Comments by "David Elliott" (@davidelliott5843) on "Engineering Explained" channel.

  1. Big motorcycles use more fuel and cost more to build than small cars. But scooter size bikes even the larger engine types are more efficient than cars. The big snag is use safety of bikes
    1
  2. nickie banchou Old style two strokes are dirty. Today’s are clean, very fuel efficient and powerful. Check out the Rotax used in Skidoo snow sleds and Evinrude outboards. They do use slightly more oil than four strokes but it’s burnt cleanly with the fuel and there is no waste oil to be disposed
    1
  3. Isaac Karjala Today’s motorcycles have fuel injection, catalysts, variable valve timing and even keep one inlet valve shut for low power needs. Rotax ETEC 2 strokes are super clean, very fuel efficient, lightweight and powerful. the 800cc Skidoo beats (at all levels) competing 4 strokes with 1200cc
    1
  4. Epotheros But a commuter car carrying one person uses nearly double the fuel and four times the road space of a medium size motorcycle carrying one rider.
    1
  5. Mr Squeak The Cat. Big powerful cars are not fuel efficient. Funnily enough big powerful bikes are also not fuel efficient. But you don’t need 1200cc and 150bhp to get to the office. A 250cc scooter is more than adequate and will do 80mpg or better.
    1
  6. Tesla does not have many super dooper V3 charge stations. But they do work. Other providers struggle to provide chargers that work at all. They have no Level 3 type.
    1
  7. Can we have a discussion on the Ice core and tree ring data that allows us to track climate and CO2 levels. Climate shifts over approx 1000 year cycle. 50” years cooler 500 years warmer. The evidence is that CO2 follows the climate curve. There is no real evidence that carbon causes global warming. In fact, its infra-red absorption wavelength is about the same as nitrogen and oxygen.
    1
  8. Should do a review of Fiat Panda 4x4. It’s small boxy and even more capable that the Suzuki Jimny.
    1
  9. You said the rolling radius is virtually the same but the aftermarket certainly LOOKS smaller diameter than the OEM. What's the difference if you measure one full turn over a smooth surface?
    1
  10. Why are Aston not using the Freevalve system? It would save weight and make more power per cc. Much less mechanical complexity Win Win. Surely?
    1
  11. Down hill will be almost totally trailer brakes. The last thing you want is an (effectively) unbraked trailer trying to overtake. There won’t be any regen braking on the level there won’t be very much. But even if there was, the car batteries probably could not absorb the power fast enough.
    1
  12. The gasoline car emissions should include those for engine transmission fuel system etc etc. Also the car batteries will not be scrapped when no longer suitable in the car. Used car batteries will be put into power grid support. Power walls etc.
    1
  13. How does they compare on CO2 emissions? Electricity is made by burning fuel. Gas/petrol cars burn fuel. That fuel is mostly emitting CO2 so how does that compare?
    1
  14. Why does Mercedes not use motors in each wheel with the engine driving a generator? We are told it's efficiency yet we are also told that mechanical transmissions waste 15% of the input energy (85% goes into moving the car. Today's electric systems are extremely efficient so why not offer battery power or engine power? Ignore hybrids (worst of both worlds).
    1
  15. STEEL wheels and flush trims. Easy to repair if needed and low costs if it’s not.
    1
  16. Many engines retard spark timing at cold start to put more heat down the exhaust for faster catalyst heating.
    1
  17. A mere 270 years ago (~1750) the world saw 180ppm CO2. It has since doubled to 400ppm. However, photosynthesis stops below 150ppm. We were incredibly close to a massive mass epidemic. Let that sink in. Despite the enormous damage we do, human activity may well have saved the planet’s ecosystem.
    1
  18. Water injection generates steam as it internally cools the engine and reduces peak gas temperatures. The benefit is reduced particulates and Nox low enough t not need a post treatment with AdBlue. As others said the issue is needing a water tank at least as big as the fuel tank.
    1
  19. What about stainless steel discs and sintered pads as used on motorbikes? They work extremely well and pads last 3x longer than organic pads.
