[HN Gopher] Porsche's idea for a six-stroke internal combustion ...
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Porsche's idea for a six-stroke internal combustion engine
Author : tempestn
Score : 155 points
Date : 2024-09-21 06:15 UTC (16 hours ago)
(HTM) web link (www.motor1.com)
(TXT) w3m dump (www.motor1.com)
| teo_zero wrote:
| But isn't the chamber full of exhaust at the beginning of the
| second power stroke? What will burn?
| OJFord wrote:
| It says the goal is efficiency, so I assume the point is that
| if the first does say 80% combustion, then another cycle eeks
| out another 80% of 80% or whatever. (Brb, have an 8 stroke
| engine to patent.)
| OJFord wrote:
| Oops, another 80% of the remaining 20%, I mean. (But also I
| would guess it is probably less efficient than the initial
| one, not another 80%.)
| UniverseHacker wrote:
| When Porsche says efficiency they mean making more power, not
| using less fuel. Porsche has a long track record of adopting
| efficiency tech and using them to make fast cars that still
| use a ton of fuel.
| dahart wrote:
| What's the difference between getting more power out of a
| given quantity of fuel, versus using less fuel to achieve a
| given power output?
| serial_dev wrote:
| Extremely simplified, when you drive a sports car, you
| want to maximize power (work per unit of time), period,
| you don't care about fuel.
|
| If you want to go the farthest with a full tank, you want
| to maximize the total work (proportionate to traveled
| distance) for unit of fuel.
|
| Reality for practically all cars are between these two
| extremes, you want to enjoy driving, go relatively fast,
| and still not wasting 25 liters for traveling 100 km.
| dahart wrote:
| Those are correct statements that don't answer the
| question I asked. You've explained the difference between
| not caring about efficiency and caring about efficiency.
| The article said the 6-stroke design is for "efficiency"
| and did not say Porsche doesn't care about fuel and only
| wants to maximize power, contrary to the comment I
| replied to above. If an engine gives you more power with
| a fixed quantify of fuel, then it must also give you less
| fuel for a given quantity of power, right? There's no
| such thing as more efficient only for power.
|
| BTW Porsche makes consumer vehicles, not just race cars.
| And they make engines for other types of vehicles, not
| just cars. It's ridiculous to claim that Porsche doesn't
| care about fuel just because they happen to make some
| race cars. Nothing in the article suggests this design is
| for a race car, nor would it; a patent is designed to be
| broadly applicable and if a 6-stroke design is shown to
| be more efficient than a 4-stroke design for fuel-
| efficient consumer cars, you can bet Porsche will be
| happy to sell you the engines or license the design.
| Ccecil wrote:
| My assumption is there is a context difference.
|
| Efficiency in fuel/mile. Efficiency in Power output/liter
| of displacement.
|
| But that is just my assumption.
|
| You can have a relatively small engine and force a ton of
| air/fuel into it under boost and get tons of HP but it
| tends to lose the ability to maintain fuel economy. Tune
| it for fuel economy and it tends to lose power. It is
| very difficult to have both in the same package for many
| reasons. Adding mods like discussed in the article start
| to allow for the overlap to be wider.
| OJFord wrote:
| I'm not sure if that's supposed to be a correction, but if
| so I don't understand. The description of the two new
| strokes is as an addition to the normal four, one of which
| is the fuel intake, I was not assuming that decreases in
| quantity or anything. It could do, it's just orthogonal to
| the point - if you don't entirely combust _whatever_ amount
| you inject in the first ignition , then the idea here aiui
| is to compress & ignite again to, yes, get some more
| 'power' out of it.
| randerson wrote:
| A recent example of what (I think) the parent is saying,
| is the new 911 GTS which is now a T-Hybrid [0] engine.
| But the electric motor doesn't give it better gas mileage
| than its predecessor, it is just used to eliminate turbo
| lag which allows them to use a bigger turbo, giving it
| more horsepower, and using a leaner fuel mixture at full
| throttle to meet the latest emissions standards.
|
| [0] https://www.caranddriver.com/news/a60914997/2025-pors
| che-911...
| nikanj wrote:
| You can overfill the cylinder for the first stroke, because the
| unspent fuel will burn on the next cycle instead of being
| exhausted.
|
| High power engines exhaust a lot of unburned fuel, because you
| can't guarantee an exact 100% fill for the cylinder, and
| there's more power to be had at 120% fill than 80% fill.
| Oversimplified of course.
| ethbr1 wrote:
| But you don't have an additional intake stroke, so there's
| limited oxygen in the second power stroke to burn.
|
| It sounds more like they're running fuel-lean, then possibly
| adding more fuel before the second compression stroke.
