Plastic engines

[gone-ot]

Originally Posted by Frank Lee

The point is...

...plastic CARS to go along with our plastic MONEY and plastic SOCIETY!

[Christ]

Originally Posted by Old Tele man

...plastic CARS to go along with our plastic MONEY and plastic SOCIETY!

Saturn.

[shovel]

Originally Posted by Old Tele man

...plastic CARS to go along with our plastic MONEY and plastic SOCIETY!

Plastic people in their plastic cars eat plastic food from plastic jars

you know what else is plastic? flesh, hair and fingernails! chances are overwhelmingly high that your computer is too! and the packaging that keeps your food fresh! and the pipes that deliver your water & haul your chocolate away!

man plastic sure sucks doesn't it?

[Frank Lee]

Originally Posted by Christ

Requires much less machine time, that's for sure. Even the most dense composites can be cut with carbide tools in a very short time compared to steel. Aluminum is better, but still not as fast.

The bits that need machining are still metal.

[Christ]

Originally Posted by Frank Lee

The bits that need machining are still metal.

Plastic casting is more efficient when someone/something is trimming flash and overcast, rather than trying to tune the process to prevent it from happening. Often, gates and flash are now trimmed/removed mechanically. No need for human input. Isn't that great?

[shovel]

Originally Posted by Frank Lee

The bits that need machining are still metal.

Forgive me if I'm retarded here, but a typical engine block is effectively a 2-layer affair, with cylinders that hold the explosions in and a shell that holds the oil and water in, around the outside of the cylinders. that shell has no compelling reason to be cast+machined out of metal does it?

[Christ]

Originally Posted by shovel

Forgive me if I'm retarded here, but a typical engine block is effectively a 2-layer affair, with cylinders that hold the explosions in and a shell that holds the oil and water in, around the outside of the cylinders. that shell has no compelling reason to be cast+machined out of metal does it?

You're not retarded, first off.

Secondly, engines now are typically made as you describe, with sleeves. The block actually has coolant passages and such machined into it.

Even with a plastic block, there will be metal parts that need to be machined, though. There have to be sealing surfaces and the like, and those have to be milled to specific tolerances in order to create a positive seal. Bearings, as well, have to be post-machined after casting to ensure a proper dimension and that conditions are ideal for use as an engine.

[discovery]

i think they had this idea back in the '90 even in the '80 i saw a picture.

[rmay635703]

My high school had a clear glass ethanol motor for the energy and transportation classes.

I got to play with it maybe 5 minutes It had no throttle but did have A/F ratio & timing/spark. I also believe you could adjust the compression ratio.

Interesting to watch and if you could turn the timing just right you could make it reverse.

You could watch and monitor the RPM, fuel flow rate and you could also put a load on the motor and again monitor RPM, fuel flow rate and test different timings and A/Fs the whole while.

I really wish I could have taken that home.

[Otto]

Originally Posted by shovel

Forgive me if I'm retarded here, but a typical engine block is effectively a 2-layer affair, with cylinders that hold the explosions in and a shell that holds the oil and water in, around the outside of the cylinders. that shell has no compelling reason to be cast+machined out of metal does it?

That is essentially correct.

However, there will be thermal compatibility issues with plastic, perhaps even moreso than with the various metals now used in car engines.

Ultimately, comparative costs will drive the issue, unless you have a DoD or NASA budget at your disposal.

The automotive engineering department at Western Washington University built a small engine out of carbon fiber some years back. Worked, and was pretty light, but I don't know about comparative cost and reliability.