Plastic engines

[gone-ot]

...well, hold onto your fears because DARPA and NASA are looking into ceramic jet engine turbines held within plastic (carbon-fiber) outer housings...super, SUPER lightweight and capable of producing 'near' after-burning power levels during a finite (ie: "oneway") lifetime/flight duration.

[Christ]

Originally Posted by smflorkey

Yes, plastic does not last. I have had two Hondas blow chunks out of the top radiator tanks -- PLASTIC radiator tanks! The only thing the mechanic can do is replace the whole radiator.

I understand the radiator core is aluminum to save weight and money. Brass and copper are much heavier and more expensive. But aluminum is much harder to solder, even with the right materials, so the most cost effective thing is to put plastic tanks on the ends of these aluminum cores. They're light and relatively inexpensive, but I'm almost to the point of just replacing Honda radiators every ten years so I don't find myself driving a green cloud down the highway.

And they want me to trust a plastic engine block? Even with iron cylinder sleeves and crank/cam supports, I don't trust the plastic to keep the iron together very long. I won't buy one if anything else is available. YMMV.

That's not true at all. The mechanic is only replacing the core entirely because he either doesn't know how/where to get the end tanks, or doesn't know how to replace them. This is quite common. In fact, 80% of "throw away" parts are still repairable. I do it alot.

[Christ]

Originally Posted by Old Tele man

...well, hold onto your fears because DARPA and NASA are looking into ceramic jet engine turbines held within plastic (carbon-fiber) outer housings...super, SUPER lightweight and capable of producing 'near' after-burning power levels during a finite (ie: "oneway") lifetime/flight duration.

Plastic isn't carbon fiber, that I know of... if they're using carbon fiber, there's a good (light weight/super strong/resilient) reason for it.

[gone-ot]

...isn't carbon-fiber bonded using epoxy which is generically a variant of plastic?

[Christ]

Polyester, but the resin is for bonding and hardening, the CF is actually the strength of the part.

I see what you suggest, though.

[gone-ot]

...as Mr. Robinson confided to Benjamin in "The Graduate": "...plastic!"

[CoastRider]

Originally Posted by Christ

That's not true at all. The mechanic is only replacing the core entirely because he either doesn't know how/where to get the end tanks, or doesn't know how to replace them. This is quite common. In fact, 80% of "throw away" parts are still repairable. I do it alot.

I have looked into replacing the side tanks but usually the rad core is kinda crusty, not to mention I dont trust recrimping the tiny tabs that hold the tanks on.

[Christ]

Originally Posted by CoastRider

I have looked into replacing the side tanks but usually the rad core is kinda crusty, not to mention I dont trust recrimping the tiny tabs that hold the tanks on.

When you replace the end tanks, those tabs do nothing but hold it in place, they don't seal it. Once the sealant cures, they're not even necessary. I use ratchet straps to tighten them down, but I'm not sure what kind of "glue" I have.

[TheEnemy]

From what I remember from a materials class I took (10 years ago now so I might have the terms a bit mixed up)

Most materials have a fatique limit, if you stay below that amount of force there is no permanent deformation of the material. Plastic doesn't have that limit, which means any force applied causes at least some deformation.

Now with the plastic engine block, unless it has a metal structure that is then covered in plastic that the head, and bearings bolt to, the crank will slowly over time stretch down away from the head. The engine will slowly loose its compression ratio, and will start dumping oil out of the front and rear main seals as they will become ovals instead of circles.

Truly a throw away design.

[Christ]

Originally Posted by TheEnemy

From what I remember from a materials class I took (10 years ago now so I might have the terms a bit mixed up)

Most materials have a fatique limit, if you stay below that amount of force there is no permanent deformation of the material. Plastic doesn't have that limit, which means any force applied causes at least some deformation.

Now with the plastic engine block, unless it has a metal structure that is then covered in plastic that the head, and bearings bolt to, the crank will slowly over time stretch down away from the head. The engine will slowly loose its compression ratio, and will start dumping oil out of the front and rear main seals as they will become ovals instead of circles.

Truly a throw away design.

Imagine for a second that plastic doesn't necessarily mean the stuff your soda bottles are made of...

Plastic means any materials which contains properties which are plastic-like. They're using composites in the design because the composites are/can be made close to the strength of some metals with minimum stress warpage (into the thousandths of an inch per Nth force).

I'm not reading too far into it, because unless I cast one myself, I'll likely never see them, but it's still a rather interesting concept, just like compressed graphite, which also "would never work" before it was implemented, and eventually did work.