General Car Discussion

Discussion in 'Automotive' started by HadACoolName, Mar 6, 2015.

  1. Slugfest

    Slugfest
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    Ooh, crown vic - I hope you get that transmission working, they're great cars :)
     
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  2. redrobin

    redrobin
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    This is why I'm scared to rebuild the transmission in my Jeep. All the magic that's in there making it still semi-functional will disappear.

    It's like a junkyard LS motor. Pull it directly from a truck then turbo it. DO NOT OPEN IT!!!!! It let's the magic out!
     
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  3. ARES IV

    ARES IV
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    I have always been fascinated by technology and dived deep into the physics and mechanics of ICEs. Yet, the more I knew about them, the more I began to understand their limitations and how many of those make them in fact rather poorly suited for the operating conditions that is average car driving:

    • Cold start: when an ICE is started cold, it endures increased wear and tear as it takes a moment for the oil in the sump to travel to all moving parts. The colder and more viscous the oil, the longer it takes in addition to having reduced lubrication properties compared to warm oil. In extreme conditions, the bypass valve in the oil filter may be triggered, allowing unfiltered oil to reach the engine.

      Pistons become pretty hot under sustained operation and slightly increase in size as a result. To avoid piston seizure, it is necessary for cold pistons to be slightly to small for the cylinder. This increases blow by of combustion gases, leading to reduced lubrication properties and oil poisoning, a fact further amplified by fuel condensating on the cold cylinder walls. Some mostly short distance driven Diesels can in fact be prone to an ever increasing oil level as more and more diesel makes it way into the motor oil. Which is bad, because it has far less lubrication properties as motor oil. Petrol has even worse lubrication properties but at least boils off when the engine oil gets hot, unlike diesel fuel.

      An cold ICE has horrible efficiency and emission values for the first minutes of its operation. While the worst part of it is over relative quickly as the engine warms up, it may need up to 20 km (or even 30 km for large diesels) of normal driving to truly reach operating temperature and as such its full efficiency potential. This is a major factor in fuel consumption when you dont drive long distances as the enormous waste of the first few KM is divided by relative low total travel KM. It also helps explaining why efficient ICE vehicles spend a lot of effort on
      - maintaining heat (thermosbottle for toyota hybrid, higher thermal capacity engine block for fords ecoboost in addition of water cooled turbocharger)
      - reduce the size and mass of the engine block as a smaller engine heats up faster for a given power output.

      Catalytic converters require arround 400°C operating temperature. To achieve this temperature asap, they are usually mounted close to the engine and your ECU has just one single goal after cold start... heat it up. Ignition timing is altered to achieve this, further increasing fuel consumption as more of it burns in the exhaust. The close mounting towards the engine has also a major drawback.... under sustained engine load (think highway driving) the converter could overheat and melt... to avoid this there are two possible solutions:

      1. Mount the converter further away from the engine and heat it electrically so that it still manages to get hot enough in time.

      2. Enrich the fuel mixture to cool the exhaust gases down a level where they wont melt the converter.

      Take an educated guess which solutions is choosen for price sensitive mass marketed cars...

      This is the reasons why some cars begin to guzzle fuel like mad past a certain speed. You are literally cooling the converter with fuel. It also helps explaining why water cooled turbochargers can be significantly more efficient, they do not require this as much/at all. Bonus points for being a diesel, which has much lower exhaust temperatures in the first place.

    • Fuel economy and clean emissions can be conflicting goals: Catalytic converters are great for air quality and the environment (if you drive more than 5km that is) but they cost fuel. Both for heating up first and more importantly that require an stoichiometrically fuel air mixture at all times. This leads to greatly increased fuel consumption compared to lean burn engines (for example diesel) at lower load conditions. For example my 1.6L petrol engines requires the same amount (0.7L /h) of fuel at idle than an 2.0L turbodiesel because it is not allowed to lean burn.

      Fun fact: Diesels at maximum load arent that much more efficient than petrol engines, they gain most of their real life advantages in partial load situations - which are the majority of driving.

