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Quote Thomas Pederson: "cujet, Why on Earth would you keep the foot on the gas coming up to a stop where you know you have to brake?!? The only thing gained from that is higher fuel consumption and more brake wear." For practical reasons, that's why. On urban surface streets, coasting from a "hypermile" speed of 42MPH to zero, timed exactly to recover 100% of the energy takes time. With much of that time spent slowing to a crawl, often in neutral with engine off. VW TDI cars on LRR tires coast like crazy. Hypermile driving is fun, when nobody is being inconvenienced. This is not the case here. The last thing I want to do is intentionally annoy my fellow Americans. That's simply rude and inconsiderate of their needs and wants.
Quote: "Gerdes is an expert hypermiler". Enough said. It's not just the car, it's the annoying driver. There is no way that car kept up with traffic. Hypermile driving is so incredibly annoying to others. It's fine if alone on the road, but not in daily traffic. Hypermilers typically cruise at the most efficient speed (read 42 MPH) and "lift" throttle and even shut the engine off, 3200 to 3700 feet before every stop. They are annoying beyond belief.
OK, I can see this when you compare a diesel Jetta to a gas Jetta. I owned a 2006 Jetta TDI for 70,000 miles+, and I enjoyed driving the car. The poor reliability was the only reason I sold it. Even so, the private resale was not horrible. I sold it for 1/2 what I paid for it. However, if you compare a Prius (a similarly capable car with equal interior room) to the Jetta TDI, I'll bet a dollar, the Prius costs less to own. Not to mention far superior reliability.
Fantastic. Toyota has just achieved 44% thermal efficiency. The exact same thermal efficiency my 1930's designed Lister CS diesel achieves at it's peak. Of course, the Lister CS uses a cast iron piston, chrome plated bore and cast iron cylinder head. This results in less combustion heat rejection than similar aluminum parts.
I'm missing something obvious here. Why have an intercooler and a recuperator? Is the idea to simply cool off the compressed air, then use waste exhaust heat to re-heat it prior to combustion? I don't follow the logic.
So a downsized engine and battery energy is where fuel savings comes from. That's not a real savings, as energy needs to be put into the battery pack before each climb or takeoff. Also, there is something missing in the youtube video. The fact that piston powered, non turbocharged aircraft with constant speed props often don't get throttled back at typical cruise altitudes. As the altitude related HP loss typically matches the aerodynamic drag decrease at higher altitudes. What normally happens is the RPM is reduced slightly, from 2700 to 2400-2500 depending on aircraft model and engine/prop type. The main reason a fixed pitch prop equipped aircraft gets throttled back, once at cruise altitude, is to avoid too much RPM.
A properly constructed aluminum body will last nearly forever. My Cessna aircraft is now 45 years old and still in excellent shape.
From a practical standpoint, most consumers don't want to pay too much for a car. It really is that simple. I'd love a Volt or Tesla. When the Volt first came out, I drove it, loved it, and looked into purchase. Financing $50,000 for what is in essence, a compact car, made zero sense. Even with the incentive. I'd still be subject to a massive car payment. $1041 per month, zero down, 0% interest rate, 48 months. NO THANK YOU> I'll purchase 3ea. Toyota Yaris, or 2ea. Toyota Prius.
Bob tasa, I am inclined to disagree with a number of your points. First, the Volt is a battery/gas vehicle. Turbocharging a smaller engine with electric (or conventional) turbo's does not result in stunning MPG. Yes, it's a small help, under some conditions, but BSFC numbers don't improve to the 100MPGe range as it does via efficient battery-electric drive. I also don't understand your "step sideways" comment. It promises to be a more refined drivetrain. What's not to like about refinement? Or more efficient operation, or better battery range? Finally, compared to the cars I drive, the Volt is not/does not look "cheap" or low "quality" in any way. Not all of us can afford expensive vehicles, oozing with hand stitched leather, 40 series tires or other luxuries. Compared to a Yaris, or my little Honda, the Volt is far more car, and far quieter.
