a sealent as a replacement.

[Guest]

When I say modular I mean the block is assembled of individual component parts. For example, an engine has heads, cylinders, bottom end all in separate pieces and their strength is derived from the complete assy with one piece being just a holder of all the studs.<P>Opposed Continental aircraft engines are a good example, the actual engine case is just a shell that everything bolts to. Here's a picture, <A HREF="http://www.prime-mover.org/Engines/Images/conttsiol550.jpg" TARGET=_blank>http://www.prime-mover.org/Engines/Images/conttsiol550.jpg</A> <BR>I think the manufacturers must start to think about horsepower per pound instead of horsepower per cubic inch. Have you seen some of the weights of the new vehicles lately, I don't know how they make plastic weigh so much. Must be all the cupholders!

[ronbarn]

The first known use of aluminum for an engine goes back to 1895. Marmon not only used a lot of aluminum in the engines going back to the teens, but also had cast aluminum bodies circe 1912. His crowning glory was the 1931-1933 sixteen cylinder engines with steel cylinders pressed in the aluminum block. The total engine weighed just 930 pound and generated 200 HP - not bad for sixteen cylinders.

[Guest]

many newer designs use "cast-in" cylinder linings where the composition of the bore sides is different from the block, although both are alloy. The Vega engine was about the worst Al-iron combination I've seen - it's not indicative of the capability. The coolants are not a corrosion issue anymore - they are formulated for Al. The drawback is cost - Al costs more than Iron, but otherwise offers all the advantages of "adding lightness.".

[Guest]

Since the beginning of the industry it has been pretty much standard to make the crankcases of composite{i.e. separate cylinder block} engines from some sort of aluminum alloy, generally with silicon.

[Guest]

Oh boy, do I hate those cast iron heads on AL blocks. No matter what you do it seems they are doomed to head gasket failure especially if you stress them severly. I have good luck with AL heads on Al blocks with copper o-rings for gaskets with cast bore sleeves. You have to use larger wire with every head pull because of the brinelling problem in aluminum, but it sure holds high compression well. <P>Maybe one day all the manufacturers will do it that way as the heat transfer through a solid copper wire sure beats a composition gasket. The modular design of other aluminum engines like outboards are another good idea that allows through case studs to do the clamping instead of distortion causing threaded fasteners in the block. I once made torque plates for a small block chevy and had the opportunity to see the bore size change that occurs under bolt torque. The engine had just been honed to size and I put the torque plate on and measured the bores. <P>Every bore became pentagon shaped at the top 2 inches of bore because of the 5 bolt design. The sizes changed by about 0.0005" under the torque of regular bolts and about half that with studs, scary any way you look at it. Aluminum is even worse, I wouldn't even think about boring/honing an aluminum engine now without torque plates. The modular design gets rid of the bolts in the cylinders and is the best way to go. Oh well you can always wish.

[Guest]

Please explain modular design. How are the heads attached, if not by bolts into the block?

[Guest]

Another car that people don't talk about in conjunction with aluminum engines is the early '60s Rambler. It had an alumimun engine which held up faily well. I don't remember if they had cast iron heads or aluminum heads. AMC called the car the Rambler Classic.<BR>Roger

[Guest BruceW]

The cylinder heads on the aluminum AMC Rambler engines of the early 1960s were cast iron.

[Guest De Soto Frank]

Interesting post;<P>Didn't notice any remarks about the "iron block - aluminum head" combination, the "high-perfromance heads of the '30's & '40s.