7 ms·
Internal Combustion Engine (2021)
- bell-cot 3mo ago[2021] Originally 2333 points and 392 comments: https://news.ycombinator.com/item?id=26991300 https://news.ycombinator.com/item?id=26991300
- felooboolooomba 3mo agoPro tip: Show a message if WebGL is disabled instead of a blank space.
- mrhottakes 3mo agoExcellent animations.
- misiek08 3mo agoYou meant - awful knocking combustion in the first, main animation? I never catches any real bug is those great posts, but this one, especially as first animation on the page - weird.
- Toutouxc 3mo agoYou might be misreading the animation. It's a direct injection engine, the thing that happens during the compression stroke is fuel injection. Ignition happens a few degrees before TDC, which is realistic.
- deleted 3mo ago[deleted]
- lostlogin 3mo agoOne of the rare situations where someone wants a bit of retard?
- HoldOnAMinute 3mo agoThat is often more advisable as opposed to doing it fully.
- zuzululu 3mo ago[flagged]
- throw567643u8 3mo agoProbably better for the environment too.
- rootusrootus 3mo agoNo
- Sohcahtoa82 3mo agoThe carbon footprint of producing an EV is higher than an ICE. Nobody disputes that. But the lower carbon footprint of operating the an EV makes the EV have a lower footprint over the life of the vehicle. This is true even if your electricity comes purely from coal, as a coal power plant gets an economy of scale that an ICE doesn't achieve. If your power comes from a renewable source, then the trade-off happens even sooner.
- zuzululu 3mo agothe problem is where these lithiums are sourced from and that raises the costs of human rights
- Sohcahtoa82 3mo agoQuestioning the lithium source is valid, but also a red herring when we're talking about environmental impact. But yes, battery minerals can involve human rights abuses. But ICE vehicles are also built from steel, aluminum, copper, rubber, electronics, and metals that can involve forced labor, unsafe mining, land displacement, pollution, or exploitative labor. The ethical issue is supply chain due diligence across the whole auto industry, not just lithium. Funny how some people (Mostly anti-EV folks) only discover supply chain ethics only when the car has a battery.
- bob1029 3mo ago> Presence of oil is critical here as it creates conditions for hydrodynamic lubrication. You can hear this effect in some vehicles at initial startup time for a few seconds. I know of certain Ford engines where it actually causes issues over time. The model years with auto start/stop have the worst of the cam rattle disease.
- Toutouxc 3mo agoNote that that sentence is talking about the crankshaft bearings and their hydrodynamic lubrication, which is, well, elsewhere and separate from any cam rattle issues (including the cam phaser oil starvation that you might be referring to).
- culopatin 3mo agoLifters also often drain while sitting and valve lash is greater at start until they get slapped a few times
- LeifCarrotson 3mo agoAuto start/stop isn't off for enough time for the oil to drain from the galleries and especially not out of the bearing journals. It's the first few seconds after an engine has been off for hours (or worse, for potentially years) that are the problem.
- toxik 3mo agoI thought it pretty well established that auto on/off is bad for the engine, as is intermittently turning off some cylinders as some do. Is that wrong?
- vel0city 3mo agoIt sounds like you're talking more about systems that supposedly disengage some cylinders while the car is cruising. Some engines with that kind of technology have been known to damage cylinders for multitude of reasons. That's very different from the start/stop feature they're talking about. That's about fully stopping the engine when you come to a complete stop like at a red light and then automatically starting again when you get off the brake.
- fauria 3mo ago"in real running engines the rotating crankshaft should float completely on a very thin surface of oil" - I found this to be a great insight.
- arlattimore 3mo agoThe bearing surfaces in an engine (ex: crankshaft main bearings) have very tight tolerances, usually in the 15-25 thousandths of an inch. The engines oil pump fills those tiny gaps with pressurized oil which allow the metal surfaces to spin thousands of times per minute without damage. This is also why if you have any issue with oil pressure (ex: oil pump failure, cracked oil line) or oil starvation (ex: driving a regular car on a race track, cornering forces slosh oil away from the oil pickup in the sump) issues, you'll damage your engine nearly immediately.
- LeifCarrotson 3mo agoIt's 0.0015, that's 1.5 to 2.5 thousandths, or 15-25 "tenths" as they're called. That's not a particularly tiny gap in the machinist world, it's large so that you can pump viscous oil in it and deal with a wide variety of temperature changes. 25 thousandths would be sloppy, a nominal clearance hole for a 1/4x20 bolt is about that much.
- arlattimore 3mo agoGood catch, sorry should have corrected that. While not small for a machinist, I think by the average persons definition that is a pretty small gap for the oil to occupy ;-)
- cagey 3mo ago> 25 thousandths would be sloppy, a nominal clearance hole for a 1/4x20 bolt is about that much. Isn't that 0.250 which would be 250 thousandths?
- teraflop 3mo ago
- CraigJPerry 3mo agoThe thing that's missing here that really drastically changes the story is all the emissions control hardware that would exist on such an engine. This is a circa 1990s engine in the US market i think? Dual Overhead Cam didn't really become popular in the US market until then i think. 70s-80s for single overhead cam to become established. The diagrams are beautiful and informative as always from this author.
