OT - The inverted Wankel Engine - OT

Botch · July 10

https://www.militarytimes.com/news/2018/06/19/quieter-military-drones-that-fly-farther-the-pentagon-thinks-this-engine-could-be-the-answer/?utm_source=Sailthru&utm_medium=email&utm_campaign=ebb%206-20&utm_term=Editorial%20-%20Early%20Bird%20Brief

Okay, this thread is for uber-geeks and engineers only. Even with videos, I only kinda-sorta-maybe understand how Wankel engines work, and have no idea how a human mind could've come up with the concept, even with chemical enhancement. Well, someone has developed an "inverted" version, which increases efficiency and negates a few of the Wankel's problems. Check out the third video above (the first two are tire commercials), damn.

SamIAm2 · July 10

Title reminded me of this old 1973 TV commercial:

lousubcap · July 10

I am too old to qualify for the "uber-geeks and engineers" classification but because of that I also recall when the Wankel rotary was introduced by Mazda. 'What goes around comes around" seems at play here. Smart people with a focus on eliminating the perceived downsides of 5 decades ago. Good for them.

Grillinois · July 10

Isn’t that in the Kama Sutra?

Theophan · July 10

I had a Mazda RX-7 convertible back in the late '80s and early '90s, and I loved it, and it had a rotary (Wankel) engine. It was a great car.

Botch · July 10

Theophan said:

I had a Mazda RX-7 convertible back in the late '80s and early '90s, and I loved it, and it had a rotary (Wankel) engine. It was a great car.

It came in a convertible?!? I came so close to buying one myself, but needed space for a couple keyboards and an amp in those days...

mEGG_My_Day · July 10

Theophan said:

I had a Mazda RX-7 convertible back in the late '80s and early '90s, and I loved it, and it had a rotary (Wankel) engine. It was a great car.

I had a ‘78 model way back in my he day - fun car to drive

RRP · July 10

I was one of the early believers in the Wankel engine and bought 2 RX-7 brand new.
Both cars were fuel mizers, but would accelerate like a dream!

nolaegghead · July 10

RRP said:

I was one of the early believers in the Wankel engine and bought 2 RX-7 brand new.
Both cars were fuel mizers, but would accelerate like a dream!

I had one and it guzzled gas and the cat-back would literally set the ground on fire.

Botch · July 10

RRP said:

I was one of the early believers in the Wankel engine and bought 2 RX-7 brand new.
Both cars were fuel mizers, but would accelerate like a dream!

They used a lot of oil too, didn't they?

nolaegghead · July 10

they have an oil injection system

Theophan · July 10

Botch said:
It came in a convertible?!? I came so close to buying one myself, but needed space for a couple keyboards and an amp in those days...

I think the convertible was brand-new, had just been introduced when I was looking for a 2-seater sports car to replace my beloved Harley Davidson Softtail that I had to give up because of an inner ear condition that makes me dizzy, sometimes (it's really not good to have the whole world suddenly go off-kilter when riding a two-wheeled vehicle!), I think it was 1988. It was hot red, and a LOT of fun to drive! But no, no back seat, not much of a trunk, really, so no room for musical equipment...

Gulfcoastguy · July 10

One of these in a larger size could be a great engine for a Chevy Volt or similar car. It will never happen though since it burns diesel. That is politically impossible.

Ozzie_Isaac · July 10

I want Merlin in my hotrod.

nolaegghead · July 10

Gulfcoastguy said:

One of these in a larger size could be a great engine for a Chevy Volt or similar car. It will never happen though since it burns diesel. That is politically impossible.

What does diesel have to do with politics? Answer, nothing. But you're probably thinking about the sulfur content, which has been reduced through regulation through the years because diesel fuel, unprocessed, typically has a lot of sulfur in it, which goes through the exhaust, reacts with water and forms sulfuric acid, which kills damn near everything, including people's roofs. Political my ass.

nolaegghead · July 10

The apex and rotor seals were a huge problem with wankel engines. They had to be over-lubricated (thus the oil-injection). Sounds like they resolved some of the issues here, and since the application is a plane, Wankels naturally do better at high-rpm duty. The low and variable rpm in automotive application cause apex seal lifting, and leaking of combustion gas into other chambers, which lowers efficiency and causes a host of other problems.

Efficiency and reliability (from apex seal failure) ultimately hobbled the wankel in cars. Interesting to see what this new diesel design does. Reading the article, it seems to be a good candidate for electrical generation in hybrids. Or is that (hybrids) "political"?

Ozzie_Isaac · July 10

nolaegghead said:

Gulfcoastguy said:

One of these in a larger size could be a great engine for a Chevy Volt or similar car. It will never happen though since it burns diesel. That is politically impossible.

What does diesel have to do with politics? Answer, nothing. But you're probably thinking about the sulfur content, which has been reduced through regulation through the years because diesel fuel, unprocessed, typically has a lot of sulfur in it, which goes through the exhaust, reacts with water and forms sulfuric acid, which kills damn near everything, including people's roofs. Political my ass.

