Miniature V10 engine

Originally published at: https://boingboing.net/2017/08/31/miniature-v10-engine.html

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I guess 1/3 is the linear scale, which means that the original engine (if proportions remained the same) had 27 times the displacement, i.e. 3,375 liters (206 cubic inches for the metric challenged)

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People with this much talent really piss me off.

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I’ve never even heard of a V10. Is this a thing?

You’re correct, because Cory, but I still have to say, on first read… I was imagining a train engine.

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Install that into a coffee cup, and you have a buyer.

Yep - think Lamborghini or other fast-mover manufacturers.
(And some pickup trucks, strangely enough.)

If you want weird, look at things like the Napier Deltic…

Why didn’t I just look under the hood of one of my Lamborghinis?

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Oh yeah. Lambo, Ford, Audi, BMW, Dodge, Ford, Lexus, Porsche, and VW have all produced V10 powerplants.

Did any see any dyno numbers on that 125cc 10? Usually we see singles at that size so I’m curious to see what a 10 can do at that displacement. Obviously the torque you get from a thumper isn’t getting matched by a 10 but the RPM limit and horsepower could be interesting.

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IC engines are interesting because the power scales in a complicated way. Even a lot of petrolheads don’t actually understand it. Yet the theory was well known by the 1900s.*
The power that can be developed by a piston engine is limited by the area of the piston crown, the peak allowable pressure, and the maximum rubbing velocity of the rings on the cylinder wall. That’s it.
If you scale an engine down by 3 times, the crown area is 1/9. But the maximum allowable rubbing speed is roughly the same, which means that the engine can turn over at 3 times the rpm. Thus in theory it can deliver 1/9 the power of the large engine, not 1/27. This goes some way to explain why engines are getting smaller; higher pressures are possible these days with better head and crown design, even with gasoline, engines are reliable at higher rpm. As a result the necessary power can be developed by smaller, lighter engines which are more thermally efficient. There are 1 litre engines now which develop the same power as an old 5litre plus hemi, with twice the thermal efficiency and much longer life between overhauls.

All of which goes to say that tiny engines like this one, of around 125cc displacement, can deliver rather a lot of power. However, model engines rarely meet the tolerances and materials requirements of modern production engines, so are unlikely to be very reliable or thermally efficient.

*Because everybody was using basically the same materials and fuel, the UK government of the time taxed vehicles on total piston crown area, not capacity.

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Lots of them in the marine world. To make big Diesels basically start out with in-line or V and then keep adding cylinders. I think they currently go up to V14 or even V18.

Edit - Wärtsilä currently goes up to V20, but their biggest engine is a straight-14 (you need a big ship as it needs over 14M headroom and is a crosshead design.)

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but…why?

Because.

I mean, I’d never spend my time on such a project, but you have to admire it, just because.

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I can admire the craftsmanship and effort and skill; but also ask…WHY?!

Just because it can be done, doesn’t mean I can understand why you’d do it.

Impressive to see a functioning model at that scale. I’m curious to know why the belt driven valve train instead of traditional rods.

Is that a typical v10 design for timing or is it just because of the scale involved means functional rods are too difficult?

Dual overhead cams is way better than an undershot camshaft driving connecting rods. You have more options for valve placement and you can have more valves, leading to more efficiency and power for the same cylinder displacement. And no pesky hydro lifters needed, you can get rid of bucket-style cam followers entirely and just use rollers instead.

Of course at this point camshafts and cam followers are crusty old tech, valves in my daily driver are completely solenoid driven and computer controlled so that I have even more options than I would with multiple overhead cams.

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Actual overhead camshafts have been in general use for quite some time outside the technology backwaters of the US automotive industry.

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Well, it’s true that we’ve only had them since 1903, whereas the British have had them since 1902. Clearly we are stone age primitives over here.

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Well, quite, my dear fellow. Quite.

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Why do anything? I like to play guitar and own 3 of them, but I’ll never do anything other than make bad music by myself or look stupid with my friends that can actually play like professionals.

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