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Christ 01-25-2010 01:35 PM

Plastic engines
 
I searched for it, but I didn't find anything here, and while checking out some of the archives at The Knee Slider, I found an article about plastic engines possibly being a viable alternative for automobile/motorcycle engines of current production types.

Article follows:

Plastic Engines – We Have the Technology – Is Anyone Interested?

http://thekneeslider.com/images/2009...gine-block.jpg

Christ 01-25-2010 01:41 PM

First comment -

From the looks, that block is just that - a block. It would seem that the primary friction/heat parts of the block will not be replaced, and this is discussed in the article.

It seems like, if we can assume anything from that image, the bearing surfaces and piston sleeves will be part of a secondary "bed plate" that is either fastened/adhered to the plastic block "casing" (if you will).

If I might add another point of discussion to this: What about the availability of self-lubricating plastics? Would they be viable for use in low-speed engine applications (Sub-1000 RPM max) where low heat and power generation are required?

What about applications for air-engines? How about plastic parts for the parts of electric motors that aren't required to be metal by design?

What exactly are the possibilities of manufactured plastic components?

gone-ot 01-25-2010 01:46 PM

...I remember reading that article. At the time, I had a '72 Pinto with that Ford-of-Britain (FOB) 1.6L engine...got 36 mpg at typical 55 mph, of course, I'd done a few tweeks like change the stock 3.55:1 axle to 3.18:1; switch from breaker points to fully electronic ignition; and installed a "tri-Y" header from a Cortina.

shovel 01-25-2010 04:05 PM

a while back I got the notion that molded plastic vane-type stirling engines (with flexible vanes) could be built into the wheels of cars and replaced/recycled after 10,000 miles or whenever their performance begins to suffer.

but then i remembered that i'm not in charge of jack squat and even if i had the cure for cancer written on a napkin i wouldn't have a clue how to start a business making it.

Peter7307 01-25-2010 04:47 PM

Carbon fibre can be engineered to take the stresses involved and ceramic coatings can deal with the heat and bedplates etc to take the bearings will handle that.

I suggest it is more a case of what will it cost , rather than can it be made to work.

Even those very familiar with the technology (Ferrari for example) have yet to implement it beyond the cosmetic applications.

Pete.

Frank Lee 01-25-2010 05:29 PM

Tough to beat plain ol ancient cast iron for cylinders. Hasn't been done yet that I'm aware of.

luvit 01-25-2010 05:30 PM

my accord has a pizza box under the hood. with hho.

Christ 01-25-2010 06:23 PM

Quote:

Originally Posted by Frank Lee (Post 156685)
Tough to beat plain ol ancient cast iron for cylinders. Hasn't been done yet that I'm aware of.

Did you read the second post? They're using the composite for a block casing, then adding in sleeves and a bed pan for the bearings/pistons. The base castings are plastic, but there's still iron in the block. They're claiming a weight savings up to 20-30% over aluminum engines, though. Significant.

gone-ot 01-25-2010 06:42 PM

...ie: a "plastic" spider holding "cast iron" sleaves and bearings in their proper locations.

Frank Lee 01-25-2010 07:54 PM

Yes I did read it. Just sayin.

Christ 01-25-2010 07:58 PM

Quote:

Originally Posted by Frank Lee (Post 156732)
Yes I did read it. Just sayin.

Okie, I was just making sure you didn't miss it, as it's a crucial piece of the story.

Frank Lee 01-25-2010 11:54 PM

It was re: attempts to make alum cyls work i.e. with nikacyl (sp?) and whatnot. They sorta work, but try to bore/hone/do anything with them. Not user friendly like iron.

Christ 01-25-2010 11:55 PM

Quote:

Originally Posted by Frank Lee (Post 156782)
It was re: attempts to make alum cyls work i.e. with nikacyl (sp?) and whatnot. They sorta work, but try to bore/hone/do anything with them. Not user friendly like iron.

Gotcha. Check your PM's.