| Neil44 wrote:
| Maybe the first cycle is super lean, leaving lots of O2 and CO
| still to burn.
| Szpadel wrote:
| that might be something similar to why diesels mix exhaust gas
| with fresh air, but that might be just to purify exhaust gases
| better - I'm no expert
| Maledictus wrote:
| Given there is enough oxygen left, they can inject more fuel.
| HPsquared wrote:
| Sounds like EGR
| yobbo wrote:
| Might also be possible to inject water into the compressed
| exhaust gasses. The water evaporates and creates the second
| power stroke, while lowering the temperature of the exhaust
| gasses. There's quite a lot of energy left in the exhaust
| gasses otherwise.
|
| This is not a new idea but it creates mechanical complexity and
| higher requirements on the materials of the piston and
| cylinder.
| Ccecil wrote:
| 6 stroke diesel prototype.
|
| https://www.autoweek.com/news/a2063201/inside-bruce-
| crowers-...
|
| edit: Description before link
| labcomputer wrote:
| It looks like the patent describes a weird hybrid of a
| conventional 4-stroke and a uniflow 2-stroke.
|
| At the bottom of the first power stroke, the cylinder drops
| lower to expose scavenging ports. That both forces air in (at
| the bottom of the cylinder) and helps push exhaust out (through
| conventional exhaust valves).
|
| Uniflow 2-strokes tend to have high thermal efficiency, but
| poor emissions, especially particulates. So the idea here might
| be to gain some efficiency without another emissions-gate.
| everyone wrote:
| I'd love to see a decent effort with some funding behind it to
| make a rotary vane engine..
| https://youtu.be/UPFFXBAe5mc?feature=shared
| bell-cot wrote:
| Not to say that modern IC engines are any sort of "simple"...but
| there appear to be a lot more high-precision moving parts, under
| load, in their clever new crankshaft assembly. (Vs. traditional
| 4-cycle IC engines.)
|
| Obviously, Porche's target market isn't likely to care about
| that.
|
| But for possible down-market uses of this technology - are there
| any mechanical engineers in the house, to comment?
| UniverseHacker wrote:
| I drive a 24 year old Porsche and the engine already has a lot
| more mechanical complexity than most other engines- especially
| for their variable camshaft timing system. You're right that
| Porsche and their target customers don't care much. I'd say
| German engineering culture in general is to make things work
| better (when new), and not worry about complexity.
| nolan879 wrote:
| I Do Cars did a tear down of the M96 engine from a 986
| Boxster S. Seeing inside of them, it makes sense how these
| motors cost $20K to teardown, rebuild and remedy Porsche's
| cost cutting in their first water cooled engine. I would own
| another 986 or 996 in a heartbeat. Tear down video:
| https://youtu.be/qrkALiq5hTU?si=0OmBKYcim-cflJEy
| brookst wrote:
| Not a ME but many modern ICE's have tons of mechanical
| complexity in the valvetrain to handle varying timing and lift.
| From multiple valves driven by different camshafts to various
| ways to switch between camshafts or rotate cams, this stuff
| gets crazy.
|
| Presumably Porsche's design still has all of that, too.
| magicalhippo wrote:
| I'm a programmer, not an engine guy. From the description in the
| article, they do one intake stroke, two pairs of compression-
| power strokes, followed by an exhaust stroke.
|
| Also, it seems the initial compression-power strokes are done
| with the piston moving lower, ie both lower top dead center and
| bottom dead center, hence would have lower compression, and the
| second moving higher so with higher compression.
|
| From my understanding of more fuel means less compression is
| tolerated before knocking[1], and vice versa.
|
| So do I understand it correctly that their idea then to make the
| first power stroke rather rich with lower compression ratio to
| eliminate knock, and the second at a higher compression ratio to
| burn the remaining unburnt fuel? Or the other way around, ie lean
| with high compression first?
|
| If so, it seems like an evolution of variable compression ratio
| engines[2].
|
| edit: my morning-brain is having issues with thinking about how
| air-fuel ratio change in rich-burning vs lean-burning scenarios.
| So perhaps they aim for a good stoichiometric ratio and rely on
| the exhaust gasses to avoid knock when increasing compression the
| second time around?
|
| [1]: https://en.wikipedia.org/wiki/Engine_knocking
|
| [2]: https://en.wikipedia.org/wiki/Variable_compression_ratio
| i_am_jl wrote:
| >more fuel means less compression is tolerated before knocking
|
| Generally, no.
|
| Knocking happens from pre-detonation, that's usually caused by
| heat from compression causing the fuel/air mix to ignite before
| it's triggered by spark.
|
| To avoid this engines will run a fuel/air mix that is not
| stoicheometrically ideal, to make the mixture less likely to
| ignite early.