Interesting that the Continental TSIO-550 has a BSFC of 0.5. Most aviation engines are considerably more efficient than that. The Typical number for fuel injected engines is 0.42 in cruise configuration. In fact, the simple addition of electronic ignition with a proper advance curve, on aircraft engines, often brings the BSFC numbers down to 0.38 Lb/hp/hr. Another thought about Jet fuel vs. Avgas. Jet A is 6.5 Lb/gal. Avgas is 6.0 pounds per gallon. Certainly, the energy content of the Jet A is higher than gas. Remember that a full tank of Jet A weighs somewhat more. Reducing useful load. I'd rather see an aircraft specific, 120 degree V6 turbodiesel, with a "hot-V" configuration (the exhaust exits above, into the V) with a centrally located turbocharger. This results in 3 cranks throws, perfect primary balance, and the ability to go direct drive. Gear reduction drives are particularly troublesome and expensive in aviation.
R-P, thank you for the more detailed thoughts on the Motiv design. It's a good bit of information to chew on. Know that you and I disagree on a number of minor points, such as reciprocating compressor efficiency, turbocharger effectiveness sans intercooler and the required heat transfer of the Motiv combustion chamber (I certainly don't see 2 tiny cylinders doing the work of 4 or 6 larger ones as thermally feasible) Even so, I do see why you have confidence in the Motiv design. And, I agree that with proper design, it's likely to achieve good BSFC numbers. Quote: "Only the work done by the piston turning the crankshaft is harnessed as net work output." Note: We regularly design turbocharged engines with more intake pressure than exhaust pressure, resulting in recapture of some exhaust energy. SJC, there will always be a need for energy portability. Being tied to the grid and/or batteries won't work everywhere. Aviation is one example.
This has been one of the more interesting threads on this site. It's nice to see such interest in alternate designs. I often reside in the past, so please excuse my vantage point. While the energy required to drive a turbocharger is not free, it's exhaust energy, not crankshaft energy. There are some advantages there, especially when compared to crank driven piston compressors. It's been done before and has never been effective on conventional engines. With the possible exception of the Shindawa hybrid 4 engine that used the area under the piston to compress air (even then, it's not a great success). Nor do I see packaging problems of turbochargers as a serious issue. Example: a "hot V" 120 deg V6 with centrally located turbocharger or inline 6 with directly mounted turbo. Charge air cooling can be used, or not. In the discussion above, no mention has been given to increasing the expansion ratio of a conventional compression ignition engine via valve timing and geometric changes. I also have to wonder about heat transfer issues in the main combustion chamber. In the gas turbine engine world, we maintain reasonable temperatures with massive quantities of additional air. How is such a small cylinder going to cope with such high thermal loading?
Which favorable area/volume ratio do you mean? The comparatively tiny, main combustion cylinder with it's unfavorable area/volume ratio by virtue of it's diminutive size? Larger engines are generally more efficient, largely due to: a) lower piston ring swept area, b) advantageous area/volume ratio's that reduce combustion heat loss.
I don't see why much of this can't be achieved, in a single cylinder configuration, with careful valve timing to optimize the expansion ratio, a very high compression ratio and modern controls. Without the excessive piston ring swept area and resulting frictional losses.
Don't forget the obvious, gasoline is lighter than diesel. So, even though BSFC numbers (fuel consumption by weight) are similar to diesel, the gasoline engine will consume a higher volume of fuel for a given output.
Can I interest you in a SouthWind combustion heater for your "cold weather" Tesla?
We've been talking about doing this for as long as I've been in the Aviation Industry. Yet, nobody has seen fit to produce a viable production setup. One thing to be mindful of, the main engines often need 5 or more minutes of warm up prior to takeoff. At my home base (Palm Beach International Airport) , the taxi is often less than 5 minutes. So, cold engines are started during pushback. While a 4% fuel savings may be possible during some congested and short routes, others won't see any savings at all and will pay the penalty of additional weight and maintenance. In years past, there was quite a bit of talk about a hydraulic system driving the nose wheels. I think the conclusion back then is that it was not worth it. I wonder what's changed? Possibly the long delays today...
