81–90 of 241 posts
Earlier quoted context omitted.
Are those imperial gallons or US gallons?
I can get 40MPG (US) highway with a 2015 Mazda3 and a somewhat aggressive driving style. City is usually low 30s. The manual transmission is also one of the nicest I've ever driven. These are great cars.
Earlier quoted context omitted.
I don't think hybrids have any future except in the heaviest of vehicles, where batteries won't make sense for another few decades. We're already seeing companies being interested in making battery-only buses, tractors, semis, and even airplanes. Not all models of those types of vehicles may work with batteries, but it's a sign of what the future could bring.
Total individual perspective here, but my dad took me on his worksite like 15 years ago to see the big super gorram awesome trucks (seriously those things are HUGE). When I asked about the engines, he said the trucks had massive diesel generators that powered motors, that in turn powered the wheels and hydraulics. So in a way, lots of construction equipment has kind of already been "hybrid."
SKYACTIV-X is the world's first commercial gasoline engine to use compression ignition, in which the fuel-air mixture ignites spontaneously when compressed by the piston. Just pure curiosity, I wonder if SKYACTIV-X engine would also also consume diesel or gasoline/diesel mixtures?
Earlier quoted context omitted.
Yes, however common diesel fuels tend to be higher in NOx and particulates. My understanding is that because gasoline is refined to a higher degree it burns a fair bit cleaner in similar environments(and also makes it a PITA to store for more than a few months). [edit] We've got a pair of tractors around the house here, '81 diesel(pre-emissions), and '47 gasser. I can tell you which one I prefer to run from an exhaus…
NOx emissions from a diesel engine are from atmospheric nitrogen and oxygen, not from the fuel. I welcome further clarifications, but my understanding is that this engine will not produce NOx like a standard diesel because the fuel/air mix will be tightly controlled like in a gasoline engine, and temperature and pressure will be significantly less than a standard diesel. Additionally, it seems the timing of the fuel…
The argument in the linked wikipedia entry is that combustion temperatures are lower in this cycle because the better fuel/air mixing means it can burn much leaner and thus at a lower temperature. But a leaner mixture means lower power for a given displacement too, which means lower efficiency than a comparable traditional diesel (which are already hard-pressed to see gains like the 40% claimed against well-tuned gas engines).
Honestly the whole thing sounds very snake oily to me. I don't deny that it's possible such a thing could be tuned to operate as well as a traditional engine, but... it sounds awfully fiddly. I'd want to see numbers from a production engine in a real car before placing any bets. Electric continues to look like a much better bet to my eyes.
Earlier quoted context omitted.
Rotary is actually a good example for "revolutions" that turned out to be inferior compared to existing solutions. We will see how the new engine will perform in the real world.
Wankel engines work fairly well, but the geometry is so constraining that they can't be improved much. Can't change the shape of the cylinder head. Can't change the valve timing dynamically. That's all fixed by the geometry. They got as good as they were going to get decades ago.
Earlier quoted context omitted.
Or a bet on hybrids. Hybrids enable new types of engines that for instance operate at constant rate or that are under-powered for acceleration from a stop or going uphill.
I bet on plugin hybrids, specifically ones with large batteries. This seems to be an unpopular opinion, but I think the Voltec drivetrain shows what's possible here. Pure EV purists dislike PHEVs because they have the complexity of an ICE car + an EV car, but I think there's some serious advantages. Like you say, Atkinson cycle for electricity generation for when the battery drains beyond smaller commute ranges. Some…
I would imagine most the complaints are for when the ICE actually powers a drivetrain. If it's essentially a generator to keep the batteries from depleting too far, that's not much extra complexity it all. Have a problem with the generator? Just swap it out with a new or rebuilt one from some vendor (if designed well such that you can do so). I'm seeing that a Tesla uses about 300 Watts a mile @ 55 Mph.[1] Honda seems to have generators much more than capable of supplying that need for under $1000.[2] I'm not familiar enough with electric systems to know how accurate that assessment is (whether the voltage requirements complicate it, for example), but that seems promising. Then again, I imagine if it was really that easy, Tesla would have put a generator charge hookup and exhaust ventilation capabilities in the trunk already.
Edit: Hmm, I'm definitely missing something, since the $1000 generator says it can go 8.1 hours on a gallon of gas, and it doesn't seem likely for that to translate into powering a Tesla for 8 hours of travel.
1: https://teslamotorsclub.com/tmc/threads/average-wattage-for-...
2: https://powerequipment.honda.com/generators/selecting-a-gene...
Earlier quoted context omitted.
We have the big and beautiful 280 between Mountain View and San Francisco, and I thank goodness every time I make my way to the city for it. I'd never go the speeds on my bike I do on 280 anywhere else, but it's just such a gosh darn huge road I get to make a 45-60 minute trip in like 30 minutes.
I though you Americans have it pretty rough when you're caught going over speed limit?
SKYACTIV-X is the world's first commercial gasoline engine to use compression ignition, in which the fuel-air mixture ignites spontaneously when compressed by the piston. Just pure curiosity, I wonder if SKYACTIV-X engine would also also consume diesel or gasoline/diesel mixtures?
Almost certainly not, as diesel and gasoline have very different self-ignition properties.
Earlier quoted context omitted.
Gasoline engines aren't going away for a while; even when every self-driving car is electric, there will be a market for people who want gasoline engines. If it gives a bump in fuel economy to the next (last?) generation of gasoline and hybrid vehicles, great! I also wonder if the maintainability of these engines will be the same as with diesel. That would be another big benefit.
> I also wonder if the maintainability of these engines will be the same as with diesel They also include traditional spark plugs and the engine automatically switches between modes. So, I fear that maintenance wise, it may be the worst of both worlds -- but with less wear and tear on the spark side, perhaps it will be better.
Earlier quoted context omitted.
That is horrible mileage. I remember averaging that on a 1997 Opel Astra.
You're trolling, right? 40mpg is pretty great.
Modern small cars with small engines can be quite fuel efficient in highway driving, though, and there 40 mpg isn't quite the very top. A month ago or so I did a trip in a 2016 Seat Toledo (petrol, non-hybrid), and the drive computer reported the consumption as 3.9 L/100 km after 150 km of driving at speeds from 60 to 100 km/h, averaging IIRC 78 km/h.
A 80 km strip at 120 km/h increased the average to 4.2 L/100 km.