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that's not true and I have proof
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Feb 17, 2019 06:28
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HAIL eSATA-n posted:that's not true and I have proof elon and the sexy SEC agent roleplay, eh
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Feb 17, 2019 06:57
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it blows my mind that the B-52 will be in service for a hundred years
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Feb 17, 2019 07:57
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Combat Theory posted:The absolute state of electric cars is a loving joke. BIGFOOT EROTICA posted:"my girlfriend used an electric car in the absolute worst scenario for using an electric car" big scary monsters posted:temperatures of -5C and 200km trips are not really a weird or unusual thing to expect your car to be able to deal with in many parts of the world that would like to be able to use electric cars infernal machines posted:cue some AI reading dipshit going evil_bunnY fucked around with this message at 11:49 on Feb 18, 2019 |
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Feb 18, 2019 11:36
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ICE cars lose efficiency in the cold too you know! like it's in any way relevant
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evil_bunnY posted:LMAO I mean sure but why would she try it and why would you let her. Which is interesting because the makers these days are starting to move toward smaller, but turbocharged, engines. A small turbo will spool up practically instantly. Apropos of nothing, production diesel locomotives have been turbocharged in the States since 1962 with the introduction of the GP20. Given that every Class I railroad these days, except maybe Kansas City Southern, crosses mountains, and a majority did back in the day as well, turbocharged diesels swiftly took over. EMD did offer "naturally aspirated" engines (they were roots blown, but it's a 2-stroke diesel) for a long period after that, but they swiftly fell out of vogue post GP/SD38. So yeah, locomotive makers figured out that turbocharging was needed for passes long ago. iospace fucked around with this message at 14:51 on Feb 18, 2019 |
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Feb 18, 2019 14:49
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iospace posted:Which is interesting because the makers these days are starting to move toward smaller, but turbocharged, engines. A small turbo will spool up practically instantly. why was a turbocharged solution better than the supercharged 2-stroke
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Feb 18, 2019 21:23
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Notorious b.s.d. posted:why was a turbocharged solution better than the supercharged 2-stroke less poo poo hanging off the driveshaft wasting energy when not necessary
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Feb 18, 2019 21:34
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Cocoa Crispies posted:less poo poo hanging off the driveshaft wasting energy when not necessary how does this specifically help at altitude not being snarky, i am actually curious
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Feb 18, 2019 22:50
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Feb 18, 2019 23:26
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Notorious b.s.d. posted:why was a turbocharged solution better than the supercharged 2-stroke less infighting between clarence carter and billy squier
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Feb 18, 2019 23:45
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Notorious b.s.d. posted:how does this specifically help at altitude there’s less air at altitude and if you have some kind of air compressor between atmosphere and the manifold you can put more air in the cylinder a turbo is powered by exhaust and if there’s not much of that it just kinda windmills a supercharger is hooked right up to the crankshaft and is always compressing air if the engine is turning turbos are a lot simpler which is why they’re on any forced induction car that’s not the top end corvette or something
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Feb 18, 2019 23:48
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Chris Knight posted:less infighting between clarence carter and billy squier lol
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Feb 19, 2019 00:15
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Cocoa Crispies posted:
yeah this is wrong Turbochargers are hella complex and the reason we see them fielded so heavily nowadays is because a lot of the development work is outsourced to the Turbo OEMs. In the Era of WW2 piston flight, where the power benefits of a turbo charger could mean the difference between aerial victory or defeat, Aircraft engines were still sporting Centrifugal superchargers because thats about as good as engineerig got back then. The pairing tri force of Combustion Engine, Compressor and Turbine at the incredible exhaust gas temperatures of a Gas Powered Engine was too much for that defining time of Piston Engines and it remains a challenge all the way up to today. A Roots Blower is a comparatively simple machine and can be paired to an engine with one page of hand calculations and maybe a diagramm, if not just a stats card. A centrifugal supercharger is already a league more complex and a Turbo requires excessive studies of Fluid dynamics and Thermodynamics to merely comprehend enough to judge a proper selection. Let alone design one. The roots blower is antique. The Centrifugal supercharger is a remain of times when OEMs were afraid of the exhaust gas temps and too cheap to invest into heavy cooling and sensoring. Its celebrating a resurrection currently with some OEMs due to the ability of providing adequate low end boost with 48V electrically driven Superchargers before a bigger turbo spools. The advantages of turbo chargers are very simple and immense. you get the compression work for free. A Supercharger will consume up to 20% of your engine Power to do the same. The cost is its complexity and agony of forever being slaved to exhaust gas temperatures, which will ruin your high power efficiency especially with modern, downsized powertrains. Combat Theory fucked around with this message at 00:49 on Feb 19, 2019 |
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Feb 19, 2019 00:46
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my supercharged AMG benz had an electromagnetic clutch that could engage or disengage the superchargerquote:The Lysholm compressor, conceived by a true unsung hero of 20th century engineering, Alf Lysholm, 1893-1973 (he also pioneered in gas turbines and torque converters), uses two counter-rotating screws, male and female. Vaguely resembling worm gears, they seize the air and squeeze it into the case axially. The result: The Lysholm is some 15 percent more thermally efficient, and 5 percent to 10 percent more volumetrically efficient than a Roots blower. But until a few years ago, the Lysholm’s complex rotor profiles, with some 700 critical reference points, were too difficult and expensive to mass-produce. With the latest manufacturing techniques, not any more. Those in the E55 are precision aluminum castings, coated with Teflon. At a crank speed of 6100 rpm, the E55’s Lysholm rotates at approximately 23,000 rpm, and coupled to an air/water intercooler with its own coolant system, produces 11.6 psi of boost for a maximum output of 469 hp. The normally aspirated 5.5-liter AMG V8 produces 349 hp, in an otherwise similar state of tune. There is a 34 percent increase in max power, but that is only part of the story. Thanks in part to the blower, there is 516 lb-ft of torque on call (100 more than the 444-hp Audi RS6 turbo). And it is there from 2650 rpm all the way to 4000 rpm. If you run the numbers, that torque equates to 235 psi of mean effective pressure over that entire range. (And the need for that ribbed crankcase sinks in.) At no point from 1500 rpm to 6000 rpm does torque ever fall below 410 lb-ft, and by 4000 rpm there is already over 400 hp on tap. but yeah modern turbocharging has supplanted supercharging in all but a few niche cars (the GM LT4 and LT5 and the twin-charged Volvo engines are all I can think of atm)
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Feb 19, 2019 00:56
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turbochargers use the exhaust heat and pressure to compress the intake charge, which means that you get the compression for free, since it's otherwise just blowing out the back. (there are a few slight inefficiencies in the exhaust scavenging but it's not really significant). they obviously run super hot and at super high RPM and as such are delicate machines. superchargers use engine power directly to compress the charge, being basically just a mechanical compressor driven off the crankshaft. the supercharger on a P-51's merlin engine takes 250 horsepower to run just by itself, but boosts the engine by more than that much, so it's still a net benefit. but you're still burning 1350hp worth of fuel to get 1100hp out so it's less efficient than the turbo method. superchargers are used because they're simpler to install and they start working instantly whenever the engine is spinning. turbochargers are more efficient and develop more power the harder you push them, but they're harder to design and install because of the metallurgy and exhaust routing and whatnot, and until recent developments there would be a noticeable lag in power delivery as exhaust pressure built up and got the turbine spinning.
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Feb 19, 2019 01:20
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https://www.youtube.com/watch?v=Q8diCicc3yw the sound like firecrackers that you hear in this video is a turbo anti-lag system. this system deliberately misfires the engine when it's close to idle, dumping unburned fuel into the exhaust manifold, where it ignites and keeps the turbine spinning. this means that it's already at operating speed and producing full boost when the driver floors the pedal. the only side effects are that it sounds like a machine gun and fire comes out of your exhaust and if you do it too long also turbocharger parts will come out too.
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Feb 19, 2019 01:28
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Pretty much all of the above, and the EMD turbos were actually hybrids. They'd be engine driven at low RPM, since 2 stroke diesels do not pull in enough air themselves. Once the RPMs got to a certain point, the clutch would disengage and it would operate as a normal turbo.