- MarkusWandel 3mo agoWonderful but it irritates me that so many descriptions of internal combustion engines refer to "explosions" of the fuel. You don't want that. It causes knocking and pinging and engine damage. You want a controlled burn that generates heat smoothly.
- stouset 3mo agoYou don’t want detonation, but you do want deflagration.
- Toutouxc 3mo agoNot exactly. You do want a deflagration and not a detonation, but "explosion" is more loosely defined and, depending on who you're talking to, a self-sustaining subsonic flame front and a sharp pressure spike are a perfectly valid explosion.
- raffael_de 3mo agoexplosion/detonation causes engine knocking or pre-ignition which is both very bad. a properly working combustion engine is driven by controlled burning.
- Toutouxc 3mo agoYou’re replying to a post that says that “explosion” doesn’t imply “detonation”.
- raffael_de 3mo agoand that is not strictly correct. it's called combustion engine and not explosion engine for a reason.
- kube-system 3mo agoBut it is strictly correct. Deflagration is the definition of low (i.e. subsonic) explosive. Combustion is a broader term — combustion just refers to burning. And the reason it is called an internal combustion engine is to contrast it from its predecessor combustion engine designs - the external combustion engine. More precisely, the type of combustion happening in an ICE engine is (low) explosive. https://en.wikipedia.org/wiki/Explosive#Low https://en.wikipedia.org/wiki/Explosive#Low
- mberning 3mo agoIf you like this kind of stuff go and look up videos on the Rolls Royce Crecy engine from WWII. Absolutely insane engineering that died due the dawn of jet propulsion.
- relaxing 3mo agoVery interesting technology. Would be exciting to see a hardware startup build a product around this.
- darkteflon 3mo agoHmm not sure about that. It seems like a lot of complicated effort to produce locomotion. I’ll stick with my reliable horse, thanks.
- londons_explore 3mo agoWorth noting the design of the internal combustion engine hasn't changed much in 50 years. The thing that has changed is the control systems. What used to be a primitive mechanical way of mixing fuel and air (the carburettor), is now an electronic fuel injection system, with the fuel air ratio very carefully matched to reduce pollution (fun fact: modern cars release so little carbon monoxide, you won't kill yourself by starting one in a garage (but don't try it just incase your car is faulty)). Catalytic converters use any tiny fuel air imbalance to reduce carbon monoxide and soot, and on the other side nitrous oxides, by slightly increasing and decreasing fuel air ratios.
- pak9rabid 3mo agoThere's also been advancements in cylinder head technology (i.e., VTEC, VVT, etc), which I guess also falls under control systems, but worth mentioning as these technologies are very cool. Honda's iVTEC has it down to a damn science with how to optimize valve lift & duration across the entire RPM spectrum.
- OptionOfT 3mo agoWhat I am surprised by is that cams are still used to operate the valves. Given to how precise these need to be these days, I would've guessed they would've switched to electronically actuated valves.
- jballer 3mo agoI was going to point to Koenigsegg’s Freevalve system and, in the process of looking for a link, learned that it was cancelled.
- pseudoralph 3mo agoFiat (and other's I'm sure) have the [MultiAir system](https://www.caranddriver.com/features/a16580674/fiats-multiair-valve-lift-system-explained/ https://www.caranddriver.com/features/a16580674/fiats-multia...) which doesn't use cams to actuate valves And here's an example of someone that retrofitted a Miata to use a similar [air-actuated valve system](https://youtu.be/E9KJ_f7REGw https://youtu.be/E9KJ_f7REGw)
- jtwaleson 3mo agoI'm showing this page to my team and investors every couple of weeks. Visual, animated explanations are MUCH better than textual content for deeply grokking something. This is what we're trying to build for large software systems. I love the animations on this site so much, thank you for building them.
- nickvec 3mo agoI hope Ciechanowski posts some more in the near future. He has some of the best "how does this work" articles I've come across.
- drayfield 3mo agoAlways good to revisit his older work, though I admit I did get excited that it was a new post!
- duped 3mo agoThis is a stupid question but I'm a stupid EE/SWE who knows very little about physical objects. In the all these animations of the pistons I see linear motion translated into rotary motion using the crank shaft - but how do you design the pison/crank to always turn clockwise or counter clockwise (based on how you view it, obviously)? Is it possible for the crank shaft to lock up if it's perfectly oriented at 0 degrees?
- pjc50 3mo agoThis is why the starter motor spins the shaft in a known direction.
- aw1621107 3mo ago> but how do you design the pison/crank to always turn clockwise or counter clockwise (based on how you view it, obviously)? You can design the starter motor to ensure the engine always starts up moving in the right direction, and after that it's "just" a matter of timing (e.g., spark plugs controllled electronically in more modern cars, mechanically in older ones). > Is it possible for the crank shaft to lock up if it's perfectly oriented at 0 degrees? That's what the starter motor is for!
