It looks like you're using an Ad Blocker.

Please white-list or disable in your ad-blocking tool.

Thank you.


Some features of ATS will be disabled while you continue to use an ad-blocker.


Rotary CNG...Why Not? (Save Earth - Solve Energy)

page: 1

log in


posted on Sep, 27 2019 @ 07:12 AM
I don't know whether to put this post in 'Fragile Earth', 'Science & Technology', 'Automotive'...or 'Rant'. It has elements of all of these, so I guess I'll just stick it here for now and if it needs to be moved, well, then so be it.

The Wankel Rotary engine was (and is) a novel invention. It saw all sorts of budding uses in the 70's and 80's, but for various reasons the conventional piston engine prevailed. One of the big reasons the Wankel engine didn't take off better than it did was because of timing and fuel consumption issues. The other reason was emissions (as a result of these fuel consumption issues), but this problem was overcome. However, the fuel economy of the Wankel engine was compromised because of incomplete ignition of the fuel in the combustion chamber when using gasoline. Gasoline doesn't ignite fast enough to burn completely in the combustion cycle of the rotary engine. More on this in a moment. (Automotive)

Wankel Rotary Engine

Now, if you've been watching the news lately, Mazda, one of the original big champions of the Wankel rotary engine, has been hinting at the Wankel making a comeback. Although it looks like the application they're looking at is as a "pony" motor to run a generator on a hybrid electric car, not an actual production car with a Wankel rotary engine. (Science & Technology / Automotive)

So, when you look further into the Wankel rotary engine and the incomplete ignition issue due to gasoline's slow ignition, almost everything you read about jumps immediately to using Hydrogen as a fuel instead of gasoline. Well, Hydrogen is a horrible idea! First of all, Hydrogen is nasty stuff to work with. It's dangerous to transport, extremely difficult to store because of its molecular structure and positively deadly if you get in an accident. Why not use CNG instead? This would resolve the incomplete ignition issue much the same as hydrogen would. (Science & Technology / Automotive)

So my question is this...we have more natural gas in this country than we can ever possibly use. We have thousands of wells which are just capped off all over the country because the prices are so low it doesn't make sense to extract the gas. Why not use Compressed Natural Gas (CNG) with the Wankel rotary engine? CNG has proven to be a viable fuel, we have fleets of vehicles running on CNG all over the country. CNG burns virtually emissions free. Heck, in my CNG work truck the oil would look brand new after 20,000 miles, so good the oil guys would freak out when they saw it! At the consumer level, CNG didn't take off due to lack of availability, but I'm sure the big oil companies had a lot to do with this! (Rant)

If the issue with the Wankel rotary engine is incomplete ignition due to gasoline's slow burn, then why not use CNG? Why jump from gasoline straight to Hydrogen? Why are we skipping CNG? (Conspiracy)

Here's the facts:

- The Wankel rotary engine is more efficient mechanically than a piston engine. (Automotive)
- CNG is a readily available resource (Fragile Earth)
- CNG is a clean burning fuel for the environment (Fragile Earth)
- Hydrogen is also clean burning, but extremely dangerous (Fragile Earth)
- Hydrogen has zero availability to the consumer (Rant)
- CNG is cheaper than gasoline (Rant)

Why is no one developing a Wankel rotary engine to run on CNG

PS - It's "green", it's efficient, it's cheap and it's smart!
edit on 9/27/2019 by Flyingclaydisk because: (no reason given)

posted on Sep, 27 2019 @ 07:47 AM
The Mazda RX7 has a rotary engine, it goes well. There are a few other models that used it too. One problem it does have is with its average life expectancy. The rotary design does not last as long as the more conventional piston design. Maybe with better material science it could last longer.

I don't see any reason why you could not run CNG in a rotary engine.

posted on Sep, 27 2019 @ 07:57 AM
a reply to: Flyingclaydisk

Nitrogen does not burn (nitrogen oxygen reactions are endothermic).

Burning CNG produces CO2 and water (plus some NOx depending on combustion temperatures).

Nothing stops you from using CNG in gasoline engnes. It would be certainly cheaper to convert existing engines than replacing them with Wankels.

The only benefit of a Wankel is its compactness/weight. Which does not matter much for your typical truck/SUV loving US citizen

posted on Sep, 27 2019 @ 08:02 AM
a reply to: moebius

Not suggesting replacing conventional piston engines with Wankels. What I am suggesting is phasing out less efficient piston engines (for certain applications) in favor of CNG fueled Wankel rotaries.

posted on Sep, 27 2019 @ 08:08 AM
Fantastic post/rant save for one typo:
"Why jump from gasoline straight to Nitrogen?"
You what when?