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Feb 19, 2019 01:34
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Sagebrush posted:https://www.youtube.com/watch?v=Q8diCicc3yw drat they found a way to make rally sound cooler
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Feb 19, 2019 01:35
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Sagebrush posted:https://www.youtube.com/watch?v=Q8diCicc3yw do they ever use electric motors to spin up the fans for anti-lag? seems like it might be a little more reliable long term.
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Feb 19, 2019 01:42
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I doubt you'd use an electric motor when you have a perfectly good source of rotational energy already there. But sometimes you use a clutch mechanism to drive the compressor from the crankshaft when the exhaust pressure isn't high enough to do it on its own.
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Feb 19, 2019 01:55
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Shaggar posted:do they ever use electric motors to spin up the fans for anti-lag? seems like it might be a little more reliable long term. Formula one does that, yes. But F1 Powertrains are 100% custom made prototypes start to finish Rally does not, quite simply because there are no adequate available solutions for turbo running gear that incorporates an electric motor and putting said motor near to an 800+°C exhaust gas powered red hot snail house is a much bigger hassle reliability wise than anti lag.
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Feb 19, 2019 02:24
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nice tesla model 2.5
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Feb 19, 2019 02:34
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Agile Vector posted:nice tesla model 2.5 it's a model <
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Feb 19, 2019 02:36
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Shaggar posted:do they ever use electric motors to spin up the fans for anti-lag? seems like it might be a little more reliable long term. I believe the latest Acura NSX does something like this.
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Feb 19, 2019 03:33
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Agile Vector posted:nice tesla model 2.5 Tesla Model 451
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Feb 19, 2019 03:34
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Powershift posted:Tesla Model 451
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Feb 19, 2019 03:46
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Powershift posted:Tesla Model 451 hahaha gently caress
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Feb 19, 2019 03:49
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Powershift posted:Tesla Model 451 lol
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Feb 19, 2019 03:52
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ok so we got an entire page about the tradeoffs of turbocharging and supercharging, which i already understood to my satisfaction in automotive applications what, specifically, about high-altitude locomotive applications made the supercharger + 2-stroke less effective than supercharger + turbocharger + 2-stroke seems like compressing the air should work pretty drat well in either application, and you would just see higher efficiency from the "hybrid" approach with combined blower + turbocharger if it was just efficiency i guess that makes some sense. not that diesel was all that expensive back in the day
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Feb 19, 2019 03:54
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Two stroke diesels as a whole are a bit weird when it comes to forced induction since they need it to operate. They can't scavenge properly otherwise. A two stroke diesel with a Roots blower operating below a certain level is considered "naturally aspirated". Even the ones with traditional turbochargers usually have a blower as well because otherwise they'd need an external source of forced air to get started. The turbocharged Detroit Diesels are actually twincharged by normal four-stroke standards.
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Feb 19, 2019 04:07
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wolrah posted:Two stroke diesels as a whole are a bit weird when it comes to forced induction since they need it to operate. They can't scavenge properly otherwise. A two stroke diesel with a Roots blower operating below a certain level is considered "naturally aspirated". Even the ones with traditional turbochargers usually have a blower as well because otherwise they'd need an external source of forced air to get started. this is cool and i did not know this it makes intuitive sense
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Feb 19, 2019 04:22
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Notorious b.s.d. posted:ok so we got an entire page about the tradeoffs of turbocharging and supercharging, which i already understood to my satisfaction in automotive applications It's always the same story. It's less effective to compress air by using engine Power than using waste enegery in the exhaust stream to drive the compressor. The more you go towards stationary operation, low exhaust Temps (diesel) and continuous high power operation, the more the advantages of a turbo charger are apparent. Don't just think in efficiency in terms of fuel economy, also think power availability. Having 20 percent less power available because you need to drive a compressor means you can haul 20 percent less weight uphill at the same speed, you can (roughly) only reach 80 percent of the travel speed of the turbo engine. A transport weight loss of 20 percent can easily eat up your profit margin even if you completely leave aside the fuel economy. Specifically to the case of 2 stroke engines, they are not self flushing. A four stroke engine will fill and evacuate the cylinder by means of piston motion if left alone. A 2 stroke practically universally has a port controlled intake. The piston is just controlling the opening and closing of the intake port. Without a positive pressure differential between the intake and the cylinder, no charge would flow. In smaller 2 strokes, this pressure difference is provided by crank case compression below the cylinder (also the reason for the crank case Reed valves) Crank case compression is very cumbersome because your engine now burns lubricant, you can't use hydro dynamic bearings, your crank cases need to be vacuum isolated for every crank pin, you can't build V engines with a large bank angle, yadda yadda. Now if you wanna build a good bottom end without all of the disadvantages of crank case compression, you need other means to provide boost and you need to provide boost at every rotation, full load, partial load, idle and cranking. A turbo won't do that. Running a supercharger is the easy solution. Building a sequential setup where the supercharger is switched off when a large turbo is ready to provide boost is the optimum of both worlds.