NOx emission requirements is what makes diesels hard to make these days. Tier 4 requirements means almost zero NOx. There is not a cheap low maintenance solution to that.

We used to joke that if we sold Tier 4 equipment to China, we actually be leaving the air cleaner at the exhaust than the intake.

nolaegghead · July 10

Ozzie_Isaac said:

nolaegghead said:

Gulfcoastguy said:

One of these in a larger size could be a great engine for a Chevy Volt or similar car. It will never happen though since it burns diesel. That is politically impossible.

What does diesel have to do with politics? Answer, nothing. But you're probably thinking about the sulfur content, which has been reduced through regulation through the years because diesel fuel, unprocessed, typically has a lot of sulfur in it, which goes through the exhaust, reacts with water and forms sulfuric acid, which kills damn near everything, including people's roofs. Political my ass.

NOx emission requirements is what makes diesels hard to make these days. Tier 4 requirements means almost zero NOx. There is not a cheap low maintenance solution to that.

We used to joke that if we sold Tier 4 equipment to China, we actually be leaving the air cleaner at the exhaust than the intake.

Duh. I was talking about fuel specifications. There's no way to convert the sulfur into anything palatable unless alchemy actually works. The nitrogen oxides are nitrogen and oxygen, which is, like 79 and 19% of air. So the problem is making that stuff into air, which you can do with DEF (which is about 1/3 urea (similar to piss) and 2/3 water.

Funny anecdote with Chinese air. Not so funny when you look at it through a reality filter, like the "great" job Scott Pruitt did.

So DEF turns NOx into N2, H2O and CO2: (stole following from wiki, because I'm dum)

DEF is a 32.5% solution of urea, (NH
2)
2CO. When it is injected into the hot exhaust gas stream, the water evaporates and the urea thermally decomposes to form ammonia and isocyanic acid:

(NH
2)
2CO → NH
3 + HNCO

The isocyanic acid hydrolyses to carbon dioxide and ammonia:

HNCO + H2O → CO2 + NH
3

Overall, this is

(NH
2)
2CO + H
2O → 2 NH
3 + CO2

From this point, ammonia, in the presence of oxygen and a catalyst, will reduce nitrogen oxides:[6]

2 NO + 2 NH
3 + 1⁄2 O
2 → 2 N
2 + 3 H2O and

3 NO
2 + 4 NH
3 → 3 1⁄2 N
2 + 6 H2O

The overall reduction of NO
x by urea is:

2 (NH
2)
2CO + 4 NO + O
2 → 4 N
2 + 4 H
2O + 2 CO2 and

2 (NH
2)
2CO + 3 NO
2 → 2 1⁄2 N
2 + 4 H2O + 2 CO2

Gulfcoastguy · July 10

Seeing as I owned a VW diesel, I already knew pretty much all of that. Funny thing , currently unleaded gasoline has a higher sulfur content than diesel does, 50 versus 15 ppm allowed.

nolaegghead · July 10

Gulfcoastguy said:

Seeing as I owned a VW diesel, I already knew pretty much all of that. Funny thing , currently unleaded gasoline has a higher sulfur content than diesel does, 50 versus 15 ppm allowed.

10 ppm average sulfur in gasoline is the current standard, unless that ruling was obliterated by Pruitt, hard to keep up.

Problem with sulfur in gas, in addition to acid rain, is it wrecks the advanced emissions systems, like the catalytic converters, in modern cars. So it's not just pollution, it's costly to consumers when they fail their emissions tests and have to drop a grand to replace their cats. You hear stories about getting "bad gas". That's one of them, although rare from sulfur.

The sulfur is a lubricant in diesels, which is why they didn't clean it up forever, but the emissions controls aren't really affected by it as much as gasoline emissions systems.

nolaegghead · July 10

https://www.epa.gov/gasoline-standards/gasoline-sulfur

Gulfcoastguy · July 10

The tier 2 rule was in effect when I had to sell my VW back.

Ozzie_Isaac · July 10

nolaegghead said:

Ozzie_Isaac said:

nolaegghead said:

Gulfcoastguy said:

One of these in a larger size could be a great engine for a Chevy Volt or similar car. It will never happen though since it burns diesel. That is politically impossible.

What does diesel have to do with politics? Answer, nothing. But you're probably thinking about the sulfur content, which has been reduced through regulation through the years because diesel fuel, unprocessed, typically has a lot of sulfur in it, which goes through the exhaust, reacts with water and forms sulfuric acid, which kills damn near everything, including people's roofs. Political my ass.

NOx emission requirements is what makes diesels hard to make these days. Tier 4 requirements means almost zero NOx. There is not a cheap low maintenance solution to that.

We used to joke that if we sold Tier 4 equipment to China, we actually be leaving the air cleaner at the exhaust than the intake.