    • Real life driving is 99 % partial load driving which further reduces the already not impressive efficiency of ICEs as they are ill suited for partial load conditions. Petrol engines suffer from throttling losses and mechanical losses are identical for a given RPM independent on load. (3000 RPM at full load has the same mechanical losses at 3000 RPM at almost no load)

      The idea of downsizing engines is based on the simple truth that fuel consumption is primarly decided by partial load efficiency and not by full load efficiency. It doesnt matter if your small turbocharged engine consumes more when getting up to speed when it will consume less for the next 100 km compared to a bigger non turbo one.

    • Rotation speed and reciprocating motion issues:

      The useful power band of the average naturally aspirated petrol engine is only arround 5000 RPM: (1000 idle, 6000 RPM peak power)
      1000 - 2500 RPM - good fuel economy but poor power output
      2500 - 4000 RPM - average fuel economy and power
      4000 - 6000 RPM - poor fuel economy, good power

      A diesel engine has even less than that.

      The inability to of the engine to smoothly rev below idle makes a clutch like device mandatory. It also makes multiple shiftable gear ratios mandatory to meet both power and fuel efficiency demands in most driving situations. This introduces additional drivetrain losses and mechanical complexity compared to a single gear reversable electric motor.

      Fun fact: Many ICE transmissions historically have not been optimized for fuel economy but top speed and acceleration, leading to unnecessary high RPM at legal highway speeds. A fact not helped by most fuel economy/emission testing being done at mostly lower speeds.

      The reciprocating motion causes vibrations and limits the upper RPM range of most production engines to arround 6500 RPM. Mean piston speed proves to be a pretty hard limit, mandating shorter strokes for higher RPM engines which hurts low speed torque and thus power.

    • The need to pump a lot of air through the operating engine makes air and exhaust routing an imperative design consideration. Valve timing - if not variable - is always a compromise between low end power and high end power. You cant have both. A Valve timing optimized for low end torque and efficiency is poorly suited for high RPM high power outputs and vice versa.
    • Exhaust cleaning on a mobile, not always running platform will never be as good as a the one in a large stationarly building. Even the much scolded coal power plants are cleaner per power produced as any ICE car engine can ever hope to be. Not only does it not have size and weight contstraints of exhaust cleaning, it also does not tend to shup down and start up 2 times a day with all the cold running emissions and efficieny issues.

      So yes, even if your EV runs on dirty coal... you on average are still better for the environment than burning petrol or diesel directly. For every Watt generated from cleaner sources, it gets even more superior.

    • Torque Curve:
      Why did turbo diesels became so popular? Almost certainly not for their sound. But as it turns out, most car buyers are willing to make sacrifices in this regard if the propulsion in question is both fun to drive and cheaper to run.

      The majority of car buyers was willing to suffer diesel knocking in exchange for better low RPM driving and cheaper running costs. It seems a pretty safe bet that they will get over the lack of "Vroooom" in exchange for quiet smooth power. Due to the basic torque curve of electric motors usually used in EVs, they feel much more powerful than ICEs of comparable rated power unless you rev those up very high. Which people tend to avoid because both noise and fuel economy tend makes them reconsider.

      You can be as fast in your 100 HP petrol car as an 100 HP diesel car... but you require much higher average RPM which makes them feel far less confident in comparsion. Electric motors rev up much higher (ID 3 = 16000 RPM) but since they are little more than a shaft spinning inside a magnetic field, they do so without creating remotly as much noise and vibrations as reciprocating piston engines. They also last much longer due to much lower thermal and material stress while also requiring far less maintainance.

    An electric motor has no cold start, it has no need of thousand of Euros worth in auxilarly equipment that an ICE needs to meet today power and emission standards. It runs from -50°C to +50 °C without any significant effect on efficiency or wear. It has almost zero local pollution. It allows for remote cooling and heating without an ICE running and polluting the neighbourhood.

    It is plain superior. Look arround you... how many things outside of your car are powered by an ICE? Not many.... because electric motors are superior.