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Feb 19, 2019 13:06
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Notorious b.s.d. posted:ok so we got an entire page about the tradeoffs of turbocharging and supercharging, which i already understood to my satisfaction in automotive applications people keep saying that superchargers for large engines take hundreds of horsepower to turn but the trouble with that isn't the energy requirements it is the fact that dealing with that mechanical drive power makes it a pain in the rear end to adjust the ratio of the speed of the supercharger to the speed of the engine. you basically need something along the lines of an automatic car transmission. check out the Merlin's setup to get two speeds out of its supercharger:  the slow speed would be used at takeoff and once at altitude the supercharger would be switched to the higher speed to better compress the thin air. a locomotive supercharger would need to do similar to handle high altitudes but would face additional complexity because unlike a fighter aircraft engine (which was basically run near or beyond maximum rated power at all times) a locomotive engine needs to be able to handle different loads. the speed of a turbocharger on the other hand has a bit of a natural compensation (less exhaust back pressure at high altitudes, but very minor really), automatically goes up under load due to higher exhaust temperature/mass/flow, and most importantly can be directly varied by making the turbine more or less efficient at extracting energy from the flow. that last bit is the really critical advantage and improvement area for turbochargers since about the 50s because it lets you finely adjust the ratio of turbine speed to exhaust flow without dealing with switching the path of hundreds of horsepower. simple designs just allowed excess exhaust to bypass the turbine entirely but that was gradually replaced by setups which adjusted the angle the gas flow hits the turbine blades. a similar thing has been used for hydroelectric turbines since the 1860s, although the calculations involved in setting such a configuration up for a compressible medium like air undergoing large temperature swings are orders of magnitude more complex and handling that flow requires materials which don't erode or melt in a hot exhaust stream. so basically turbochargers are easier to adjust on the fly than superchargers which makes them more useful for changing conditions. they however require a hell of a lot more design calculations and complex metallurgy which is why they only really started to be a thing at all in the 60 years or so.
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Feb 19, 2019 15:12
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Combat Theory posted:red hot snail house mods
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Feb 19, 2019 15:37
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What if we designed a cycle that intakes and compresses air, ignites a fuel, and uses a turbine in the exhaust like a turbocharger but, like, that's where all the power goes Elon I have a disruption idea for the Model 4
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Feb 19, 2019 18:04
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A jet but instead of petrol, you dump in vape batteries and point the apparatus at a firetruck
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Feb 19, 2019 18:05
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Potato salad reinvents the joule cycle and gas turbines E: f,b
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Feb 19, 2019 18:07
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Potato Salad posted:What if we designed a cycle that intakes and compresses air, ignites a fuel, and uses a turbine in the exhaust like a turbocharger but, like, that's where all the power goes but dude, imagine this, the same as what you said, but steam powered.
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Feb 19, 2019 18:14
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Potato Salad posted:What if we designed a cycle that intakes and compresses air, ignites a fuel, and uses a turbine in the exhaust like a turbocharger but, like, that's where all the power goes https://www.youtube.com/watch?v=b2A5ijU3Ivs
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Feb 19, 2019 18:15
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and if you go steam, you can even skip the ignition and exhaust part and just use shiny rocks as your heat source
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Feb 19, 2019 18:15
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