Duh. I was talking about fuel specifications. There's no way to convert the sulfur into anything palatable unless alchemy actually works. The nitrogen oxides are nitrogen and oxygen, which is, like 79 and 19% of air. So the problem is making that stuff into air, which you can do with DEF (which is about 1/3 urea (similar to piss) and 2/3 water.

Funny anecdote with Chinese air. Not so funny when you look at it through a reality filter, like the "great" job Scott Pruitt did.

So DEF turns NOx into N2, H2O and CO2: (stole following from wiki, because I'm dum)
DEF is a 32.5% solution of urea, (NH
2)
2CO. When it is injected into the hot exhaust gas stream, the water evaporates and the urea thermally decomposes to form ammonia and isocyanic acid:

(NH
2)
2CO → NH
3 + HNCO

The isocyanic acid hydrolyses to carbon dioxide and ammonia:

HNCO + H2O → CO2 + NH
3

Overall, this is

(NH
2)
2CO + H
2O → 2 NH
3 + CO2

From this point, ammonia, in the presence of oxygen and a catalyst, will reduce nitrogen oxides:[6]

2 NO + 2 NH
3 + 1⁄2 O
2 → 2 N
2 + 3 H2O and
3 NO
2 + 4 NH
3 → 3 1⁄2 N
2 + 6 H2O

The overall reduction of NO
x by urea is:

2 (NH
2)
2CO + 4 NO + O
2 → 4 N
2 + 4 H
2O + 2 CO2 and
2 (NH
2)
2CO + 3 NO
2 → 2 1⁄2 N
2 + 4 H2O + 2 CO2

Running DEF and having to do regen cycles on a DPF are a headache for consumers. It adds a lot of cost and complexity to an already more expensive setup.

I understand the issues with sulfur, just not sure why you made the leap from politics to sulfur. Politics (EPA) hurt diesels with emissions requirements, not sulfur contaminants in the fuel.

Look at the number of on-highway diesel manufacturers for Semis, Coaches, Buses, etc. Not many left.

westernbbq · July 10

My two mercedes 240 Ds run on waste veggie oil.....

Botch · July 10

westernbbq said:

My two mercedes 240 Ds run on waste veggie oil.....

I've always been curious about that; how long does it take you, say per week, to collect that oil? And I'm assuming you get it for free?

HeavyG · July 10

Botch said:

westernbbq said:

My two mercedes 240 Ds run on waste veggie oil.....

I've always been curious about that; how long does it take you, say per week, to collect that oil? And I'm assuming you get it for free?

I had a coworker a decade ago that converted one of his vehicles to run on used kitchen oil. He used to be able to get it for the asking but as the demand for the waste oil grew and people were willing to buy it he ended up reverting back to diesel fuel.

Eoin · July 10

Cars and light vans here are Euro VI now, 2 steps above Euro IV / Tier 4f. You have to have adblue (the stuff nola was on about above) working with a Cat to get NOx down and particulate filters as well. The problem for owners is the complexity - expensive cats, DPFs that clog if you don't do enough highway driving, EGR valves, adblue systems, DMFs that take a pounding from the diesel torque / vibes etc. When it goes wrong, it's expensive. We've handed back VW Euro VI vans on rental because of adblue / cat issues causing management lights and limp home issues.

For 2019 delivery, even our big shunters (mostly Cummins diesel), which are off highway regulations, will be Euro V, needing adblue etc.

Diesel is not a simple and reliable technology any more.

nolaegghead · July 11

No wonder Volkswagen cheated.

RRP · July 11

nolaegghead said:

RRP said:

I was one of the early believers in the Wankel engine and bought 2 RX-7 brand new.
Both cars were fuel mizers, but would accelerate like a dream!

I had one and it guzzled gas and the cat-back would literally set the ground on fire.

Neither of ours did. What you mean about a cat-back is over my head!

RRP · July 11

RRP said:

nolaegghead said:

RRP said:

I was one of the early believers in the Wankel engine and bought 2 RX-7 brand new.
Both cars were fuel mizers, but would accelerate like a dream!

I had one and it guzzled gas and the cat-back would literally set the ground on fire.

Neither of ours did. What you mean about a cat-back is over my head!

I was quite happy with our 2 new RX-7s after a real let down with our previous Datsun 260Z. All 3 had been purchased brand new. When we went in to buy our 3rd RX-7 they wanted $41K even above our trade-in! I said something polite since my wife was there - like F U and the horse you rode in on!

One day later we bought a brand new '95 Corvette for $35K and trade in.

nolaegghead · July 11

@RRP ; So I was a poor college student and bought an old RX7 used. Engine needed a rebuild, leaky seals, guzzled gas. The CAT (catalytic converter) and cat back - everything behind it - mufflers, pipe, etc, would get so hot from the extra fuel burning in it, rather than the engine, it would glow red at night (visible glow on ground) and it would literally set the ground on fire. Typically dry grass would burst into flame.

Loved the car, great, flat torque curve, but sucked gas and cased forest fires.

Didn't have enough money to rebuild engine. But I did love my 260 and 240z cars even more.

Apex seals are a consumable.

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