Here's my take on it.
CNG engines work. The bus fleets in town use it.
I've never worked on an engine running it, but it should burn pretty clean. I'm interested to learn more about the motor oil life expectancy.

The wankle engines, though... they're junk.
I mean, sure- they can spin REALLY fast. Which is why gasoline became a problematic fuel for them.
But the design is awful.
It's an ok design if you're trying to, say, turn compressed air into high torque rotation... but honestly, a turbine and a gearbox will last longer.

I've wondered for years why these electric cars don't have gasoline generators in them- a high speed turbine engine could run on pump diesel and generate more electricity than the car could ever want... But maybe that's the point. You'd have to scale the stupid thing down a LOT to size it correctly, otherwise you'd be cold starting it all the time... which defeats the purpose.

posted on Sep, 27 2019 @ 08:10 AM
a reply to: kwakakev

The longevity issues have for the most part been addressed now. The issues were thermal related sealing issues. These have mostly been resolved.

It is true though that the rotary engine does have better life with higher RPMs under load. Where it has issues is with lower RPMs and/or no load. This, frankly, is a good problem to have and one easily addressed. It's akin to saying you can't run fast because your pockets are loaded down with too much money in them.

posted on Sep, 27 2019 @ 08:19 AM
a reply to: lordcomac

"Nitrogen" DOH!! Fixed it, thank you! It's early.

I disagree with the notion the Wankel rotary is "junk". Early evolutions of the Wankel were less than ideal, but many of those issues have been corrected over the years, much the same as issues with early piston engines have been improved. Fundamentally, the Wankel rotary engine is not only sound, it's pure gold. Everything rotating in one direction as opposed to reciprocation alone is a giant leap forward.

I do agree that using a generator application (forget engine type) would be more efficient. Even further to your point, a Wankel powered generator is one of the application probably best fit to a rotary type engine.

edit on 9/27/2019 by Flyingclaydisk because: (no reason given)

posted on Sep, 27 2019 @ 08:29 AM
a reply to: Flyingclaydisk

I don't think any kind of engine burning fossil fuel is the answer.

posted on Sep, 27 2019 @ 08:43 AM
a reply to: lordcomac

I've never worked on an engine running it, but it should burn pretty clean. I'm interested to learn more about the motor oil life expectancy. ...

Well, I can tell you my experience with CNG.

My previous company truck was CNG. We ran two different types of CNG vehicles in our fleet, straight conversions and dual-fuel (switchable). The dual-fuel trucks were dogs and were plagued with starting problems. Just a horrible application. My truck was dedicated CNG and it was fantastic.

My truck was a Dodge V-8 2wd pickup. It got about 19-20 miles to equivalent gallon, and had more than enough power even at high altitude. The oil was the amazing thing. When we had the truck converted (which I'll get to in a moment) the conversion shop said we wouldn't need to change the oil before 7,500 miles (interval). After the first 7,500 miles we took it in and the guys couldn't believe how clean the oil was. It looked like it just came out of the container (seriously)! The oil never fractured, the engine ran SUPER clean and it ran cool. You could easily run one of these engines for 100,000 miles on one oil change if using synthetic oil.

Emissions was another thing. Colorado was weird then so we still had to take the truck in for emissions tests. When we'd get it tested the testing people would all sit there and stare at the results. It would be like .0000000003 when everyone else was testing at .05 ppm (I don't remember the exact values, but that was how wide the difference was). The truck would test at 3,000% UNDER what it took to pass. So, from an emissions standpoint, it was better than any other single car on the road.

Ran it for about 200,000 miles until I cracked the block one day when I had blown a head gasket and didn't know it.

Conversion - the straight conversion process is expensive ($5,000). Dual fuel is much less (around $600). The big difference is, straight conversion changes the compression ratio by changing the heads, and replaces the intake manifold completely. Dual fuel does none of these things because the motor would blow up if you ran it on gasoline, so the compression ratio stays the same and so does the intake manifold / carburetor. They just put an injector into the side of the carburetor. The net result is the dual fuel's have sluggish performance on CNG and serious starting problems in cold temps.

posted on Sep, 27 2019 @ 08:44 AM
a reply to: dfnj2015

So you don't consider the sun a fossil fuel?

And what about those batteries???

posted on Sep, 27 2019 @ 08:45 AM

originally posted by: dfnj2015
a reply to: Flyingclaydisk

I don't think any kind of engine burning fossil fuel is the answer.

Yes and no.
Electric motors run on fossil fuel. They are coal engines.

