Comments by "Devil\x27s Offspring" (@devilsoffspring5519) on "Engineering Explained" channel.

Using a much higher voltage allows them to keep the current from getting out of hand at very high power levels. So, it reduces losses in the motor and controller. But, if the car is heavier and has higher rolling resistance, it will still use more energy. If the Porsche was designed for best possible grip, it probably isn't using tires that are intended for the lowest rolling resistance, and it's a really heavy car to boot. Combine those two things and you have higher energy consumption. Doesn't mean it's a design flaw, it's just the way it is.
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@CFG39 The Tesla Model 3 uses a permanent-magnet brushless DC motor, which can be 95% efficient or even slightly more. Other electric cars are generally using AC induction motors, which offer insane starting torque and extremely high power density, but are 'only' about 80% efficient--which is still very good. Incredibly expensive performance cars use the AC motor for it's ideal characteristics when accelerating an inertial load (car!) from a standstill, but the less-powerful DC motor is more efficient. That's why the Tesla Model 3 uses one.
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Very important correction! :) Thanks for clearing up. It seems obvious to me that the Civic 4-lunger certainly isn't running anywhere near that boost pressure either, certainly not on pump gas at 9.8:1 compression!
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@JRP3 That's right--but, the "hefty" model S is still using the AC motor, with lower efficiency, for the exceptional driving experience it offers: Phenomenal starting torque and fierce acceleration from a relatively light and compact motor. The DC motor is used on the front wheels for continuous power in constant-speed driving, and for higher efficiency in regenerative braking, combining the best of both worlds in a big, heavy, extremely expensive car :) A normal, everyday car would use only a DC brushless motor for best efficiency. It just so happens that the acceleration performance is very good, too--but nowhere near the outright 'muscle' you can get out of a similarly-sized AC induction motor. The tradeoff is the conversion efficiency.
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@scottbeaulieu13 Nothing wrong with wheels, even if anti-grav tech was available. Remember, wheels have traction, hovering does not. (I'm actually being serious.) But, this obsession with every damn car having to have huge rims and rubber-band tires is ridiculous--and this is why. Rough ride quality is another reason, though.
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@JRP3 I know that, it doesn't affect the pack itself, besides making the balance control circuit more complex. But, for a given power (in Watts) it reduces the current by half, which makes thermal losses less of a problem in the wiring, controller and motor.
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@name-jn3ri Ok, look at it this way: an engineer designing a consumer product like a car is primarily concerned with cost. With power semiconductors and the circuits they operate in, it's cheaper to double the voltage instead of doubling the current to double the power. It also makes the circuit itself, as well as the associated wiring, smaller and lighter. So, that's what Porsche did :)
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Pushrod engines don't intrinsically produce more low RPM torque than any other engine layout. It has nothing to do with pushrods. The major advantage is that pushrod engines have more compact cylinder heads. You can shoehorn more displacement into a given-size car using a pushrod engine. Overhead cam designs allow higher RPM for a given cam profile, allowing higher specific power (HP per litre/CI)
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@CL-gq3no Yes, there is! At twice the power it's much easier and cheaper to deal with twice the voltage instead of twice the current. Since you're an electrical engineering student you owe it to yourself to build some electric bikes instead of spending your student loan on beer, night clubs and fancy bongs. Build a simple DC brushed motor controller or two and you'll see that it's both cheaper and much easier to deal with double the voltage instead of current on an actual, real-world application!
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@jakecole7447 It really runs at well over 20 PSI boost on pump gas at 9.8 CR? Somehow I really doubt it. For 300HP on a 2.0 liter 4, more like less than 10 PSI. 20+ PSI shouldn't be necessary for 300 HP, nowhere near that much.
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I used to play with rotaries, they're neat little gadgets and quite ingenious, but you're still better off with a piston engine. The lower thermal efficiency is a direct result of the Wankel's greater combustion chamber surface area, and that's it. Nothing to do with plug location, port timing or location etc. Sealing was very good on RX-7 engines, but of course they had to use oil injection, and that in conjunction with high fuel consumption means that emissions compliance is that much harder to achieve. And frankly, a high specific fuel consumption and difficulty reaching emissions requirements will kill a powerplant for use in cars--simple as that. If you like funky power systems in your cars, have a fascination with rotating machinery for whatever reason, want to drive something really zippy, and have the dough to back it up--buy a Tesla :)
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I don't know if "sophisticated" is the right word. The main advantage these engines had was simplicity. They were designed to be easy and cheap to build in quantity. The only major advantage the Flathead engine has, other than simplicity/cheapness, is compactness--an engine of a given displacement is smaller than an overhead valve engine because of the flat, simple cylinder heads.
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If Honda can do that with a Civic out of the box, imagine what they could do if they put the same amount of power down through the RIGHT (aka rear) wheels ;)
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With sufficient traction, probably almost any vehicle will climb a 100% grade.
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In a nutshell, Stepping on the brakes: The car's speed and weight (kinetic energy) are lost as heating and wearing of the brakes. Shifting into a lower gear and closing the throttle (taking your foot off the 'gas'): the car's kinetic energy is lost by the air cooling down and losing pressure very quickly as the air is sucked past the nearly-closed throttle valve, allowing braking to occur without any mechanical wear and tear. For absolute best fuel efficiency (no wasteful braking, or kinetic energy dissipation, of any kind), climb a hill at a low speed in the lower gears, then shift into neutral at the top of the hill, and just let it coast downhill at whatever speed it wants to with no braking of either type! Watch out for cops at the bottom of the hill :)
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Wow, sequential twins AND and electrically powered supercharger?! Plus all the plumbing and wiring to get it all working together decently? Why not just use a bigger engine and be done with it?
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Can't beat the entertainment factor and lower cost of the manual. Can't beat the convenience of auto. Once the manual's entertainment factor wears thin for you after you've been driving for a couple decades, the manual loses much of its lustre--but it's still cheaper, and if you don't have to do a huge amount of stop 'n' go city driving, it's probably the better choice if you know how to drive it. Manuals still benefit/suffer from a certain elitist/snob-appeal aura, but as someone who's driven manuals almost exclusively, I can assure you it makes hardly any difference for day to day transportation. It's cheaper, and generally slightly more efficient, and if you don't mind learning how to do it, it might be worthwhile for you. All this "authentic driving experience" and "real drivers drive manual" is mostly blowing smoke.
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@JRP3 That's right, but using standard, commercially available power semiconductors available at low cost, a given circuit design can handle twice the power at twice the voltage without excessive heating becoming a problem. Overall, it probably doesn't make much difference. Porsche chose a higher-voltage system to allow high power levels without the current getting really out of hand. A similar power output could be reached with half the voltage, but you have to deal with insane currents, and the peak transistor current in the Tesla Model S is already probably well over a couple thousand amperes when starting from a standstill.
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@gormauslander Maybe "permanent magnet synchronous motor" would be a better description. They can't run directly off of a DC supply without the electronic commutation circuit, so calling them a DC motor is a bit of a stretch. But, they're generally referred to as BLDC motors even in industry.
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Really big engines have the best drivability--the engine is very versatile. The throttle response is instant and there's no "surprise" belt of power as a turbo starts to produce boost. However, large engines generally produce more emissions. So, to minimize emissions (and weight) while keeping power levels high, they use smaller turbo engines. That's all there is to it. Nothing more to it than that. Turbos are a great hobby-they're fun to play with, but for overall driveability, you're better off with a big NA engine.
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