I always believed that there could be interesting "tie in's" to GPS technology. For example, if you are lifting off the throttle and there is a known stop sign ahead, the GPS, coupled with the stop/start system would assist the system in cutting the engine at the first sign of "lift throttle". Same goes for regular commute patterns, and, of course rates of acceleration. I'd love to see an optional or selectable preset "most efficient" reasonable "acceleration rate" based on location on the road. 35MPH zone, vs highway on ramp. Even if it's just a tactile, detectable throttle detent that can be easily ignored if necessary. Systems like this could work for electric cars as well as conventional.
The Ecoboost Mustang should be a whole lot of fun. A bit of a throwback to the 2.3L powered SVO Mustang, which was, in my opinion, an excellent fun car for it's day. If Ford keeps the weight down, the EB car will be the typical favorite. Fords EB engines are nearly universally loved by consumers. With a wonderful wide torque curve and plenty of power, coupled with fair economy "if" you can keep your foot off of the go pedal. Don't believe me? Go test drive a Ford Focus ST and tell me that car is not an absolute blast to drive. And, I expect the '15 Mustang to be even better, with it's RWD configuration, IRS and significantly improved suspension. Seems like Ford's answer to BMW, at 1/3 the cost.
I find it interesting that the American manufacturers were the first ones out with this technology. Honda and others are following. That's quite different than a lifetime of technological implementation from the Japanese. I'm old enough to remember when the only 4 valve, DOHC, 4 cylinder cars available were from Japanese manufacturers. And, wow, were they nicer than the pushrod and SOHC clunkers of the American manufacturers. As for "Plug in Hybrids" with range extenders. Today, they are not good enough. The battery packs are too small, limiting the performance, the range too limited and the cost and weight too high. In my mind, for a PHEV to sell, it must perform extremely well under battery power alone. The engine should be a very secondary consideration. My recent Ford Fusion Energi test drive around the 9 mile "loop" city/highway resulted in a bit of frustration. On a full charge, the car could not achieve current highway speeds without engaging the engine. I made it to 67MPH, in a 70 zone, traffic moving faster than that. I was in the right lane, holding people up badly. After 9 miles of sub practical driving, the battery was more than half depleted. Even a school bus out accelerated me in the city section of the loop.
Quite a few votes here for the "plug in hybrid". I've driven a few and came away disappointed. Disappointed with the range, EV power, integration of the engine, and braking-regen. Especially so with the Ford Fusion Energi. I've driven the Tesla Model S, with the 85KWH battery and performance package. To say that I came away impressed is the understatement of the year. I'm in love with that car! Rather than see Tesla (and others) make use of a "smaller and lighter" battery as some here suggest, why not use the same physical size battery with 250% more Specific Energy? Instead of 250 practical miles, possibly 600 practical miles! Now, all of a sudden, you have a car that is practical for our immense interstate system. Charge at hotels/motels overnight, and be on your way in the morning. And a "once a week" charge becomes practical.
I'd absolutely love an electric car. However, here in South Florida, traffic moves fast, about 80 on I95. This car, with it's 24KWH battery would not have the effective range I need for the daily commute 28 miles each way, plus a stop at a nearby location that adds 20 miles. Add lunch to that, and a bit of shopping and the range falls 50 miles short of being "just barely" practical. No thank you.
A number of us have used E-85 in newer vehicles not officially designated for E-85. Even with the very high ethanol content, (around 70%) actual around here, there are no operational issues. Certainly, there is a loss of MPG's but no loss in overall driveability. It seems that modern ECU's can adjust for the energy content of the fuel without difficulty. I believe using E-15 simply won't be an issue for any modern car.
Ummm, Davemart, It was a bit "tongue in cheek". But I guess you are to "dim" to get it.
I am not persuaded the mice based research is valid, for all the obvious reasons. They were immersed in a horrid environment and they got the expected results. Next, we can try swimming in gasoline... Heart disease has been with humans for all of recorded history. Careful study of well preserved ancient bodies clearly show heart disease to have been common. Early death due to atherosclerosis has a large genetic component. I wonder if ancient man died early due to sitting around the campfire? Or if the type of wood used in said campfire affected lifespan?