The best answer in the near future is higher efficiency engines.
Things like solar panels are pretty much maxed out in their abilities.
The best we can hope for is some sort of physics/chemistry breakthrough.

posted on Sep, 27 2019 @ 10:07 AM
Mazdas go.....mmmmmmmmmmm!

I love a the to tax ultralight aircraft engine a rotary....idk. my buddy in North Dallas, steadily does Mazda rx 7 upgrades.....make even

posted on Sep, 27 2019 @ 10:23 AM
I was working on designing a rotary engine that was not a wankle, the engine had valves that actually moved and compressed the gasses and did all the work. The valves could be replaced quickly by unbolting them. I have no way of testing this or building it. It would be fuel efficient and could have a high speed but the torque would not be enough alone to operate a car. It could run a generator that runs electric motors at the wheels though, something not available when I designed it forty years ago. The small engines could be bolted in series together and be the size of a ten inch tube with some valve systems attached to it, one per one foot long engine. It would make a great plane engine. a compression valve body could be replaced in fifteen minutes with a new one and rebuilt.

posted on Sep, 27 2019 @ 02:44 PM
I would go for mandatory turbo charged inline 6 cyl. but that is just me. I could tolerate ethanol but would prefer the 102.

More serious now.. Modern engines recycle some exhaust gases to a certain RPM back into the intake manifold. The Wankel motor principle has its own downsides. It all is depending on the type of usage.

Electric motors, like another member wrote, run on coal/gas/nuclear for a big part.

posted on Sep, 27 2019 @ 03:13 PM
Liquid fuel is the reason the world population was able to explode after the 1800's.
Without cheap energy we'd still be stuck hunting whales for lantern oil in sailboats, and the world population would still be at a reasonable level. Of course as a species we've doomed ourselves with the amazing resource we found... But that's neither here nor there.

Using compressed natural gas? I don't have much experience with it, but I am happy to learn about it. Thank you for sharing what you know about it! I know a guy who briefly worked in a service shop for the city busses that run on CNG, I'll have to ask him for his input next time we meet. I don't even know if those are conversions or purpose built engines.
They're state funded so my guess is they're not only converted, but they were converted at the highest possible cost with the lowest possible reliability.
I mean, you had a dodge- who actually buys a dodge on purpose?
sounds like my tax dollars at work.

I still think turbine engines are probably where its at for electricity generation. So far they're basically only used for jets- but as better bearings get cheaper, making a smaller turbine engines becomes possible. There's that guy who strapped some to his arms to fly around like iron man recently... Dump that energy into a 100lb generator and throw $1000 in chinese electronics at it, you could have a real monster generator capable of running an electric vehicle on high density liquid fuel. I'd love to see the numbers on that vs a prius four stroke...

I guess a turbine would just as happily run on CNG, though, which brings us right back on topic. Who needs oil changes?

posted on Sep, 27 2019 @ 03:13 PM
a reply to: Flyingclaydisk

Saving the earth isn't profitable

posted on Sep, 28 2019 @ 09:38 AM
a reply to: lordcomac

I mean, you had a dodge- who actually buys a dodge on purpose? sounds like my tax dollars at work.

HA! LOL! It's even funnier than that! The "Dodge" actually WAS a government (City) vehicle. Apparently, some City employee was told to bring the truck down to the CNG conversion place and have it converted. He was supposed to have them convert it to dual fuel, but didn't understand the differences. (Frankly, I wouldn't have either). Well, he told them to do a straight conversion on it. When the City saw the bill they couldn't/wouldn't pay for it, so the CNG conversion company wound up with the truck. We actually bought the truck from them. The truck was 3 years old then, but basically brand new. So we got a brand new $19k truck WITH a full CNG conversion for $5k.

And there's even more (funny stuff)...

We were going to be using the truck for use on an airport airfield. Airport regulations said all airfield vehicles had to have a logo of a certain size on both sides of the vehicle. The regs said the logo had to be at least 8" tall (so the Air Traffic Controllers could see it from the tower). We sent the truck to the signage shop to have a logo put on it, but they read the regulations wrong as 18" (not 8"). So when we got it back it had this GIANT logo on the side of it!

The truck kind of wound up becoming a legend at the airport because of its giant logo. What made it even funnier was the logo was a 3 letter acronym which didn't stand for anything, so people would always ask what the letters stood for and we'd have to explain they didn't mean anything. We even had a request sent by the FAA asking what it stood for (so they definitely could see it alright)!

It was a good old truck. I still kind of miss that thing.

new topics

top topics


log in