Theoretical engine material efficiency improvements
 

This morning I was reading on wikipedia about yield and tensile strength of various materials, and it got me to thinking - there are plenty of materials out there which have different properties, which might lead to lighter or more durable or more efficient engines.

Surely most of manufacturing is what it is because of cost and complexity reasons, but I'm curious just what could be produced if cost were less important, or not important at all.

I considered briefly a block sleeved with a titanium alloy. While it likely wouldn't be any stronger than a good steel, titanium weighs less and its thermal conductivity is very significantly lower. In a reciprocating piston engine, is it not the case that the less heat is lost from the cylinder, the more of it can be made useful? Ceramic might be another contender here.

I've read of manufacturers using magnesium to save weight in certain components - e.g. Honda's use of it in transmission cases and oil pans. Reading about its properties leaves me confused, because it appears aluminum is stronger at a given weight, magnesium is just lighter at a given volume. Or, in other words, the same transmission case made out of magnesium would be lighter, but you could make a stronger one with a given weight with aluminum if you were clever with your design.

I'm not sure what properties make for more durable and lower friction bearings, but my guess would be a combination of hardness and Young's modulus.

This is not even getting into the more exotic materials one could make a chassis out of, of course, or things like superconductor wiring.

Polimotor experimented with a plastic 2.0L Ford engine years ago:


https://youtu.be/d3m6snKelAM

https://thekneeslider.com/plastic-en...ne-interested/

and more recently:

https://www.permatex.com/permatex-pa...ngines-future/

When someone says magnesium referring to structural parts ("mag wheels" etc.) they always mean an alloy. The particular alloy is probably stronger and lighter than a more common, lower magnesium, aluminum alloy. Magnesium content is usually between 90% and 98%, aluminum content 1% to 8% But some aluminum alloys are also called magnesium if they are high in magnesium - the alloy Magnalium is 5% magnesium
-mort

Pure magnesium has a nasty tendancy to "burn" furiously once ignited unlike most other metals.

When I was a kid I converted a Microbus from 6v to 12v; the VW 12v flywheel is bigger such that the transmission bell housing on a 6v car needs to be clearanced. I got out the grinder and thought gee, these sparks are HOT. Magnesium.

I believe one of the Japanese manufacturers was working on this back in the 90's. Engine was supposed to be half the size, less than half the weight and a lot more effiecnt(much less heat loss). At the time the ceramics were way to brittle and kept breaking. Maybe the problems were never resolved.

Self-Insulating Ceramics Could Replace Metal in Car Engines
Sudden temperature changes, the classic weakness of ceramics, are no problem for these high-strength materials

From PopSci:

By Jeremy Hsu March 22, 2010


METAL CASTING

New ceramics have the ability to resist sudden temperature changes, just like metals

EPA

Metal alloys have served as the proverbial backbone for car engines and jet turbines alike because of their high strength and ability to resist sudden temperature changes. Now a lighter, cheaper ceramic material that also resists temperature changes may become a viable replacement for expensive metal, according to New Scientist.

Most hot ceramics will fracture and crack if dunked in cold water, because the material contracts too quickly. But the Chinese Academy of Sciences in Beijing has come up with a new family of ceramics that wrap themselves in a buffer layer of insulating air, which protects against the sudden temperature changes.

The new ceramics held their strength even after reaching temperatures of 5,810 degrees F and then being quenched in cold water.

Chinese researchers created the self-insulating ceramic by roughening the surface with plasma etching and acid treatments. The ceramic surface ended up with repeating fin shapes similar to the nanoscale patterns of lotus leaves -- a hydrophobic surface that repels water. The roughened surface also traps pockets of air that become the buffer against sudden temperature change.

On the other hand...
JJ

The real trick isn't using a different material to allow higher efficiency, it is to also be able to produce them at a reasonable cost.

Unless you are doing a theoretical, money is no object exercise.

Valid point

Heh.

If I have my history correct, 25hp VW engine cases were 'aluminum', then the went to 'magnesium' with the 36hp vevision and finally Type IV and aftermarket cases were aluminum again.

What the question reminds me of is that rotary engine seals were either cheap and low-mileage or expensive and lasts-forever. There's an opportunity for a cheap but lasts forever solution.

The other thing is additive manufacturing. Even given the gamut of alloys and plastics, being able to integrate them at the mesoscale at scale means metamaterial alloys with programmable features.

Printing a bronze bushing in a steel bracket is only the beginning. Object with a solid skin and Voronoi cell infill will be superinsulative, and light.