    1
  20. High temperature (600C) nukes as in molten salts can do this. 1% of all the world's energy is used to make ammonia for fertiliser. No problem for high temperature nukes and ammonia can fuel ICE vehicles. Hydrogenate it and you get esters that make great diesel fuel. Portland cement is considered to be really bad on CO2 but the heat from high temperature nukes solves the problem with zero CO2 energy. Molten salt nukes make the heat at less cost per Kwh than coal and plant construction times compete with natural gas fired plants. PWRs can make electricity that's it. They only get built as government vanity projects. PWRs are fundamentally hazardous with huge engineering costs and very long build times to make them safe.
    1
  21. What about the Liquid Air engine. It’s a rotary but the stator is triangular with three combustion chambers and rotor is oval. It has a longer blowdown period runs quiet and efficiently.
    1
  22. Konisegg Freevalve solves the IC engine cost, emissions and consumption issues. But VW and others ignore it because they can’t claim it’s their idea. The same things happened with Orbital direct injection - we can’t see it - not invented here.
    1
  23. We do need to consider our electricity infrastructure. If everyone in my street was to connect an electric car overnight the street power cables would not be able to take the demand. I also think the small capacity batteries in such as Nissan Leaf will not be the norm. Their range is just too restrictive for most people. That puts more demand on overnight charging.
    1
  24. Everyone else uses auto transmission to prevent the driver trashing the gearbox. This one needs someone who can actually drive.
    1
  25. Electric cars will not need super powerful brakes because a significant braking load is fed back into the battery. They can’t entirely do away with brakes but they will be happy with much smaller units.
    1
  26. The late 1960s Triumph PI with Lucas mechanical sequential injection system was actually very good. Sadly it's reputation was ruined by mechanics who did not understand how it worked.
    1
  27. So what if it falls off the jacks? It’s your jacked up car. So :p to the pedants.
    1
  28. Stainless steel can tarnish. It does not rust.
    1
  29. Anyone complaining about CyberTruck A pillar should try driving a Merc Sprinter van. A whole Merc van can hide behind that. It’s horrible.
    1
  30. The Fiat MultiAir uses a normal exhaust cam. The inlet is opened by hydraulics. The valve opening height, duration and even number of openings are fully controlled. They could do it with exhaust but presumably the benefits are less.
    1
  31. stilkus your bike is more likely to have 10 brake pistons 8 at front 2 at back. Master cylinders bony count ;)
    1
  32.  @volvo09  The Rotax 850 E-TEC 2 stroke makes 160 bhp yet more than beats the US EPA emissions regulations while the competition running 1200cc four stokes struggle to meet the rules. Why can't we have that super clean 2 stroke technology in cars? It's lightweight, powerful (even at low revs), clean and low maintenance.
    1
  33. In 2006, I travelled 150 miles through very slippery snow and frozen rain. At times it was a nose-to tail crawl and never got above 30mph due to traffic. I ran out of petrol because the car used at least double its normal consumption. I (stupidly) ignored the fuel gauge because the needle fell so fast I thought it was broken.
    1
  34. Jimmy M Trig no worries even with book tables. Calculus I always struggled. Largely because mathematician teachers could not understand how to teach it to newbies.
    1
  35. Baby Magnum Physics is only arithmetic
    1
  36. Honda have a long history of getting it wrong with cam bearings and cam chains. So it's about time they managed to get the chains to last for the life of the engine. Engine life on a Type R will of course be a lot lower than the Accord.
    1
  37.  @SavageJim01  Even if it's "just" valve damage the repair costs can be huge and it's highly likely the crank bearing shells will be creased by the impact leading to rapid failure after the top end is rebuilt.
    1
  38.  @spankeyfish  Final drive chains on bikes could be fully sealed in oil and they don't have to look like a Honda Cub or CG125. Norton rotaries did it with rubber tubes to carry the chain and final drives would just go on and on. Another option is to run the chain over idlers so it's tucked against the swing arm and hidden by a dumbbell shaped cover that looks like a shaft system.
    1
  39. My 2007 Fiat 1.4 has an electronic pedal and throttle body. There is no sign of rev hang in normal use. However if you shift at high revs and get straight back on the gas, the ECU ignores the rapid pedal movement causing revs to momentarily drop. It’s not throttle hang it’s electronic induced throttle lag.
