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Porsche's idea for a six-stroke internal combustion engine

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Re: Porsche's idea for a six-stroke internal combustion engine

#221

Post by randerson »

kopirgan wrote: post #212

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.

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.

Re: Porsche's idea for a six-stroke internal combustion engine

#222

Post by hnlmorg »

locallost wrote: post #192
hnlmorg wrote: post #145

Earlier quoted context omitted.

Did you actually read my comment and the replies? Because most of the replies didn’t even address the points I was making, let alone debunk it. Just like with your post. I never actually made any claims about mileages. However as it happens, I do specifically fall into that uneconomical bracket. That’s why I ended up buying petrol despite wanting an EV. I work from home and thus rarely drive. EV isn’t yet ready for m…

I read it carefully. Your claim was it's not greener for everyone. It is because the additional costs in terms of emissions are paid off in less than 20k miles. This is a little bit more than the average per year. It's possible a car travels less than that during its life span, but it's so small it's irrelevant. That's like saying it makes financial sense playing the lottery just because someone occasionally wins.

> Your claim was it's not greener for everyone.

No, my point was “EVs aren’t all that green either”.

Things are going to improve. But people so often forgot about all the other environmental costs involved with EV.

In an ideal world we’d be using push bikes, but clearly that’s not practical either. However it’s fair to say that this whole transportation debate is a lot more complicated than people like to summarise.

> It is because the additional costs in terms of emissions are paid off in less than 20k miles.

Again, that was never my claim. That’s a strawman argument you’ve constructed.

Re: Porsche's idea for a six-stroke internal combustion engine

#223

Post by mrangle »

bayindirh wrote: post #216
kopirgan wrote: post #212

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.

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.

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.

Re: Porsche's idea for a six-stroke internal combustion engine

#224

Post by i_am_jl »

MrDunham wrote: post #205
i_am_jl wrote: post #201

Earlier quoted context omitted.

>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 lea…

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.

Ah you're right, thank you!

Re: Porsche's idea for a six-stroke internal combustion engine

#225

Post by freeone3000 »

mrangle wrote: post #223
bayindirh wrote: post #216

Earlier quoted context omitted.

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.

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 emul…

>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.

Re: Porsche's idea for a six-stroke internal combustion engine

#226

Post by Ccecil »

rikthevik wrote: post #219

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

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-...

Re: Porsche's idea for a six-stroke internal combustion engine

#227

Post by Ccecil »

yobbo wrote: post #195
teo_zero wrote: post #51

But isn't the chamber full of exhaust at the beginning of the second power stroke? What will burn?

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.

6 stroke diesel prototype.

https://www.autoweek.com/news/a2063201/inside-bruce-crowers-...

edit: Description before link

Re: Porsche's idea for a six-stroke internal combustion engine

#228

Post by i_am_jl »

magicalhippo wrote: post #206
i_am_jl wrote: post #201

Earlier quoted context omitted.

>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 lea…

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 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.

Re: Porsche's idea for a six-stroke internal combustion engine

#229

Post by jasonwatkinspdx »

mrangle wrote: post #223
bayindirh wrote: post #216

Earlier quoted context omitted.

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.

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 emul…

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.

Re: Porsche's idea for a six-stroke internal combustion engine

#230

Post by Ccecil »

i_am_jl wrote: post #228
magicalhippo wrote: post #206

Earlier quoted context omitted.

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 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…

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.

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