|
| It is safer to run a fuel rich mix than to run a fuel lean mix
| as it keeps combustion chamber pressures low (unburned fuel
| takes heat out of the exhaust). It is more economical and more
| ecologically friendly to run fuel lean since you paid for that
| unburned fuel and it's kinda gross.
|
| In general, more fuel than ideal means more resistance to
| knock. But these things are complex.
|
| EDIT: Knocking happens from pre-detonation. Knocking can also
| happen from predestination, like in the case of turbocharged
| Subarus.
| MrDunham wrote:
| Friendly correction for others because your auto correct
| failed you...
|
| "predestination", pretty sure parent meant "pre-detonation"
|
| A.k.a. Autoignition aka "it goes boom before you planned on
| it"
|
| Only adding this as it's a pretty crucial word for
| understanding the comment.
| rpmisms wrote:
| That fuel is totally depraved, and has no hope of
| salvation.
| cout wrote:
| This is why TULIP oil makes a great fuel additive.
| i_am_jl wrote:
| Ah you're right, thank you!
| magicalhippo wrote:
| Ah yes, read that engine knock article the wrong way around,
| guess my mind was drawing on intuition from things like gun
| powder where more stuff crammed more tightly together is
| worse.
|
| So then, _if_ they 're doing a non-ideal initial burn it
| would have to be a lean lower-compression burn, followed up
| by a higher-compression secondary burn?
| i_am_jl wrote:
| I am sure that I don't understand the specifics of what
| Porsche is doing, but the article says the cycle is intake-
| compression-power-compression-power-exhaust. For that to be
| the case they have to be burning the same fuel and air
| mixture twice, and I don't understand the chemistry there
| enough to even speculate how it works.
|
| I think it's safe to assume that the second stroke is
| burning incomplete combustion products left over from the
| first stroke. I think that the second compression stroke
| would have to be higher compression than the first in order
| to get more complete combustion of what's left behind.
| Ccecil wrote:
| That actually makes a lot of sense merging with some
| comments from above.
|
| Second stroke goes lower and there are some ports to add
| air which are not accessed during the initial compression
| stroke...so the stroke is longer (higher compression) and
| more air is added to help with the reburn.
|
| Kinda sounds like combining the idea of the Miller cycle
| with a variable compression/stroke setup (see Nissan).
|
| There are a lot of ideas out there that create gains
| individually...glad to see them being combined more and
| more in modern engines. (ex. VRIS, VVT, DFI,) I
| personally think there is still another few decades of
| playing around with ICE to be done...not sure it will be
| viable for the market...but the research will lead to a
| lot more interesting engineering.
| lloeki wrote:
| > Miller cycle
|
| Heh all along I'm wondering, what kind of thermodynamic
| cycle is it? By six strokes, does it mean there are
| actually distinct new phases to the PV graphs compared to
| Atkinson/Carnot/Miller?
|
| Or is it just masquerading a well-known cycle underneath
| six strokes, only some parts are being optimised?
| Ccecil wrote:
| Not sure myself...
|
| Seems to be like it is a Miller cycle (or could be) on
| the initial 4 strokes. Which would allow you to control
| the timing of the "Compression max point" in the stroke
| by varying the boost. That may also vary the amount of
| spent fuel remaining for the second "scavenge"
| stroke...which if I am reading comments above correctly
| it pulls air from ports lower in the cylinder which would
| help clear the cylinder for the next 4 stroke cycle.
|
| Seems to me more focused on reburning/scavenging to make
| a "cleaner" burn than anything else though.
|
| *Not an engineer...just a shadetree mechanic who reads
| too deep into engine papers.
| magicalhippo wrote:
| Ah, extra ports, that makes a lot more sense. I had
| missed that detail.
|
| So the first phase is like a regular 4-stroke engine, and
| the second phase is more like 2-stroke engine, where
| extra air (and possibly fuel) is introduced into the
| cylinder, like a 2-stroke, through ports located below
| the position of the piston during the bottom dead center
| of the first phase.
|
| So I guess you have something like intake (high),
| compression (high), power (high->low), compression (low),
| exhaust (low->high), where in parenthesis is the
| adjustable piston height?
|
| So a richer higher-compression first phase, followed by a
| leaner lower-compression second phase?
| Ccecil wrote:
| I suspect the second stroke is higher compression. First
| stroke has the compression "shape" controlled by the
| boost (miller cycle).
|
| With direct injection they could even be injecting more
| fuel into the cylinder for the second stroke...but I
| suspect the second stroke F/A ratio is determined by the
| first stroke remnants combined with the extra air allowed
| in at the bottom of the second stroke.
|
| All of this with the cam variators, timing control, boost
| control and fuel setup that VW already runs would be
| fairly easy to control with the proper sensors and code.
