A match for the diesel engine?
The end of the road for the internal combustion engine could be further off than some people think, if innovations like this can live up to their publicity claims without being too expensive for mass use.
Nissan Motor Co. will unveil its VC Turbo engine, which uses an efficiency-boosting variable compression ratio system, at the Los Angeles auto show next week, reports North American Energy News.
Shinichi Kiga, the head of Nissan’s gasoline engine project group, told Reuters that the global automaker plans to keep improving the internal combustion engine and that the VC Turbo engine is part of that vision.
On Nov. 28, Nissan will unveil its Infiniti QX50 sport utility vehicle at the LA Auto Show. The luxury SUV engine uses the variable compression ratio system which will boost thermal efficiency to about 40 per cent, as much as twice the level of current gasoline engines available.
Thermal efficiency is the power an engine generates from a unit of fuel. Kiga says his goal is to develop engines for Infiniti and Nissan vehicles that offer thermal efficiency of 50 per cent.
The VC Turbo engine could prove to be a challenge for policy makers looking to encourage the use of electric vehicles.
James Chao, Asia-Pacific chief of consultancy at IHS Markit Automotive told Reuters that advancing ICE technology is “one of the most overlooked trends in the industry.”
He added “These advances beg the question…Are EVs the best solution to the issue of vehicle greenhouse emissions?”
Continued here.
Tallbloke's Talkshop 
Sounds like the C.R. isn’t continuously variable, but quantized. The problem with electronic engine controls has always been sensors and actuators failing (or cable corrosion). What then? Will they be major engine component replacements? What about longevity?
The Wankel was supposed to be the cat’s meow in the 70s. Durability of key cylinder components was the chief failure and efficiency in production models went the other direction. Variable cam dwell time and profile was also attempted.
CAD programs like Solidworks cannot predict durability of the engine as a system. I hope they are on to something here, but such innovations always seem to take a long time to iron out in production.
Roger,
He added “These advances beg the question…Are EVs the best solution to the issue of vehicle greenhouse emissions?”
The best solution is to get the science right and then teach that more CO2 does no harm and does much good.
Stories by Skeptics telling how to reduce emissions does no good, it reinforces the alarmism
Good can only come from increased CO2, that would improve the food supply of the whole earth. Better efficiency is good in its own right, but reduced CO2 does no good.
Alex
Doubling thermal efficiency, that should translate into more miles per gallon around town, but above 30mph aerodynamics are key, but even there we should surely see improved mpg.
In my diesel Octavia on a run I can reliably get 66mpg, in warmer weather mid 70mpg is possible, I have seen 80 mpg three times in 3 years, I pulled over and took a photo the last time I got 80mpg. Most of my mileage is on motorways. Around town I get about 55 mpg.
I’d love to see 100mpg. Maybe a Nissan in two years time when the lease on this one runs out.
So this is a technology for petrol cars. That would allow petrol cars to start to get the torque and mpg that diesel cars get so that would make it easy for regulators to start adding penalty costs to new diesel cars, thus solving their nox problem.
Mazda have an engine working on the same principle but a completely different design. There are two crankshafts (not really but effectively) in the Nissan and the mazda is more conventional. Difficulty was cold starts because they both rely on pressure (diesel principle but using petrol). They solved it with a spark plug ;). Complex engines both and complexity is proportional to unreliability.
J Martin I do not believe that there is a NOX problem with diesels. Diesel engines in the combustion chamber run at lower temperature than petrol engines and in addition the mixture is less lean (ie less air than petrol) and is more difficult to oxidise the nitrogen in the air. I believe it is false information spread by Greens to counter the success of diesel engines in passenger vehicles as opposed to introduction of electric vehicles. Using LPG in a petrol engine results in more NOX than with petrol because of higher temperature, a further step up will be use of compressed or liquid natural gas (methane). Trucks and long distance buses will continue to use diesel engines for a long time. However, there may be an advantage in road trains (as in outback Australia) to have a diesel generator and electric drive in an enlarge drive train as with diesel electric rail locomotives.
cementafriend; believe as you will, but to work well diesels are generally blown and run hot, NOx is a big problem. cooling the exhaust stream as quickly as possible and deradicalization of the exhaust atoms/molecules is of great importance. Cummings Engines has come out with an injection system that adds ammonia to the exhaust stream to quench the NOx reaction…pg
I guess I should point out that NOx is not created by combustion. It is a self catalyzed reaction of O2 & N2 in the super-heated exhaust stream after combustion. As long as the molecules are carrying over 1200F of energy they combine in NONONONONONONO strings that breakup, the longer the strings the darker the plume and the nastier the pollutant…pg
Volkswagen Scandal: Why Is It So Hard to Make Clean Diesel Cars?