    I dont hate ICEs. I would not research something that I hate so comprehensively. :)

    It is just... that being so fully aware of its issues and limitations... that I realize that for cars, it is doomed. You cant bargain with physics... and physics say it cannot win. ICEs require more and more effort to be competitive... batteries are getting better and cheaper..... some studies expect production cost parity by 2025.... this has one end and one end only.

    This is going to be the last decade where more ICEs than EV are going to be on the road. Hate it, dont care about it, love it... it doesnt matter. It will happen.


    You are sadly often correct. :(

    Yet on this particular topic, at least in my opinion, the - bribed - support for cars running on oil is going to doom the car manufacturers in question by the end of the decade.


    Electric cars always failed for 2 main reasons:
    • Battery cost and capacity = range
    • Charging speed

    While range is still a weak point in comparsion to ICE powered vehicles, things have greatly improved and we have finally reached values that are sellable in the mainstream. They also improve by arround 5 % per year on average so it is only a question of time until they will be good enough.

    The reason we are drowning in

    -E-fuels
    - Hydrogen

    advertisement today is simple the fact that the right people in big oil and gas (not to mention in ICE based companies) are capable of drawing that 5 % increase line for themselves into the future. And they dont like what they see and who could blame them... they are looking into the abyss, into the face of certain death.

    Of course they are fighting it with anything they can muster.


    Charging speed is approaching mainstream sellable values, too. Keep in mind that most EVs are charged at home so you may actually end up wasting less life time for re"fuelling" overall.

    Think about it: You plug in your EV at home when you park there in most cases. Unless you are making a long range trip, you will never ever see a recharging station from the inside. So yes, on long range trips you will loose 20 minutes compared to petrol or diesel, but the rest of the year you will never drive to any refuelling station ever again.



    Sorry for the wall of text. :p
     
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  4. default0.0player

    default0.0player
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    "When you abandon freedom to achieve security, you lose both."
    --- Post updated ---
    Interestingly, electric motor also has timing, commutation timing. An electric motor is an inductive load, the motor current lags behind voltage, thus the commutator(or the inverter in AC motor) has to switch polarity ahead of time to make sure the motor current pushes the rotor forward, i.e positive torque. The higher the RPM, the higher the impedance at a given inductance, thus the same applies to electric motor, it's not possible to design a motor that performs good in both high and low RPM.
    Unfortunately, there are many more. Here's a few example
    1. Overrated power/torque
    BYD Han is an electric car that "rated" 363kW power. However, the electric motors are overloaded, BYD only put the instantaneous power output on their car, which is 163kW/200kW(front/rear), the actual rated power(maximum continuous) is only 60kW/60kW(front/rear).
    In terms of Tesla Model S, even the instantaneous power output is overrated by about 20%. This is because Tesla rated their motors on a bench power supply, not on battery, the laptop battery pack simply cannot deliver that amount of power.

    2. Inconsistent power/torque
    When the battery is low, the motor power drops, this is because the battery is overloaded and the motor is underloaded.
    For example, if a battery pack has 420V when fully charged and 300V when fully discharged. Use the battery pack to power a 370V motor will cause this problem. This problem can easily solved by using a 300V motor instead and program the motor controller to limit voltage to the motor to 300V, then the motor can deliver 100% power even at 1% battery. The reason that car manufacture use a 370V motor is to make the power rating look better, and lowering cost.

    3. Questionable safety/crashworthiness
    The car may catch fire because of battery deformation(crashed), thermal runaway(overheated) or even software error.
    The problem is that most of the vehicle prioritize range by using LiNiCoAlO2 battery, which has a low thermal runaway temperature. LiFePO4 battery is safer but bulkier, which lowers the range.
    In comparison, fuel tanks wont catch fire even when shot upon via an anti-materiel rifle (source: MythBusters).

    4. Questionable range
    When showing their range, manufacture always use 100%~0% battery charge range. However when showing battery charge speed they use 0%~60% or 0%~80% charge time instead of 0%~100%. This is really misleading.
    Also electric cars often prioritize 0~60 acceleration in order to beat their ICE counterparts without using a more powerful motor, by using a high reduction gear ratio. This makes highway cruising less efficient and since in fuel economy tests the vehicle is at lower speeds most of the time, actual highway/freeway cruising range is significantly shorter.

