It seems to me, that with a world wide switch to electric power, there will be no one interested in spending money to improve ICE.
Right, this. There’s a very simple way of explaining a hard limit on how efficiently a device can convert thermal energy into any other form of energy (such as mechanical or electrical). You convert some thermal energy into another form by letting thermal energy move from a higher temperature to a lower one. We want to use absolute temperatures for the following to be right. If you let thermal energy move from a high temperature to a lower temperature that is only X% of the higher temperature, then at least X% of the original thermal energy has to remain as thermal energy, and at most (100-X)% of the original thermal energy can wind up as some other form of energy.
This hard and fast limit, which I am convinced has something to do with statistical mechanics and randomness, shows why it is really difficult to get much power out of small temperature differences in everyday circumstances.
As a very general principle, I think people dramatically underestimate how much benefit comes from years of optimization. Even if one of these alternative architectures were somewhat better than the traditional one, they didn’t go through 150 years of improvements, with many tens of billions of dollars spent on optimization. If some architecture is 10% or 20% better, in principle… well, there’s no way that a small team building such a device could overcome all of the other factors.
Disruptive technologies do happen, but they typically have to be multiple factors better than the “establishment” to have any chance at succeeding. And that’s not possible for ICE efficiency due to thermodynamics. Even absolute perfection gets you less than a factor of 2.
In some fairness to the original SBC 350, in the earlier years when it was allowed to run wild, it made much much more than 170 HP. ( it should be noted that in the Camaro, 1975 was the nadir with 155 HP. It was absolutely strangled.
1971 was a year when gross and net HP numbers were published, and in the case of the LT-1 350, it was 330 HP gross, and 275 net. Using this I calculate the difference that net as equipped in that car as 16.5 percent. Use that against the 1970 model year LT-1 of 360 HP in the Camaro, 370 in the Corvette gives us 301 or 309 HP net ( and the ability to mod it to much much higher power levels ), for an apples to apples comparison.
The nice difference in the technology today is that while we can produce big power, bigger than many of old in their halcyon days, they can do so with much more efficiency, even in larger displacement engines.
And still pass US emissions standards? A 3 liter Ferrari could make 240 hp, but it cost a whole lot more.
The supposed “world wide switch to electric power” is going to be the work of several decades, and there are still going to be niche applications where mobile power generated by combustion engines of some form will be necessary (specifically aircraft and heavy shipping), as well as the fact that most electrical power production besides PV solar, wind, and tidal are via heat engines in some form.
Stranger
Of course, but the point is that the investment dollars won’t be there. Vacuum tubes are still used, and could be much better and cheaper than they are–but there aren’t billions in development dollars available. So the technology is stagnant.
Automakers are already gutting their ICE divisions. It won’t be long before ICEs for light vehicles are essentially frozen in their current state. They’ll still be used for some things, but they won’t get better. They’ll probably get a little worse, in fact.
Long-haul aircraft engines probably have a few more decades of development life in them.
The aero engine manufacturers are deep into the development of the first generation of hybrid turbo-electric engines.
They admit there’s not a lot of room to further optimize the basic high-bypass turbofan introduced in 1969 by the 747. Geared fans and ever-greater bypass ratios are nearing the turbine equivalent of Moore’s law hitting the quantum feature size limit. That truth is sinking in everywhere. That well ain’t quite dry, but it’s suckin’ mud.
Hybrid electrics, and “bottoming cycles” to recover waste heat into useful work are the next Big Thing for transport engines. In the high performance fighter / attack market the 3-stream variable fan engine is coming right along. Just bring money.
Higher operating temps: back in the 60s, thermostats were in the 160-180 deg F range.
I had a 90s era Honda Civic with a 195 deg thermostat.
A hotter engine is a more efficient engine.
What are the high-level benefits of these? I understand hybrid cars: you get kinetic energy recovery, and an engine that can be smaller and run within a tighter power band. What are the benefits for turbines?
In general turbine engines are most thermodynamically efficient when run flat out. Part of the long climbs in jets is about climbing to an altitude where full engine power (and hence max miles per fuel unit) is just enough to maintain cruise speed. The fact higher altitudes mean greater speed for the same drag and therefore greater per-day productivity from teh machine is gravy. Essential gravy, but gravy nevertheless.
Particularly for engine failure scenarios on twin-engine airplanes that means the engines are oversized for normal use to be big enough to be able to step up in a failure scenario.
The thought is to use a relatively small peaking battery and embedded electric motor to provide the extra HP/torque to the fan shaft needed for normal takeoff and failure takeoff scenarios, cutting back to pure turbine operation for most of the flight, while recharging the battery for similar use on the next takeoff.
In an interesting parallel, the vertical tail is also sized to manage the takeoff engine failure scenario. Which places huge demands on adequate control power to keep the airplane going straight with wildly asymmetrical thrust at low speed. Major efforts are underway to increase the aerodynamic maneuvering power of the tail such that it can be much smaller and therefore less draggy for the 99.9% condition of normal flight, but still deliver in a pinch.