- reorder9695 3mo agoThe starter motor turns the engine in a defined direction, this acts as a turning force directly on the crankshaft so it doesn't matter where the crankshaft is. The pistons only start firing after the crankshaft is already moving. It is actually possible for an engine to turn the wrong way, this occurs on motorbikes with kick starts. When you don't kick start it correctly (or if the ignition timing is way out), a piston can fire prematurely before top dead centre and force the crankshaft against the direction that the kick lever turns it, this is known as kick back and is about as fun as it sounds when the engine's force goes through the kick lever.
- jabl 3mo agoSome engines, nowadays mostly large marine diesels, are reversible. Change the valve timing, and start it in the opposite direction, and off it goes.
- deleted 3mo ago[deleted]
- gwbas1c 3mo agoWhen I was a kid, pre-internet, my dad took me to the local library and checked out some books that explained how an engine works. These animations are so much better than what I had!
- klaff 3mo agoWhen I was a kid we had a visible V8 model that let you see quite a bit!
- vjvjvjvjghv 3mo agoThis should probably be called “Four Strike Engine”. There are other types of ICE that work differently.
- yunnpp 3mo agoYou mean stroke?
- vjvjvjvjghv 3mo agoYes. I think the iPhone keyboard tricked me again. I remember having to work quite a bit to convince it to take "stroke" instead of "strike" and I guess it finally decided at submission to go back to "strike".
- dotancohen 3mo agoFour stroke. And why not call it "Four cylinder four stroke ICE" or "Inline four cylinder four stroke ICE" or "Inline four cylinder dual overhead cam four stroke ICE"? Of course there are other forms of ICE, the description does not need to detail exactly which subtype is described.
- rootusrootus 3mo agoI still remember the first time I tore down a pushrod V8. I decided it had to be close to the pinnacle of elegant design. Nothing wasted, everything had a purpose, and it all came together in a perfect mechanical symphony. We have since made engines which are significantly more efficient and powerful, but all of that at the cost of elegance, slapping on overhead cams and machinery just to adjust the valve timing, etc. Fantastic technology in it's own right for certain, but feels tacked on, like an expensive optimization. Reminds me that I want to get something for my kids to work on which will maybe show them some of that same elegance. I don't currently have any V8s in the garage to go tear down :)
- deleted 3mo ago[deleted]
- plasticeagle 3mo agoWho is this person. A beautifully written and illustrated explanation of a fascinating machine. A website filled with other explanations of other things, also wonderfully written and clearly explained. An instagram filled with beautiful landscape photographs, an "X" page consisting only of links back to this blog, and a Patreon with hardly any more information that that. I love this. Fantastic content. Zero ego. And if there was any AI use, it's invisible. Certainly there is none in the writing.
- yunnpp 3mo agoThere is no AI use here. I'm somewhat offended by the suggestion even though I have no relation to the author. Bartosz has been shredding for a long time now. His javascript is also unminified and perfectly readable, making it a great reference for study despite not being advertised on his pages. The animations are all hand-made. The guy is cooking. To suggest that any of it is AI is an utter blasphemy. AI is for noobs, grifters, and low-effort content farmers and Bartosz isn't any of those things.
- plasticeagle 3mo agoI agree completely, and if you re-read what I wrote I didn't exactly suggest that it was used. But if he's reading this I'd hope he'd nevertheless accept my apology for even the hint of a suggestion. Happy to find someone else who hates that infernal technology as much as I :)
- RecycledEle 3mo agoThis is an excellent explanation! Thank you!
- userbinator 3mo agoWhile they look perfectly round, piston skirts are actually slightly oval. ...something which has been the case for at least 80 years: https://news.ycombinator.com/item?id=15397926 https://news.ycombinator.com/item?id=15397926 (the article in that link has now moved to https://www.web.imperialclub.info/Repair/Lit/Master/003/index.htm https://www.web.imperialclub.info/Repair/Lit/Master/003/inde... )
- linzhangrun 3mo agoThere is a very good engine simulation software: https://github.com/Engine-Simulator/engine-sim-community-edition https://github.com/Engine-Simulator/engine-sim-community-edi...
- ggm 3mo agoWhy does this show a 4 cylinder engine firing as two pairs? My ignorance is on display, surely it's more subtle and there are 4 distinct phased firings not two?
- edot 3mo agoThere are four distinct firings. Look for the little yellow poofs. The pistons move in pairs for balance (vibrations). Each piston is doing one of the four strokes (suck, squeeze, bang, blow is the crude way to remember) at a given time. None of them are doing the same thing at a given time.
- ggm 3mo agoThank you. TIL!
- mcmoor 3mo agoIt's unclear to me, why would the compression stroke (the 2nd out of 4) happens? There's nothing pushing the piston upwards.
- Gebees 3mo agoIt's being pushed up by the crankshaft which keeps moving because of the inertia of the moving engine parts, especially the flywheel. On multi-cylinder engines, other cylinders add torque at different phases of the rotation.
- sscaryterry 3mo agoThis is what I think learning should look like. Interactive, high-definition, 100% functioning of something you are studying. If only we can use LLMs for good, to create stuff like this.
- rclabs 3mo agoI remember as a teenager trying to understand what made rally cars go bang-bang, by modifying the ignition timing among other things, those gases hit a hot exhaust manifold where they create a mini explosion that keeps turbo spooled.