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What is the standard material a combustion chamber is made out of on a standard L4 engine today?
I want to build a new engine from scratch to test both my engineering and mechanical skills but having trouble figure out what materials to use for the combustion chamber. I wouldn't think it would be aluminum, maybe steel?
If you are only talking about the combustion chamber, by far the most used material is aluminum. The combustion chamber is part of the head. It is just the indentation where the valves reside. The combustion chamber affects flame propagation. In the past, besides aluminum, cast iron was used as head material. Cast iron, while being more resilient than aluminum, is harder to work and weighs more. Aluminum also dissipates heat faster than cast iron.
In the picture below, you see the head and two combustion chambers. They are the round indentation in the head. The four round holes in each combustion chamber is where the valves reside. In this case, you have two intake and two exhaust valves. Around the edges of the holes for the valves are valve seats, which are usually made of cast iron, but can be made of other material as well. These are harder and can stand a lot more abuse than can aluminum by itself. In the center of the combustion chamber are the threads for the spark plug.
The most common bore surface is a simple bore in Cast Iron block, Cast Iron sleeve pressed in aluminium block, or Nikasil plated bore in aluminium block.
Other parts of combustion chamber are the top of a piston, which is aluminium, and cylinder head, which can be aluminium or cast iron (don't think it is still in production). The valves - hardened steel or titanium.
For a quick build, as a first engine with no purpose I would build it out of available mild steel and aluminium, using a lathe and a pillar drill :) In fact Lawnmower engine lasts for at least 5 years with no maintenance, and it is 4-stroke, flat head engine with no bearings, no cast iron sleeves, no special materials, no oil pumps, no proper cooling system. Main bearing is just a bore in a block, cam-shaft is a steel shaft with a plastic gear and plastic cams. And it lasts forever! I modified my cam-shaft, I ground off the cams, made steel cams looking like asymmetric washers, put them on the shaft, timed for a racing spec, and welded, and the rest corrected with a file. So my Lawnmower sounds like a racing dirtbike now for last 3 years. And still works!