|
| Just speculating at this point...but it makes sense to
| me.
| magicalhippo wrote:
| Finally got time to read a bit of the patent, which talks
| about two TDCs and BDCs, which I'll denote as "high" and
| "low", as related to the distance of the piston to the
| crankshaft. So the high TDC has maximum compression, and
| low BDC has the maximum cylinder volume, and the
| scavenging port(s) are between high BDC and low BDC.
|
| Unless I screwed up my notation shift, the strokes from
| the patent are as follows:
|
| 1. Intake (low TDC -> high BDC)
|
| 2. Compression (high BDC -> high TDC)
|
| 3. Power (high TDC -> low BDC)
|
| 4. Compression (low BDC -> high TDC)
|
| 5. Power (high TDC -> high BDC)
|
| 6. Exhaust (high BDC -> low BDC)
|
| So during the first power stroke, stroke 3, the cylinder
| moves from "high" to "low" and thus is the longer power
| stroke. Also during the second compression stroke, stroke
| 4, the cylinder position moves from "low" to "high". So
| technically leading to higher compression ratio. I was
| thinking it would cost too much energy to do so, hence
| dismissed that alternative, but I guess not.
|
| The patent also notes that the extra scavenging ports are
| not needed, fresh air-fuel mixture can be introduced via
| the inlet valve(s) while the piston moves between the two
| BDCs.
|
| Would be fun to try to simulate it in Ange's engine
| simulator[1].
|
| [1]: https://github.com/ange-yaghi/engine-sim
| Ccecil wrote:
| I would imagine that pulling the air from the bottom
| would help more with scavenging the cylinder than the top
| but yeah...I can imagine it wouldn't matter.
|
| That all makes sense. Pretty much what I assumed. The
| compression stroke at #4 is the longest stroke. Then it
| also has the benefit of the Power stroke at #5 being
| shorter which will mean it will have the benefit of a
| short(er) stroke motor on the power (more torque?) during
| that cycle.
|
| The shorter stroke on #1 is desirable since you are using
| boost (I am assuming Miller cycle here) to control the
| beginning of compression as opposed to the intake valve.
|
| Once the mechanical timing is down I assume it isn't too
| bad to keep all in line though...but a mess if it gets
| out.
| hatsunearu wrote:
| Pretty sure it's just a way to get more expansion from the
| same air charge.
|
| It's a similar idea to the Atkinson cycle. You have
| dissimilar compression and expansion strokes. In normal
| engines, there's a limit to compression ratio because if
| it's too high, it causes knocking. But a bigger expansion
| ratio lets you extract more energy out of the combusted
| gas, which leads to higher efficiency.
|
| The original Atkinson cycle idea was to use some complex
| linkage to get dissimilar compression and expansion
| strokes, but the way it's implemented in things like the
| Prius is to have a high compression engine, but mess with
| the intake valve timing such that you only use a small part
| of that compression during the intake phase so you
| effectively handicap your compression ratio to avoid knock,
| while still retaining the full stroke during the expansion
| phase.
| hatsunearu wrote:
| >Knocking happens from pre-detonation, that's usually caused
| by heat from compression causing the fuel/air mix to ignite
| before it's triggered by spark.
|
| No, it usually happens because the normal flamefront from the
| spark causes a rise in pressure that triggers compression-
| ignition in other parts of the cylinder. It's not solely from
| the compression, usually. That scenario is rare primarily
| because as you reduce the knock margin, you'd hit knock from
| what I said before you get to the state where it's so bad it
| ignites from compression alone.
|
| https://www.researchgate.net/figure/In-cylinder-pressure-
| tra...
|
| Look at this picture; this is a typical waveform of cylinder
| pressure vs. crank angle. The spark happens 28 degrees before
| TDC, so basically the left edge of each of the graphs. As the
| flamefront consumes the air-fuel mixture inside the cylinder
| after the spark, the cylinder pressure gradually rises.
| During knock events, the cylinder pressure as risen by the
| normal combustion process gets to a point where it starts
| igniting the fuel elsewhere in the cylinder, away from the
| gradually expanding flamefront. This causes rapid combustion
| which causes the pressure to rise suddenly, which causes
| damage to the engine (if severe enough)
| cout wrote:
| This edit is brilliant!
| kopirgan wrote:
| Know nothing about automobile engineering but somehow this feels
| like Wordpress releasing a version for DOS when windows already
| captured most of the PC market.
| kopirgan wrote:
| Know nothing about automobile engineering but somehow this feels
| like WordPerfect releasing a fantastic version for DOS when
| Windows was already capturing all the market.
|
| Btw they did that. Rest is history.
