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

motor1.com

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

#301

Post by magicalhippo »

magicalhippo wrote: post #265
Ccecil wrote: post #230

Earlier quoted context omitted.

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…

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), co…

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

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

#302

Post by randerson »

OJFord wrote: post #246
_yb2s wrote: post #199

Earlier quoted context omitted.

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.

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…

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-porsche-911...

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

#303

Post by Ccecil »

magicalhippo wrote: post #301
magicalhippo wrote: post #265

Earlier quoted context omitted.

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), co…

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. Intak…

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.

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

#304

Post by fragmede »

jvanderbot wrote: post #164
thebruce87m wrote: post #125

Earlier quoted context omitted.

> in my European country electric infrastructure is not ready for electric cars and with current energy prices this makes no financial sense. I’m always amazed by statements like this. People who have lived through the rollout of the internet to the masses can’t see how we’d modify existing structure to accommodate needs. We had phone lines initially, 20 years later now we have 5G, fibre, satellites. They just dug up…

We have two massive parallel energy transfer systems in the world. And they are massive. Consider the electrical grid for all it's behemoth costs and regulations, at least it exists and is a known monster. Doubling it is a technical challenge but not an unknown. Akin to laying fiber. On one side of the grid you could even just change how the energy is produced at a few thousand plants and have zero change on consumer…

In addition to electricity and gasoline, there's also natural gas, which is shipped around in giant tankers and via pipelines, and then piped into homes to be used for heating and cooling in many places. Also for systems we transfer energy around on Earth, consider the infrastructure used to ship coal all around the world, on trains and ships.

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

#305

Post by addaon »

Ccecil wrote: post #226
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-...…

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

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

#306

Post by 123yawaworht456 »

sheepdestroyer wrote: post #26
lb1lf wrote: post #7

Earlier quoted context omitted.

Presumably as Porsche is not about efficient transportation; it is about emotion, driving as an experience, making a statement, etc. Chances are there will be - or, at least, Porsche appears to bet there will be - a sufficient number of well-heeled enthusiasts who prefer the sound, smell and vibration of an ICE to the quiet performance of an electric motor. I am really curious to see how this pans out in a generation…

[flagged]

people who drive expensive cars don't care about twitter opinions.

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

#308

Post by Ccecil »

addaon wrote: post #305
Ccecil wrote: post #226

Earlier quoted context omitted.

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-...…

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

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...

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

#309

Post by vardump »

hnlmorg wrote: post #290
vardump wrote: post #263

Earlier quoted context omitted.

Here seems to be one what the grandparent suggested, an EV with a SIB battery. https://www.electrive.com/2024/01/02/first-sodium-ion-batter...

China specific. So not really mass market. Though I am glad to see that there are cars entering the market with sodium ion batteries. That does give me hope for the long term future of EV.

Wait until 2030'ies. Then you're going to see cheap mass market SIB EVs.

Tuning SIB chemistry and getting enough factory capacity up takes a while.

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

#310

Post by kevin_thibedeau »

philistine wrote: post #298
kevin_thibedeau wrote: post #284

Earlier quoted context omitted.

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.

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.

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.
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