CoastRider 01-26-2010 10:16 AM

I hate plastic! I like things that are made to last, and/or servicable. Plastic just gets thrown away when it no longer serves it's purpose.

gone-ot 01-26-2010 10:51 AM

Quote:

Originally Posted by CoastRider (Post 156855)
I hate plastic! I like things that are made to last, and/or servicable. Plastic just gets thrown away when it no longer serves it's purpose.

...but that's exactly the mantra of today's society, ie: "throw away" rather than repair!

...yesterday, R&R meant remove & repair; but, today it means remove & replace.

Peter7307 01-26-2010 05:01 PM

Quote:

Originally Posted by Frank Lee (Post 156782)
It was re: attempts to make alum cyls work i.e. with nikacyl (sp?) and whatnot. They sorta work, but try to bore/hone/do anything with them. Not user friendly like iron.

Frank , agreed. User friendly they are not.

I think it is like a lot of stuff these days.
When it works it works well and is reliable but when it fails it is not repairable and has to be replaced.

Many cars have that now with fuel pumps.
When they fail they are replaced and there are not "user serviceable part inside" as the warning label suggests.

The costs of labour also plays a part here too.
When it is cheaper to throw it away and buy a new one than to spend time tracking the fault and repairing it then that is exactly what happens.

The other side is "mechanics" now can't trace faults or repair things simply because no one is there to tell them how it is done and most people won't pay someone to do it anyway.

Pete.

Frank Lee 01-26-2010 05:16 PM

You are spot-on, Pete. I remember when mechanical fuel pumps were disassemble-able. When the diaphragm went bad, you could pull it out and replace it. Only it.

I can deluge y'all with stories about people who had their vehicles- or even other stuff- in to the shop for repairs, and it remained broken even after the "mechanics" threw hundreds of dollars worth of new parts at it.

Evidently diagnostic skills are a thing of the past. :mad:

XGF's mom had a poor running carbd car. It had the fuel economy of a bus, no power, etc. The local garage threw everything at it- computer, wires... basically replaced the entire ignition system from top to bottom... can you imagine the cost???... and IIRC some fuel system parts too, with no improvement. I said "lemme have a looky-see". Brought it to my place, popped the lid off the carb- didn't even remove the body- pulled the floats out and threw em in a bucket of water. One of them went straight for the bottom. DAH. $4.60 later she had her car back, running better than it had in years.

That's basic stuff Man. BASIC. :rolleyes:

bgd73 01-26-2010 06:27 PM

interesting.

The epiphany...

if an engine were designed compact enough into self balance, (as if I haven't babbled a 3 main boxer enough), the components would have to remain metal.

Kinda funny.

The plastic proves how stupid the inline is...

Christ 01-26-2010 07:32 PM

Quote:

Originally Posted by bgd73 (Post 156962)
interesting.

The epiphany...

if an engine were designed compact enough into self balance, (as if I haven't babbled a 3 main boxer enough), the components would have to remain metal.

Kinda funny.

The plastic proves how stupid the inline is...

Interesting point of view... considering that the idea has also been considered for rotaries, and, indeed, boxer engines.

smflorkey 01-26-2010 08:31 PM

Quote:

Originally Posted by CoastRider (Post 156855)
I hate plastic! I like things that are made to last, and/or servicable. Plastic just gets thrown away when it no longer serves it's purpose.

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. :mad:

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. ;)

gone-ot 01-26-2010 08:36 PM

...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 01-26-2010 08:44 PM

Quote:

Originally Posted by smflorkey (Post 157004)
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. :mad:

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 01-26-2010 08:45 PM

Quote:

Originally Posted by Old Tele man (Post 157005)
...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 01-26-2010 09:29 PM

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

Christ 01-26-2010 09:39 PM

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 01-26-2010 09:43 PM

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

CoastRider 01-27-2010 08:05 AM

Quote:

Originally Posted by Christ (Post 157012)
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 01-27-2010 09:34 AM

Quote:

Originally Posted by CoastRider (Post 157095)
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 01-27-2010 12:29 PM

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 01-27-2010 01:01 PM

Quote:

Originally Posted by TheEnemy (Post 157136)
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.