| bayindirh wrote:
| Considering that people still love vinyl, automatic watches,
| fountain pens and hand made notebooks, I think this will still
| has its niche, and more interesting designs will follow to push
| the internal combustion engines forward.
|
| On the other hand of the spectrum, Hyundai Ioniq 5 _N_ can
| emulate a sports car with an internal combustion engine and 8
| speed sequential gearbox.
| mrangle wrote:
| ICE aren't niche, and there isn't strong evidence that they
| will be. There doesn't seem to be a public Come-to-Jesus
| moment for electric cars on the horizon. There seems to be
| solid reasoning behind that reluctance. That is, it will be
| difficult to displace. If phasing out ICE comes down to
| regulations only, then the antique interface analogy doesn't
| fit.
|
| >On the other hand of the spectrum, Hyundai Ioniq 5 N can
| emulate a sports car with an internal combustion engine and 8
| speed sequential gearbox.
|
| Sports cars are sometimes for vanity, which is a role that a
| Hyundai wouldn't fill. But you referenced driving
| characteristics. Fair enough, and so no need to talk about
| the vanity attraction of a future all electric Porsche. When
| not for vanity only, sports cars are for people who like a
| driving experience. Sports car culture is strongly critical
| of any deviation from an ideal experience even with better
| ICE cars. Therefore, it tends to detest "the other end of the
| spectrum" the most.
|
| Sports cars are integrating electric motors, but mostly as
| horsepower and torque supplements for ICE. The most well
| regarded sports cars for the common man err toward being
| ultra-light weight, relatively low power, and high rpm with a
| manual gearbox. With the rest being as analog as possible.
| With incremental deviations from that ideal only as preferred
| for specific owner comfort. None of that criteria speaks to
| an appropriate / desired role for an electric motor.
| freeone3000 wrote:
| >need to talk about the vanity attraction of a future all
| electric Porsche
|
| Future? You can buy an all-electric Porsche Taycan since
| 2019 - and it's faster than the 911.
|
| Sports cars are fully adopting electrification, due to the
| huge torque numbers and high scalability. M-B and BMW of
| course, but also Porsche and soon to be Ferrari. It's not
| just hybrids used for a boost (as in the decade past):
| those are full electrics.
| mrangle wrote:
| What's your point? Future or now, my point about vanity
| remains. I don't see any point in arguing over my use of
| the word "future" here.
|
| Again, "faster" isn't the most important metric for car
| enthusiasts. Which is what I described in my post. I know
| that's disappointing to people who would like it to be in
| order to claim total justification for electric motors.
|
| To say that "sports cars are fully adopting
| electrification" seems to want to imply that sports cars
| are moving mostly to full electrification. This isn't
| remotely true. Their customer base wouldn't stand for it.
| grvdrm wrote:
| Under-appreciated point you make: not about speed.
|
| I own a 2014 Boxster S. 315 hp, 266 lb/ft torque,
| 6-speed. It is NOT the fastest car out there. In fact I
| own an automatic 3-series BMW that's faster in a straight
| line every time.
|
| But the Boxster is under 3k pounds curb weight. It is
| laser-precise on the road. And it sounds glorious,
| especially with sport exhaust.
|
| I'm often driving between 20-35 mph in second gear
| because it's the best day-to-day way to hear the engine's
| sounds.
|
| Otherwise, there are people out there buying 911s/etc.
| because they can rather than because they care, and those
| people don't care that Porsche is moving sports cars to
| hybrid, or less interested in putting manuals in their
| cars.
|
| But lots of us still want the pure sports experience.
| brookst wrote:
| Unfortunately, EV's are incredibly heavy, so "faster" is
| scoped to straight lines. As soon as you try to wrestle
| the 2300kg Taycan through twisties, the 1500kg 911 gets
| faster. And it's still massively overweight compared to
| proper sports cars (the 911 is a GT).
| okdood64 wrote:
| Serious [sports] car enthusiasts don't care about faster;
| especially not in a straight line.
|
| I by no means fall into this category completely, but I
| much rather have a moderately slower car than an
| electric, with real engine/intake/exhaust noise that
| handles well on turns.
| D-Coder wrote:
| I have never based a car purchasing decision on how much
| noise the car makes.
| jasonwatkinspdx wrote:
| Your understanding is _very_ out of date.
|
| All electric sports cars have been a thing for a while,
| even at the supercar level. Car enthusiasts have in fact
| embraced electrics. Go on youtube and look up drag race
| comparison races and a Model S Plaid is very frequently the
| one people want to beat.
|
| Double clutched automatics have taken over h pattern
| manuals.
| mrangle wrote:
| My understanding isn't out of date whatsoever. Your
| understanding is wishcasting.
|
| You citing the appearance of the Model S Plaid at
| "youtube drag races" reflects more of your lack of
| understanding than my own.