How about a tailrotor, like a helicopter? Just make it electric. I’m only, like, 93% joking here…
Thanks for the info. I guess it is ultimately the same design principles at play, except that aircraft engines are sized for climb (and engine out scenarios), while car engines have to be sized for decent acceleration from a stop.
Well, some are. However, even if the developed world goes full tilt on producing electric vehicles there are supply limitations for both the batteries and motors, and the developing world doesn’t have the infrastructure to support reliable mass electrification and will be using some version of internal combustion engine for the foreseeable future, possibly switching to second generation biofuels, syngas-based fuels, dimethyl ether, et cetera. And I’ll maintain that even as electrification make take over commuter markets and (perhaps) long haul OTR transportation, there are going to be numerous applications where the ability to fuel a vehicle instead of having access to the power grid are going to continue to require some kind of combustion engine. Internal combustion engines certainly aren’t going to “get a little worse”, and with certain fuels there is actually an opportunity for better thermodynamic efficiency even if the mass density of the fuel is inferior to gasoline or diesel.
It’s actually not a bad idea although complicated, and you can see from recent uncrewed aircraft that a true aerodynamically unstable aircraft with no tail surfaces, just using some combination of ailerons and vectored thrust to maintain yaw stability. A Conda-effect tail boom driven by an electric blower could certainly be used to minimize drag and would probably even be pretty efficient. However, commercial aircraft are very conservative in design and I doubt you’ll see anything like that in the foreseeable future.
Stranger
That’s probably true, but the market is not large enough or profitable enough to drive the investment that is needed to design and build new ICEs for cars.
ICEs for plant and machinery are a different matter. Although some manufacturers are introducing electric versions, mainly for use where noise and/or pollution is restricted, the multi-fuel (diesel/vegetable oil/hydrogen/?) engine will remain king for the foreseeable future _ possibly as hybrids, but much of that market requires ease of maintenance and simplicity.
GM is investing nearly a billion dollars into its next generation V-8.
Honda tried oval pistons in a motorcycle engine some years ago.
According to a video I found, the idea was to build a four-stroke racing engine that could compete with the two-stroke engines of the day. The oval pistons meant they could have 8 valves per cylinder. They still didn’t get to quite the rev limit that they wanted, and the engine only won two races in four years. There was a road-going version as well, but it was ridiculously expensive.
A dead end, but I give them credit for trying something new.
Honda were working on an oval cylindered F1 engine as well apparently. But it was banned before it saw the light of day. This was at a time when Honda were the pre-eminent engine manufacturer in F1, and the arms race that might have arisen was too much for the FIA to stomach. No doubt Ferrari had a word in the FIA’s ear as well.
GM clearly expects the current obsession of American men who express their masculinity by driving large rugged vehicles, even though they never go off-road and mostly use them for commuting to continue indefinitely.
There will likely be a market in Africa too and, maybe, S America. Western Europe is going hell-for-leather down the electric route. By 2030 you will not be able to buy a new ICE car in most of Europe. Legislation to prevent imports of used models will probably follow.
There are any number of technological advances that could improve power density and or efficiency, but in most cases they’re limited by one of the other critical constraints:
- cost
- durability
- emissions
Example, F1 and IndyCar drivers can adjust their air/fuel ratio anywhere from slightly rich for max power to rather lean for best fuel economy. OTOH, the gasoline spark-ignited engine in your car runs with a stoichiometric mixture (just enough air to complete oxidize all the fuel, and no more). Just like those race cars, you could get better fuel economy if you were allowed to operate it with a lean mixture, but then the emissions control system wouldn’t work well at all; tailpipe NOx emissions would skyrocket.
Oval cylinder bores are much harder to make and hone than round bores. It’s also harder to make oval pistons and oval piston rings. So right away, this engine’s gonna be more expensive than one with round bores, and for a breathing/power density improvement that really only shows up when the driver puts their foot to the floor and winds up to high RPM. Oval rings and bores also likely don’t seal as well as round ones, which means more blow-by of unburned (and burned) mixture into the crankcase, aging the oil more rapidly. And a larger crevice volume between the piston crown and the bore means more fugitive mixture hiding there during combustion, only to be released unburned back into the combustion chamber later in the power stroke and expelled as increased hydrocarbon emissions in the tailpipe. These kinds of things don’t matter when you’re trying to win a race, but when you’re trying to mass-produce an emissions-compliant car for a lower selling price than your competitor, they’re showstoppers.
I recall some comments at the time that Honda was doing it mostly to prove that they could. It would be an example of their engineering and manufacturing superiority and they didn’t expect real improvements. This was over 40 years ago, that may be a baseless opinion, but at the time they were showing engineering and manufacturing dominance in the auto and motorcycle industry and technological superiority was used as a marketing point in at least the motorcycle market at the time, so I think that pride was actually a factor. IIRC they were a leader in ultra-high RPM motorcycle engines also around that time.