    1
  40. 48 volt electrics (actually 42V) were announced by Ford in the 1990s. It went nowhere because equipment manufacturers were not interested. Tesla wanted to use Ethernet cabling and communication around the vehicle. Power Over Ethernet (POE), operates between 37V and 57V. 48V sits in the sweet spot and allows Ethernet to power lights, cameras, etc with no additional wiring. 48V makes the heavy motors easier so it’s a no-brainer to go there.
    1
  41.  @nimblemotorsports  2 strokes running fuel and air through the crank case wear rapidly because uneven (poor) combustion causes the piston and crank loads to fluctuate badly at part load. Run continuously at >75% load and they have a very long service life, but for anything other than power generation that's just not a useful option. Direct injection strokers like the new Rotax ETEC engines solve most of those problems. They breathe clean air and only feed fuel direect into the combustion chamber when power is wanted. They don't get the widely varying fuel air mixtures, air flow reversals, etc that make "normal" 2 strokes so dirty, wasteful and short-lived.
    1
  42. David Vizard discussing valves and gas flow says exhaust gas inertia causes the cylinder to go negative pressure just after the exhaust valve opens. The inlet opens momentarily later so the incoming charge is pulled in by the partial vacuum created by the exhaust flow. Konisegg have the Freevalve engine which operates its valves entirely electronically. No cam, no cam belt, around 20kg weight saving on a 1600cc engine. Each exhaust valve has its own outlet pipe with only one going to the turbo. The other goes straight to the catalyst. The individual valve openings control how much boost is made. No waste gate. The cold engine keeps the turbo valve closed and retards the spark ignition. That puts flames down the exhaust to quickly heat the catalyst. The precast is not needed. There is also no throttle valve it’s all done by the engine valves. Check out the freevalve video.
    1
  43. Super cars are all about bragging rights. That’s it. The fan assisted ground effect cars were banned by F1 for cornering too well. However Ross Brawn said the external wings had replaced that lost downforce within 2 years. Unfortunately the wings’ wake turbulence badly affects overtaking.
    1
  44. Wankel is a two stroke. Why not fit reed valves and variable exhaust geometry. They have been around since the 1980s and fully refined by Rotax in their direct injected engines.
    1
  45. Steer by wire looks incredibly complicated for really quite small benefits. Ditto electric power steering, which always feels dead. The Citroen DIRAVI hydraulic system solved all this in 1970. By law it had a solid shaft to the steering wheel but everything else was hydraulically powered. This could easily be used in electric cars with a pair of electric motor hydraulic pumps. I feel it’s a great lost opportunity along with the Citroen hydraulic suspension system. It got a name for unreliability but that was actually caused by mechanics refusing to understand the technology and of course rust which rotted into every car back then.
    1
  46. Koenigsegg say a Freevalve is cheaper to build than an equivalent standard cam engine. The TFG is only expensive because it's been taken to the max is every respect.
    1
  47. Lean mixtures don’t send enough HCs down to the cat. Catalysts overheat when the exhaust gas is too rich. Burning off the unburnt fuel overheats the cat. Cooling the exhaust gas allows the turbo to work harder at lower power settings without getting over cooked at full throttle.
    1
  48. Using the average gasoline emissions for the high power high vale electric cars is actually unfair because they are really competing against the gas guzzlers of the gasoline world. That makes an even better case for electric cars.
    1
  49. The last time I saw -18°C was 1981/82. My VW splitty van (12V system but 6 volt starter motor) slipped more than it went where I really wanted it to, but it always started no problem. At the same time, I was helping neighbours jump lead starting brand new cars. My biggest problem was ice INSIDE the windows due to the notorious heating system on the VW boxer. I fitted little defroster heater elements to the windscreens which worked better than expected.
    1
  50.  @decayofalberta1520  So much misinformation. Tesla Model 3s are holding their value amazingly well. The 130 miles per (US) gallon equivalent mileage makes them use less CO2 than any engine car after two years at average miles per annum. More importantly Tesla have proved the battery life is at least 300,000 miles and potentially 400,000 or more. Very few engine cars get beyond 150,000 miles.
    1