TheEnemy 01-27-2010 01:12 PM

I am not aware of any plastic that doesn't deform under stress. Also, I mentioned that

Quote:

unless it has a metal structure that is then covered in plastic that the head, and bearings bolt to,
Which I can't tell if they did or not.

I don't know if carbon fiber has the same issues with stretching as plastics, but if it doesn't then that would be a truly light, if not expensive as heck engine.

Christ 01-27-2010 01:17 PM

Truly expensive.

From what I've been able to glean through limited reading and images, I don't see that there is a structure that is molded into the plastic, but it appears that there are two structures on the block, a bedplate for the crank which also has the sleeves, and a cap which installs on the block deck, then a matching cap which installs on the lower deck surface of the head, so that when the head bolts are installed, everything (including the composite block) is compressed together.

I have decided through thought exercises that a potentially better design would be to have a bedplate for the crank bearings, with only a small portion of the sleeves attached, and a groove into which the upper deck plate (which now contains the majority of the sleeves) fits. There are two good designs which could be used to mate the upper and lower portions of the sleeves, namely stress fracking, which creates uneven, but uniform mating surfaces, but is potentially timely and not always predictable, and groove/insert, in which one sleeve's ID is widened while the other portion's OD is reduced so that they interference fit together.

The reason I feel this to be superior to what I've seen is that the piston's travel never reaches a certain portion of the cylinder, and that portion of the cylinder is where the two portions of the sleeves could be mated. The sleeves having to mate each piece of the upper and lower plates prevents the plastic from being strained, and ensures that stresses are somewhat evenly distributed between upper and lower deck surfaces.

TheEnemy 01-27-2010 01:57 PM

I was figurin that the head (metal) would bolt to the cylenders, and the main bearings would also bolt to the cylenders. The plastic portions would hold the oil and coolant in where its needed.

One thing to note it that the engine pictured was an expereimental race engine, if it lasts through the race thats good enough for them. What I find interesting though is it wasn't a plastic part that failed.

Christ 01-27-2010 02:36 PM

Quote:

Originally Posted by TheEnemy (Post 157159)
I was figurin that the head (metal) would bolt to the cylenders, and the main bearings would also bolt to the cylenders. The plastic portions would hold the oil and coolant in where its needed.

One thing to note it that the engine pictured was an expereimental race engine, if it lasts through the race thats good enough for them. What I find interesting though is it wasn't a plastic part that failed.

Wouldn't that be the way, though... :rolleyes: LOL.

My suggestion comes from casting the cylinder heads in plastic, also, and bonding that plastic to the metal "caps" which form the combustion chambers in the cylinder head.

Of course, I have no clue who to send a suggestion like that to.

Christ 01-27-2010 02:42 PM

I also suggest that for a DIY'er, plastic is probably a more viable option to prototype engine parts than most metals, and can be had in larger quantity by digging through your neighbors' trash! LOL.

Considering that grocery bags get thrown away in the thousands every day in many communities, and they melt easily in olive oil at ~240* (as opposed to 1000+ for metals), and reform into a very dense plastic, which can then be chemically plated or coated with high-temp ceramics, etc... all things that a DIY prototype engineer could achieve in his home "lab".

Christ 01-27-2010 02:50 PM

I also still question the viability of self-lubricating plastics such as Nylon or Delrin for use in very slow-speed engines.

shovel 01-27-2010 03:20 PM

I really don't see what the difficulty is.... you make the actual "engine" (cylinder sleeves, head, valvetrain, crank, and a little webbing to hold them together) out of metal as usual and then wrap the whole thing in a cast plastic jacket with lubricant/coolant channels. Sounds pretty simple to me.

Frank Lee 01-27-2010 05:58 PM

The point is... :confused:

shovel 01-27-2010 06:38 PM

Quote:

Originally Posted by Frank Lee (Post 157212)
The point is... :confused:

plastic weighs less, costs less, and potentially requires less machine time than steel?

this is, after all, the age in which Mazda re-engineered their rear view mirror to save 15 grams. :thumbup:

Christ 01-27-2010 06:41 PM

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.


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