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Comment by bogomipz | Hacker News Reader

>"Most internal combustion engines are only good for ~200,000 miles"

Interesting and I think that figure is is generally accepted and I believe this is due to shear stress on the engine block no?

I know older cars that came out of Detroit when engine block were cast iron could get up to ~300k miles(the slant 6 comes to mind) but I believe nearly all engine blocks in recent makes are aluminum now.[1] The referenced article says there's parity between now between the two but that doesn't correlate with my own admittedly limited and anecdotal observations.

[1]http://articles.latimes.com/2000/oct/18/news/hw-37969

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> due to shear stress on the engine block no?

What kills piston engines is sliding friction.

Unavoidable sliding friction on pistons, valves, and camshafts results in wear. The crankshaft journal bearings are partially lubricated and wear out. Because on the power stroke the film of oil between the crankshaft bearing and the crankshaft gets squeezed out resulting in direct contact. Fully lubricated journal bearings generally last 'forever'

Even if you solved the above problems, some parts like springs, valve seats, and other moving parts would eventually suffer from fatigue.

Interesting calculation to make it to look at the lifetime of automotive engines in terms of hours. 200,000 miles divided by 30 mph gives a lifetime of 6600 hours. Compare with industrial electric motors and gear trains where life times of 50,000 hours are common and you can see where things are going with electric cars.

All of this is true, but in my experience, it's the rare engine that meets its end due to piston/cam friction. Usually, the engine is abandoned due to the cost of maintaining all the things attached to it (e.g., water pump, alternator, master cylinder, etc.). If you're willing to suffer the nickel and dime expenses, the actual pistons/valves/camshafts usually last many hundreds of thousands of miles.

EVs don't have as many things attached to the engine. I wonder if some "new" EVs will just be refurbished older EVs with a new battery and cosmetic changes.

People want new bodywork, seats, electronics, etc.

It might be possible to make all that replaceable, so that a car can be fully refurbished, and certainly that is done to commercial vehicles all the time (passenger buses, etc.), but not sure about the economics of doing it to light-duty cars and trucks. The body itself is probably not that expensive.

Certainly seems like it ought to be possible to pull the motors out of an old car and drop them into a new one. But then again people do that with gasoline engines all the time, too. If you blow a head gasket in a lot of cars, the "fix" is often to replace the engine with a remanufactured engine that comes out of a crate. It's cheaper to do that than to pay for the labor to actually replace the gasket in a shop, at least in a high-cost area (NE US, especially at dealers).

GM had their "skateboard" concept with the idea of swapping bodies on a general platform (it was also completely drive-by-wire).

I could see springs, but most new vehicles have hardened valve seats that don't need tretraethyl lead for lubrication.

Ferrous metals, when used in a correctly designed part, have a near infinite fatigue life.

https://en.m.wikipedia.org/wiki/Fatigue_limit

Most wear is during startup before oil pressure comes up. Some aircraft engines have electric oil pumps, so that oil pressure is at 100% before the engine starts. It's common to bring up oil pressure before starting on very large Diesel engines (ships, earthmovers, tanks) to extend the life. Those usually have a starting engine to provide startup power. Large diesels are often cranked with no compression (all valves lifted) and no fuel flow to get things well lubricated before combustion starts.

Auto engines could be run that way, but the slow cold start process acceptable for heavy equipment would annoy motorists.

> Compare with industrial electric motors and gear trains where life times of 50,000 hours are common and you can see where things are going with electric cars.

To be fair, industrial engines (for generation and the like) reach 20-30k hours.

It is generally accepted, but I'm not convinced that it is true. I suspect that most cars get replaced well before the engine's ultimate fairly.

In my own (anecdotal) experience, they burn a little oil at 200k, but have plenty of life left in them.

In the days of the Slant-6, cars never got to 300k miles unless they had ridiculously meticulous maintenance. Detroit cars were lucky to get to 100k without falling apart. These days, cars are barely broken-in at that age, and 200k is nothing remarkable. If you're not getting that kind of lifetime, then you need to stop buying a crappy brand.

>"In the days of the Slant-6, cars never got to 300k miles unless they had ridiculously meticulous maintenance"

As the former owner of mid 1960s Slant 6 purchased with ~ 220K miles on it that I personally put another 120K before the block cracked I am telling you that you claim of "never" is just plain wrong.

Aside from periodic oil changes I wouldn't describe my maintenance regime as ridiculously meticulous at all.

There are many vintage Duster/Dart/Valiant owners with cars that have 200K and greater miles on them. Here are some links with attestations that corroborate this fact:

http://www.forabodiesonly.com/mopar/threads/who-has-the-high...

http://www.onallcylinders.com/2014/01/20/top-10-engines-time...

http://www.nytimes.com/2003/12/15/automobiles/autos-monday-c...

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ttal...

How ironic that you put it that way, considering that I've known slant 6s with 300K on them. I don't know if they all did that, as I've never known a slant 6 to die, so I'm not knowledgeable of their average life. And every small block Chevy (of that era or a little later) I've owned or knew the owner could easily top 100K. The later American compact four cylinders, OTOH...

Indeed. Both he Chevy small block 350 and Dodge Slant 6 are both considered legendary designs.

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