2015: The company may have to recall up to 500,000 diesel cars in the United States and 11 million vehicles worldwide because they emit up to 40 times the allowable levels of air pollutants that are called nitrogen oxides (NOx).
. . .
It turns out that diesel engines have an inherent trade-off between power, fuel efficiency and clean emissions, experts said.
“You have power, you have energy, you have emissions: You get to choose two of them”.
. . .
“The temperatures and pressures under which a diesel engine runs the most fuel efficient and the most peppy are also the conditions that will convert the maximum amount of oxygen and nitrogen into NOx”.
. . .
Clearly, the problem of clean diesel engines is extremely challenging, the experts said.
http://www.livescience.com/52284-volkswagen-scandal-clean-diesel-challenges.html
I’m puzzled by the VC promotional video. It says ” less compression more power”.
My understanding was that power and efficiency increase with compression.
For my old Jag each 1 point rise in compression raise power by about 5%.
Also increases fuel use efficiency.
Look at diesels.
Nothing to do with story above, sorry
I thought you may be interested in the piece, it seems like a decent bit of journalism
https://news.sky.com/story/long-read-grenfell-britains-fire-safety-crisis-11146108
[reply] thanks – I commented on this in Suggestions today but give you a h/t in the new post anyway 🙂
I found this on the internet re temperature in the combustion of a diesel engine
“What is the combustion temperature of a diesel engine?
The compression temperature of air is about 500–600 degree Celsius. The compression pressure needs to be high to have efficient combustion to take place and avoid any ignition lag. This high temperature of the air is the reason behind auto ignition and we don’t need any spark plug in diesel engine”.
NOX does not form at these temperatures.
For a 4 stroke petrol engine there are various temperatures given in the range 1200 to 1600C. NOx will definitely form at these high temperatures. If running with LPG the engine needs to be modified with very high temperature material for the inlet and exhaust valves and the spark plugs because the temperature can get upto 1800C which of course results in more NOx
The combustion in a four stroke engine is more like an explosion while in a diesel it is a rapid burn.
Yes NH3 can reduce NOx but in furnaces the way to bring down NOx is to run with less than O.5% O2 and about 0.2% CO Diesel engines that run with the slightest bit of unburnt in the exhaust (ie trace black smoke) will have no NOx.
There are all sorts of regulations on passenger car engines. It is possible EU regulations require catalytic converters in the exhaust. These maybe the cause of some NOx emissions if badly tuned. The fault lies with the regulations which are not suited to diesel engines. Industrial diesel engines such as in ships or power stations do not produce NOx but they may produce SOx depending on the quality of the fuel oil being used.
It is just political green inspired crap about dangerous emissions from diesel engines. The CO emitted by 4-stroke petrol engines is much worse than the emissions from diesel engines. If you don’t believe it run your car in an enclosed garage for a while but make sure some one can rescue you when you collapse.It used to be the favorite way of suicide.
Cementafriend. Yes the hosepipe from the exhaust to the passenger compartment used to be a tried and tested “topping yourself” method.
However CO in the exhaust (pre-cats) was some 3-4% i.e. 30,000-40,000 ppm.
Post- cat you are looking at is 0.2% about 2000 ppm.
Will still get you, Eventually.
You can see the mechanism here: https://www.infinitiusa.com/now/technology/vc-turbo-engine
Max compression ratio is 14:1, low 8:1. In 1970 my old FIAT had 13:1 ratio. Running depended on fuel quality. If I remember correctly my next, a Metro austin was similar. Both behaved like diesels when fuel quality was poor, and there was no way of stopping it. Both kept running after turning off the switch. So it is still lipstick (or pelvic joint – we’re mechanicals) on the same old lady.
An 8:1 reduces emissions but that is tantamount to cheating. My old cultivator is 7:1, to run on kerosene (not ‘the kerosene’, but the mixture/fuel interface in the transfer piping which cannot be sold as a specific fuel) after start.
Reducing emissions by reducing compression is a way of cheating. Measured per volume of exhaust sees a reduction (which at one point got the EU lawyers fooled), but per horsepower it is not since volume of exhaust then increases.
Same fuel can be burnt in dedicated plant at much higher efficiency, and constantly so. Which is not the same as in a vehicle with variable power demand. The best economical use of any fuel may still be via an mechanical/electric interface.
B&T – ‘On August 15, 2016 Nissan Motor Company announced a new variable compression engine that can choose an optimal compression ratio variably between 8:1 and 14:1. That lets the engine adjust moment by moment to torque demands, always maintaining top efficiency. Nissan says that the turbo-charged, 2-liter, four-cylinder VC-T engine averages 27 percent better fuel economy than the 3.5-liter V6 engine it replaces, with comparable power and torque.’
http://en.wikipedia.org/wiki/Compression_ratio#Variable_Compression_Ratio_.28VCR.29_engines
Air pollution target ‘could be met quickly’
27/11/2017
Prof Paul Monks from Leicester University told BBC News: “As a car ages the fraction of primary emissions of NO2 decreases and this has not been accounted for in emission inventories that ‘predict’ the future.
