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Internal Combustion Engine

ciechanow.ski

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Re: Internal Combustion Engine

#221

Post by addison-lee »

keanebean86 wrote: post #127
toxik wrote: post #79

This was excellent, but should perhaps be clarified that this is a gasoline engine - diesels don’t ignite by spark, but by immense pressure in the chamber. This also invalidates the “you cannot add fuel to increase power” of gasoline engines. Diesels can (and should!) run at lower rpm; they don’t stall because the ECU can add fuel to increase power output.

What I want to try is replacing valves with electric iris mechanisms. The computer would signal the iris to open or close depending on the situation. No more complicated variable valve stuff. Just hold the iris open longer. Also no more interference engines and timing chain/belt changes. Iris: https://commons.m.wikimedia.org/wiki/File:Iris_Diaphragm.gif Edit: fixed typo, added link to iris gif

I don’t think an iris like that would last very long with the immense pressures in the cylinders. It makes way more sense to electronically control the valves themselves, like Koenigsegg is doing with their Freevalve tech, so you get the mechanical seal of the valve with the control of electronics.

Re: Internal Combustion Engine

#222

Post by Prcmaker »

samstave wrote: post #88
kirse wrote: post #43

Earlier quoted context omitted.

Subaru EJ motors munch through rod bearings quite happily.

What are the indicators that replacing them is neigh?

In my experience with these, when I've heard the first indicator to do it, the damage is done. Standard regular maintenance hasn't identified the issue in advance. I'd be curious to see whether long term monitoring of particulates in oil can make an help though.

Re: Internal Combustion Engine

#223

Post by addison-lee »

mgarfias wrote: post #89
incomplete wrote: post #12

as someone who as a hobby occasionally builds engines (for the 24 hours of lemons), i was really impressed at how incredibly accurate and detailed this whole page is. i'm down w/TDC...

I wasn't. But then I've literally been working on engines since i was a little kid.

Quality contribution!

Re: Internal Combustion Engine

#224

Post by arh68 »

mrfusion wrote: post #189

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

Rubber with embedded steel wire is less stretchy than the rubber bands we're used to. Tires even more so than belts; it adds integrity like rebar in concrete.

You're correct that once it jumps even 0.5cm (~1 tooth) it could touch piston to valve; it depends on the engine, but I'd wager most nowadays are interference.

Re: Internal Combustion Engine

#225

Post by BlueTemplar »

qwertox wrote: post #164

One of those web pages which deserves an award. Some place in some kind of Internet Hall of Fame, an historical archive which shows the only best highlights of what websites were actually capable of presenting. Milestones of web development. This page summarizes pretty good what web technology is capable of, when in the hands of a real professional. --- Ok, I just realized this is from Bartosz Ciechanowski, and this…

Yeah, and to think that some people are incredulous when I say that I need animation support in my electronic documents !

This is even better, I will bookmark it as an example.

Re: Internal Combustion Engine

#226

Post by ekianjo »

What is the best way to archive such a page for offline browsing? I tried ArchiveBox on this, but all the animations are gone in the offline version (no matter which method was used).

Re: Internal Combustion Engine

#227

Post by chrisdalke »

therein wrote: post #208

I have always wondered, if it would be possible to make a small enough internal combustion engine so that you could just have it laying around in an apartment, sitting a few feet away from you, powering your appliances or charging a 12V or 24V battery. Dispensing the exhaust through a long tube. If all goes well, complete combustion of propane should yield CO2 instead of CO anyway. An additional enclosure shouldn't b…

For sure miniature gensets exist! They're often used on gas RC / autonomous airplanes to generate supplemental electricity. Here's one: https://www.youtube.com/watch?v=1yB49G756OI

I think the answer is that the miniaturization reduces efficiency, adds a ton of tiny, expensive parts/maintenance, and doesn't generate a lot of power compared to what you can store in a battery. So while the idea is cool, it's really only applicable in a few specialized use-cases like long-duration drone flight.

You've got to also compare it to other available power generation schemes -- A single 250W solar panel is far cheaper, simpler, and eco-friendly.

Re: Internal Combustion Engine

#228

Post by elihu »

Alupis wrote: post #194
elihu wrote: post #183

Earlier quoted context omitted.

It's funny you mention the RX-8, since I'm in the (slow) process of converting one to electric. That weird cat blower was one of the many parts I removed while thinking "I'm glad I don't have to understand or care about why this car needed something like that in the first place".

Just talking about the RX-8 brings back great memories - what a strange, yet beautiful car! The cat blower, and the subtle whining sound it made when you started up cold was one of the ways every RX-8 owner was hazed into the fold... after calling the dealer or posting on a forum and finding out it's entirely normal! Other oddities included how it deliberately burned oil (scaring new owners into thinking they had a s…

I'm hoping LiquidPiston's rotary engine design pans out: https://news.ycombinator.com/item?id=25450477

In theory, it should fix some of the maintenance issues (apex seals are attached to a stationary part of the engine where they can be more easily lubricated) and fuel efficiency / emissions issues (combustion chamber is closer to spherical).

I like the idea of the Mazda rotary engine, but I'm not really surprised they stopped making them, due to fuel economy and emissions. And at them moment, the hundred-thousand mile engine rebuild interval basically means you can get an RX-8 with a bad engine for almost nothing, which opens up a nice opportunity for EV conversion. It's hard to imagine a nicer platform to start from.

Re: Internal Combustion Engine

#229

Post by baybal2 »

therein wrote: post #208

I have always wondered, if it would be possible to make a small enough internal combustion engine so that you could just have it laying around in an apartment, sitting a few feet away from you, powering your appliances or charging a 12V or 24V battery. Dispensing the exhaust through a long tube. If all goes well, complete combustion of propane should yield CO2 instead of CO anyway. An additional enclosure shouldn't b…

Yes, first 40% efficient ICE was made almost a century ago, but those were very big engines.

Re: Internal Combustion Engine

#230

Post by baybal2 »

kingsuper20 wrote: post #26
bob1029 wrote: post #11

Earlier quoted context omitted.

Reciprocating machines are fairly remarkable when you consider all of the components involved, forces, etc. Even more so when you think about how long a typical car engine lasts. These incredible forces are why rotary and turbine engines are substantially more reliable. Some gas turbines have only 1 moving part, and in some applications this moving part experiences zero wear due to magnetic/aerodynamic/active bearing…

Rotaries are a funny case. Look good on paper. Thermal efficiency issues. Smog. Seals. Noise control difficulties. Weird patches like bridge ports. For modern passenger cars, it's kind of like overcoming the difficulties of two-stroke. In anti-defense of 4-stroke ICE, it seems to me like we are hitting peak wacky complexity of those. Variable timing cams, turn off the cylinders, direct port injection, turbos, variabl…

The problem with ICE industry is that nearly nothing improves much in absolute terms.

If you take a look at list of ICE records, nearly all of them were made decades, and decades ago.

Biggest piston engines - early 20th century

Most powerful piston engines - fourties

Most efficient piston engine - Jumo 204 held the record until nineties

Most power to weight - eighties

Uncounted billions put into engine RnD were mostly about scraping last few percents off everything above, and environmental compliance.

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