|
| The double clutch vs manual debate isn't relevant to the
| one under discussion. Its an interface argument that is
| more niched than ICE vs electric, is specialized to each
| particular car, and each particular use and driving
| preference.
| randerson wrote:
| I actually miss DOS. I could focus on one task for hours
| without being distracted by other apps trying to get my
| attention. There was something raw and engaging about being a
| few layers closer to the hardware without all the bloat. And,
| while I'd never go back to mechanical hard drives, you could
| hear the computer 'thinking'. It was more visceral.
|
| I think it's a great analogy. It's all the little quirks and
| flaws that make ICE cars feel like they have a 'soul'. The more
| you have to engage with it, the more it feels human and machine
| are having a conversation. Many car enthusiasts seek out manual
| gearboxes (despite being slower to 60mph than a modern auto),
| because it's _fun_ and gives you some mechanical sympathy.
|
| I own an EV, which is a fantastic daily, and a 911 for
| weekends. I've never felt like taking the EV out for no reason
| other than to enjoy a mountain pass. It's too heavy in the
| corners and too sterile.
| kopirgan wrote:
| Interesting perspective from someone that owns both. I only
| know ICE unless as passenger.
|
| Yes manual steering and gearbox are fun. The response is
| linear predictable.
|
| But if I were a kid entering college I'll be scared to choose
| automotive engineering as it's mostly likely to be wasted
| knowledge..
| kleiba wrote:
| In Germany, where Porsche is from, sales of EVs are on the
| decline. The same is true for other countries in Europe as
| well.
|
| https://www.teslarati.com/electric-vehicle-eu-sales-drop/
| kopirgan wrote:
| Think this is short term. Again no expert just based on what
| I see. Solid batteries give it few years then the maths will
| be very different
| kleiba wrote:
| Not sure. Germans are traditionally both tech xenophobes
| and cheapskates - two arguments against EVs.
| generic92034 wrote:
| Regarding "cheapskates" - I think you have to see the EV
| prices in combination with typical German salaries. If a
| middle-class EV costs more than the yearly gross income
| of an average German software dev, you know there is not
| much room for rising sales figures. Especially figuring
| in the large difference between gross and net income
| here. Add the lacking charging infrastructure and the
| current decline in sales is no surprise at all.
| meiraleal wrote:
| In August. After a 38% tariff.
| kleiba wrote:
| Check out the diagram at the top of this article: https://w
| ww.autozeitung.de/assets/styles/article_image/publi...
|
| As you can see, compared to 2023, the sales numbers have
| been worse month for month in 2024, not just in August.
| typon wrote:
| This says less about consumer habits than about thr quality
| of EVs being sold in Europe and North America
| kleiba wrote:
| The main reason is price.
| _DeadFred_ wrote:
| I think it's more like every keyboard player still lusting
| after physical analog synths even though everyone has perfectly
| usable, deterministic, digitally perfect software synths for a
| fraction of the price (or even the amazing free version of
| Vital).
|
| We are talking hobbyists not corporate office software users.
| ICE is boring to my monkey brain looking to be
| entertained/engaged even if vastly superior.
| ryukoposting wrote:
| There's another block of folks who look at Tesla like a company
| who's making great software in 1994, but it only runs on
| Windows NT.
|
| Yes, EVs are better in a lot of ways, but in 2024 there are
| severe barriers that make EVs impractical for a lot of people.
| Throughout most of the world, charging infrastructure just
| isn't good enough.
|
| Because cities have better charging infra than rural areas, EVs
| are at their best as commuter cars. Ironically, there was
| already an alternative to commuter cars that's hypothetically
| even better than EVs - public transit - and it _also_ suffers
| due to lack of investment in infrastructure development.
| adrian_b wrote:
| The number of the Porsche patent application:
|
| 20240301817
|
| (which can be used on various sites, e.g. https://pat2pdf.org/ to
| retrieve the document)
| jtxt wrote:
| https://ppubs.uspto.gov/dirsearch-public/print/downloadBasic...
| o
| ralfd wrote:
| { "message": "Too many requests" }
| rikthevik wrote:
| If I remember correctly the engine in the Mazda Millenia was a
| Miller cycle engine and did something unconventional like this.
| Props to Mazda for trying new stuff.
|
| https://en.wikipedia.org/wiki/Mazda_Millenia
| Ccecil wrote:
| Miller cycle (IIRC) was a bit different. It simply kept the
| intake valves open longer and used boost from it's supercharger
| to emulate a valve "closing". It used a boost level that was
| significantly higher than a supercharged Otto cycle would use.
| Volkswagen is doing something similar with the EA888.3B (B
| cycle) motor that is in the most recent Tiguans.