“It is pure luck… but is positive in terms of the way it impacts air pollution.”
http://www.bbc.co.uk/news/science-environment-42141778
NOx is another of those non problems blown out of all proportions by green nutjobs. The emissions from a car engine are in ppb. Like methane in the atmosphere. However, old petrol engines runs cleaner than old diesels and I think that’s the main issue.
My car carries the No1 badge for pollution in france. It’s diesel and clean. Only an electric gets a better rating in france.
@Steven Richards. So, what is your car ? Mine is a 3 yr old Skoda Octavia Greenline diesel. Certainly the most fuel efficient car I’ve ever had.
Saab SVC engine, old stuff this variable compression
See here: https://www.google.com/imgres?imgurl=https://image.slidesharecdn.com/chap5airstandardcycle2010-130703012738-phpapp02/95/thermodynamic-chapter-5-air-standard-cycle-18-638.jpg?cb%3D1372816337&imgrefurl=https://www.slideshare.net/muhdSurahman/thermodynamic-chapter-5-air-standard-cycle&h=479&w=638&tbnid=1OTQajSWpO6V9M:&tbnh=158&tbnw=211&usg=__gidGU8re4NZYMkmcdQ8Gi6w-m1Q%3D&vet=10ahUKEwiPifHa5ODXAhVFKMAKHWq-CYkQ9QEIKzAA..i&docid=_gvLbXVa1HKVTM&client=firefox-b&sa=X&ved=0ahUKEwiPifHa5ODXAhVFKMAKHWq-CYkQ9QEIKzAA
Compression ration dictates efficiency. The rest is ‘cheating’ at the rules.
The SVC project was shelved by General Motors, when it took over Saab Automobile, due to cost.
http://en.wikipedia.org/wiki/Saab_Variable_Compression_engine
Let’s see if Nissan can do any better.
This is the case with ordinary non turbo IC engines. I have had a few old Lancias, They had 9.5:1 , 10.5;1 and 11.5:1 compression engines. The latter was a homolgation car, and thus had a slightly detuned rally engine.
The difference in power on a 1600cc engine between 10.5:1 and 11.5:1 compression engine was about 17 bhp. But the higher compression engine had hotter cams and four 45mm carbs, instead of four 42 mm carbs. My homologation car had about an extra 30 bhp because of bigger valves and a tuned exhaust manifold and the engine was blue printed.
Of course the power characteristic was different. It had more power and more torque, but both were higher up the rev range. It was only at about 5500 rpm that the 11.5:1 compression engine was superior, and it was noticeably less superior in the 3000 to 45000 rpm range. I guess horse for courses.
The principle maybe different with turbo engines which always have a lower compression ratio compared to the old style efficiently tuned IC engine
high compression engines knock when you step on the gas unless you run high test fuel. low compression engines don’t knock with poor fuel but they have reduced performance. the VC drops compression when you step on the gas to avoid knock then raises compression when you are at speed to increase efficiency.
the design looks pretty clean. extra con rods and cam. all well understood.
the actuator will be key. knock sensor would allow engine to adjust depending upon fuel grade and driving style. might rapidly take over industry if performance gains turn out to be real.
it would not take a lot to modify existing engine designs. basically it can bolt on in place of the oil pan without a lot of rework. raise the engine a bit perhaps to accommodate.
the big question would be why it isn’t more common? more hype than benefit?
Diesels operate at high compression but I wonder if there might be some small benefit to diesels as well if they were to use variable compression. Presumably the compression range within which diesels can operate is much smaller.
Kiga [Nissan boss] told Reuters that along with higher power and better fuel efficiency, the VC Turbo system costs thousands of dollars less than a comparable gasoline-electric hybrid car.
He said Nissan may offer a VC Turbo hybrid in the future.
Covering all the bases.
“Research shows that subsidies for vehicle purchases typically benefit the top ten percentile of income distribution,” says Irvine. “This is what we call a regressive policy.”
Read more at: http://phys.org/news/2017-06-reveals-green-incentives-co2-emissions.html
The Green Brigades better look away now….
SUVs are main attraction at L.A. Auto Show
November 29, 2017
A combination of low gas prices, growing millennial families and a host of new models is fueling the SUV boom. As of October, overall U.S. vehicle sales were down 2 percent compared to the same period last year, but SUV sales were up 6 percent, according to Autodata Corp.
Read more at: http://phys.org/news/2017-11-suvs-main-la-auto.html