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Working 1/25 Engine, out of PLASTIC?


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In the article on Mr. Ryder's Chevelle (now remember NONE of this is plastic), it reads "As the crankshaft turns,the pistons move on firing order, and the camshaft and front pulleys rotate". The heads have 98 parts, 62 holes were drilled into each head, it has working valve spring assemblies with spring,keeper,& rocker arms.As the engine turns over you can see the camshaft lobs through the lifter holes, it is one fantastic build!

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Wouldn't almost any fuel do some sort of damage to plastic, even un-ignited???

R&D did a crankshaft, rods & pistons, if you can find them. I played around with trying to fit one of those into that spare block that came with the pro street Nova a few years ago.

As for the plastic crank & cam shafts, look for the blueprinter parts pack issue.

Fujimi also has their enthusiast series kits that have what appear to be accurate crank, rod & piston detail Anyone know if they actually rotate?

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In the article on Mr. Ryder's Chevelle (now remember NONE of this is plastic), it reads "As the crankshaft turns,the pistons move on firing order, and the camshaft and front pulleys rotate". The heads have 98 parts, 62 holes were drilled into each head, it has working valve spring assemblies with spring,keeper,& rocker arms.As the engine turns over you can see the camshaft lobs through the lifter holes, it is one fantastic build!

Where the heck is this article ? I'd love to read it

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I was looking at building a small V12 based roughly off Ferrari specs.

And for a number of reasons about the smallest I could go is 1/10th and that would be pushing the very limits of a lot of things. The biggest compromise is the spark plugs, which they make some tiny plugs, Viper makes a 10-40 plug. However, even that plug is way out of scale for 1/12th and it made for some issues in the head with placement and valve clearence so I had to scale it up. There were some other things that were just hard to find and hard to fab for anything too much smaller like helix cut gears for timing, piston rings... just stuff that would be very difficult to make, not so much machining the parts but then you have heat treatments and special coatings on top of that.

In any event, I have cad drawings about 90% completed for a very small V12.

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The problem I see aside from the obvious combustion melting the engine down the first turn over and the size of the parts is it running right if at all. I seem to remember an article about a dude making a larger scale Ferrari ... that actually ran ( he had lots of cash ) Seems I remember that it idled fine but after a certain RPM it didn't wanna go right certain things moved too fast for it to do so. That being said we are talking way smaller than he did his in so I don't even see it being able to idle at all. I'd also have to say if it was possible to make a running engine out of the plastic we use .... why are there no actual Running Visable V8s ??

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Like Mark (Scale-Master) said, the atmosphere would be a major problem. You can only "atomize" the air/fuel mixture so much... The little particles of fuel would probably be larger than the gap between the electrode and bridge on the plugs, and it just wouldn't be able to ignite the mixture to put it simply.

Also, Harry is right about the tolerances, parts, materials, etc... I'd be willing to bet that it would cost a million bucks or more to do!

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I agree with the statements that normal physics would prevent a fully detailed plastic engine from actually running on fuel, but it sure would be cool to see someone build a 1/25 engine with moving parts like a 1/8 Pocher. In fact, it would be cool to see someone build a 1/25 model with all the different mechanical parts of a Pocher. (And make it work better.) I'm looking forward to it, and I hope I live long enough to see such a thing. Someone with the skills and tools of a fine watchmaker could possibly do it.

Edited by sjordan2
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Take a piece of scrap plastic, say, a small length of sprue. About the size of a scale piston & rod. Now drop that into a small container of whatever you imagine as the fuel you would use.

Now quote the Wicked Witch of the West....

"MELTING! I'M MELTING!"

That is what would happen, somewhere inside the block or heads.

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The problem I see aside from the obvious combustion melting the engine down the first turn over and the size of the parts is it running right if at all. I seem to remember an article about a dude making a larger scale Ferrari ... that actually ran ( he had lots of cash ) Seems I remember that it idled fine but after a certain RPM it didn't wanna go right certain things moved too fast for it to do so. That being said we are talking way smaller than he did his in so I don't even see it being able to idle at all. I'd also have to say if it was possible to make a running engine out of the plastic we use .... why are there no actual Running Visable V8s ??

Pierre Scerri's 1/3 Ferrari 312

He didn't have a lot of money, just a well equipt shop and 20,000 spare hours.... or about 15 years.

Edited by CAL
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LOL, this brings back memories!!!! A good while back, I think I was about fifteen or so. I was impressed by the detail of an engine block that came in a kit. It had the detail of the piston tops in the cylinders and the lifter hole detail in the valley. I started thinking of how cool it would be to have a 1/25 "working" engine. When I say working, I just mean that the crank could be turned by hand to see the pistons move. So.... I built a crank by using sheet plastic for the counter weights and plastic rod for the journals. I then made the connecting rods by taking short lengths of brass wire and making a "loop" at each end. The pistons were small plastic tube pieces with sheet styrene for the "domes". A small piece of wire was pushed through the sides of the pistons for the "Wrist pins". I then super glued small lengths of aluminum tubing into the block after drilling each cylinder. A flywheel was cut out of sheet plastic. When it was finished, you could take the crank snout and turn it to see the pistons move. It didn't last long though before the journals broke away from the counter weights! LOL

It was cool while it lasted though!

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Pierre Scerri's 1/3 Ferrari 312

He didn't have a lot of money, just a well equipt shop and 20,000 spare hours.... or about 15 years.

That thing was AWESOME!!

IIRC, he wanted to sell it, or did sell it, because he was planning to build another one (a different Ferrari). I could be wrong, though... been a while since I saw it.

Definitely worth looking up if you've never seen it though. It was VERY, VERY cool!

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It is kind of hard to get past the fact that styrene melts at 212 degrees and the exhust temp of a gas engine is somewhere in the neighborhood of 1300 degrees, just the minimum combustion temp of gasoline is 495 F. The oil temp at the ring can reach 320 F.

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