| https://www.motortrend.com/features/inside-volkswagen-ea888-...
|
| This six stroke is doing something a bit more complex...more
| impressive, IMHO. Similar in complexity to what Nissan is doing
| with their variable compression engine they are currently using
| https://www.nissan-global.com/EN/INNOVATION/TECHNOLOGY/ARCHI...
|
| There was also a 6 stroke diesel a while back that injected
| water into the empty cylinder after the exhaust stroke to gain
| an extra compression stroke from waste heat...Bruce Crower
| (Crower Cams fame) built one years ago but I never heard
| anything more about it.
| https://www.autoweek.com/news/a2063201/inside-bruce-crowers-...
| addaon wrote:
| Note that the motortrend link you give says that the Miller
| cycle "closes the intake valves much earlier." I'm just
| reading about this for the first time, but this is exactly
| the opposite of the description on Wikipedia [0], and from a
| quick glance at the patent Wikipedia is correct, and
| motortrend is exactly wrong here.
|
| [0] https://en.wikipedia.org/wiki/Miller_cycle
| Ccecil wrote:
| Good note...especially since I misspoke. Apparently..it
| doesn't use standard Miller cycle.
|
| They are calling it Budack cycle.
| https://alexsautohaus.com/whats-changed-with-volkswagens-
| new...
| jeffbee wrote:
| Mazda has marketed half a dozen weird engines, all of which
| were crap. It has been a remarkable streak of stubborn,
| unwanted innovation from such a small carmaker.
| osigurdson wrote:
| I'm sure one day we will look back and laugh about how we used to
| install actual mobile power plants in our cars. But as of today,
| they are still objectively better on many criteria.
| martinky24 wrote:
| What makes you so sure? We don't look back and laugh at people
| using horses for transportation. We understand that's what they
| had at the time.
| osigurdson wrote:
| It personally strikes me as a little humorous, particularly
| from the perspective of a human in (say) 2150. But, not in a
| mean spirited way. Of course, much respect for the pioneers
| of the ICE engine and on-going improvements today.
| jeffreyrogers wrote:
| I thought the nuclear powered aircraft concepts were very cool.
| None every flew though (as far as we know). Russia claims to
| have a nuclear powered missile.
| markhahn wrote:
| I always wonder about premises in cases like this. a pair of
| compression-power cycles is a nice way to question the usual. has
| anyone gone through all the features of a conventional engine and
| asked: what if there's an alternative?
|
| for instance, what if we're just interested in range-extension?
| can we transform the motion created by combustion into electrical
| power in a clever way? cylinder-solenoid coils?
|
| are poppet valves so great? suppose we have some other mechanism
| to create the motion (solenoids?) or rotating valves? something
| electromagnetic appeals because it gives complete control over
| timing (rather than a crankshaft).
|
| rotary engines are appealing, for the same contrarian reasons.
| but they seem to either have practical problems (wankel) or don't
| seem to be making it to market (peanut-shaped rotors, etc).
|
| if 6 cycles makes sense (presumably in combustion physics), does
| it make any sense to burn in one chamber, then move those
| products to another chamber for some further (potentially
| different) cycle?
|
| would it help if you could ignite from more than a single place?
| multiple plugs sounds like a bit of a pain, but could you
| generate an annular spark? would you want to control the
| location-timing of the combustion front? does rotating-detonation
| have any meaning in this context?
|
| are there ways to reconsider the materials engineering of
| engines? make them dramatically cheaper, lighter? one of the best
| EV arguments is simplicity, but how much of current IC
| engineering is based on assumptions that can be broken?
| ithkuil wrote:
| Iirc Koenigsegg is using camless valves (using solenoids?)
| cr125rider wrote:
| Christian and his team over there are actually pushing
| boundaries and doing really cool stuff.
| Too wrote:
| Freevalve yes.
|
| They've got loads of other cool thinking outside of the box
| solutions. Like the Lightspeed transmission with 7 clutches,
| providing instant shifting between any gears and ability to
| slip freely between them.
| elromulous wrote:
| This guy created a hobbyist version. Very impressive.
|
| https://youtu.be/E9KJ_f7REGw?si=hlMQIA9wNkQBniDX
| mpol wrote:
| Since hybrids are now so popular, rethinking how a gasoline
| engine fits into that picture might be worth it. Question is
| whether the market will shift again from hybrids to full EV,
| and if so, when. Designing and building a new engine might cost
| 5 billion, without a real certainty you will earn it back.
| DriftRegion wrote:
| The Obrist Zero Vibration Generator is exactly that:
| reimagining ICE tailored to series hybrid application.
|
| https://m.youtube.com/watch?v=0s5Du7qrPoM
|
| https://www.obrist.at/powertrain/components/
| kevin_thibedeau wrote:
| BEVs will never take over in North America. There are too
| many people spread out or living in places with no hope of
| charging infrastructure. People are going to balk when they
| find out they can only charge from a 20A circuit if even that
| is available.
| jjtheblunt wrote:
| who/what can only charge from a 20A circuit?
| cyberax wrote:
| Lol.
| philistine wrote:
| So North America is limited to its large places? New York
| isn't in North America.
|
| The last mile problem doesn't negate the fact that for 85%
| of people an electric vehicle is possible in five years.
| kevin_thibedeau wrote:
| New York is mostly a semi-rural state where long distance
| travel in a BEV is a problem. One city where most
| residents don't drive doesn't mean anything.
| 01HNNWZ0MV43FF wrote:
| Cylinder solenoids are indeed a thing
|
| https://en.m.wikipedia.org/wiki/Free-piston_engine
|
| And the Prius uses the Atkinson cycle which is slightly
| different from the traditional Otto cycle somehow, although I
| couldn't find a good explanation
|
| https://en.m.wikipedia.org/wiki/Atkinson_cycle
| vvillena wrote:
| According to that Wikipedia article, the modern Atkinson
| cycle trades time spent creating power in the compression
| phase for time spent extracting energy during the expansion
| phase, gaining efficiency at the cost of total power.
| dotancohen wrote:
| > creating power in the compression phase
|
| Other than the potential energy of either the heat or the
| compressed gas, what "power" is created in the compression
| phase of a normal four stroke ICE?
| bestham wrote:
| Pumping losses are greater in a Otto cycle engine due to
| the increased resistance in compressing the whole stroke.
| In an Atkinson-cycle you get a longer power stoke than
| compression stroke and thus are more efficient. There is
| always another cylinder that get does i take during the
| short time when valve is open during compression in
| another cylinder. Thus that cylinder get some free
| assistance during intake.
| ryukoposting wrote:
| Rotating valves exist - look up "spool valves." Much like
| rotary engines, seal wear is the main drawback. Poppet valves
| also have the upside that they inherently spread air-fuel
| mixture out laterally.
| outside1234 wrote:
| Reading these articles is like when you used to read articles in
| 2005 about people "innovating" on OS/2.
|
| The market has moved to electric (see China) and Porsche would be
| well served on investing there versus on OS/2 (nee ICE engines).
| bluGill wrote:
| While you are onithe right track, the market may not be moving
| quite that fast and to a small amount of ice inventment may be
| needed.
| _DeadFred_ wrote:
| It's all in a weird state. Tweaking ICE engines was a fun hobby
| with lots of 'consume' products to dream about. Electric just
| out of the box stomps ICE, but not in the same 'acquiring
| things and putting together a puzzle' type way that feeds our
| monkey brains.
|
| That said Porsche is dead and the super wide Audi's pretending
| to be Porsches just because they have a Porsche skin are lame.
| m463 wrote:
| There was quite an overlap between the use of bows and guns.
| Bows were reliable, accurate, quiet, would work in the rain and
| reloaded quickly. Guns took a long time to exceed them.
|
| I think there is still quite a bit of time left for internal
| combustion engines.
|
| Long distance is a big one, as is racing. Fuel is lightweight
| and can still be added quickly.
| akira2501 wrote:
| > The market has moved to electric
|
| It has not.
|
| > (see China)
|
| Understand the impact of subsidies.
|
| > versus on OS/2 (nee ICE engines).
|
| There is no roadmap to an electric plane in your lifetime. ICE
| engines are going to be here longer than you are.
| Too wrote:
| They do have one of the better EVs on the market.
| johnea wrote:
| That is brilliant!
|
| As soon as they release one with a coal fired steam engine, I'm
| onboard!
|
| Nothing like last millenniums technology today...
| adrianmonk wrote:
| > _To do this, Porsche 's patent shows a crankshaft spinning on a
| ring with two concentric circles--an annulus._ ... _this engine
| has two top and bottom dead centers._
|
| Instead of doing this complicated crankshaft, I wonder if you
| could do this with opposed pistons. The difference between the
| two top dead centers (and bottom dead centers) is small, so the
| secondary piston wouldn't have to move far to create the same
| change in volume.
|
| I can see some advantages and disadvantages. The crankshaft gets
| simpler, but you need to move the secondary piston somehow,
| presumably off the camshaft? Which sounds pretty rough on the
| timing chain. Also, it would have to go where the valves
| currently are. And another piston ring to wear out.
|
| On the other hand, the crankshaft gets simpler, and it's a
| critical component since it's transmitting all the engine power.
| Also, with the opposing piston, you could use a cam to get
| greater control of exactly when the volume changes happen.
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