    5. Worse handling
    Electric vehicle has worse handling than it's ICE counterpart. This is because of heavy battery. EV lovers often claim that EV handles better because of lower center of gravity, but there's reasons why no one ever lower there CoG by adding counterweight, unless there's a minimal legal weight.
    The eSBR 800 has much more horsepower than the SBR4 AWD TTS2, and EVs in BeamNG don't have Overrated power/torque or Inconsistent power/torque. But the lap times are about the same in those two vehicles.

    Take the Bluebuck as an example, land yacht, big block V8 good rated horsepower. Coolant overheating brake overheating after few laps on a racetrack, catches fire when rear-ended. Which is similar to many modern EVs' problems.
    In comparison, modern ICEVs are much better in terms of performance, the coolant rarely overheats. Even the base model Sunburst or 800-Series can be driven on a race track for 30 minutes without losing power.
    Fortunately, these problem of EV may be solved in a few decades, just like how the Sunburst has less problem than the Bluebuck. But for now, the problem above can't be ignored.

    The charging speed is because of
    When refueling, no chemical reaction is in progress. The refuel energy is a magnitude of megawatts(MW), but the power of the fuel pump is less than 100W.
    When charging, chemical reaction is in real-time, the battery must be able to react quick enough to absorb the charge. And for the charging station, charging at 100kW requires no less than 100kW power rating.

    Note: I'm not an ICE simp or climate denier. You already explained the advantages of EV, so I won't repeat them in this reply.
     
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  5. Potato

    Potato
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    Yes automatic transmissions are basically rube Goldberg machines that can be rendered completely useless if even one of hundreds of tiny parts is left out or misplaced.
    My original plan was to get a junkyard transmission but there is a currently a shortage of those in my area.
     
  6. SeaDooSnipe

    SeaDooSnipe
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    I just occasionally check in here, never really active but then again that's because I've lost interest in gaming, lol.
    Just picked up another bike last night, just a mid 90s RM125 that I'll be rebuilding and running some supermoto races with.

    Rev hang at idle might even be a vacuum leak or needs the next size up pilot jet. Those are fun little bikes.
     
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  7. Slugfest

    Slugfest
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    You do know alot about engines and their limitations, and all of the inefficiencies you mentioned are very real problems. Having said that, electric has many of their own problems, pretty well laid out by @default0.0player , and I would like to add one final thing: energy storage/consumption process.

    While this is not an EV specific problem, but rather a problem with electricity as a store of energy, it is major. Electricity through a motor may be a more efficient process, but the way the power is stored and consumed is poor for EVs. If I put Stabil in my tank of gas, I can come back two years later, and that gas still will provide the same amount of power. Additionally, as I use this two year old gas, it provides the same power until the very last drops. Electric batteries, on the other hand, lose charge over time no matter what, and after two years, what charge is left will not provide the same power as a full charge either, because of their nature. This is a big issue for batteries, and is not solvable as far as I know.

    Additionally, I gather that you do indeed like engines that make proper noises, and I urge you not to lose hope. Particularly in the U.S. I don't think people will be forced to go electric very easily, as the car has been built into American culture for so long that it being transformed into something so very different would not sit well.
     
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  8. NGAP NSO Shotgun Chuck

    NGAP NSO Shotgun Chuck
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    Hopefully I don't get banned for the old post you quoted, but dang do you ever know your stuff.
     
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  9. XManic1995

    XManic1995
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    Hell yes! Lada Niva is back in the UK
    Finallada.png
    (LHD only)

     
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  10. Potato

    Potato
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    Catastrophic failure in the shop today.
     
  11. P_enta

    P_enta
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    oh my god it’s everywhere
     
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  12. NGAP NSO Shotgun Chuck

    NGAP NSO Shotgun Chuck
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    When you finish breaking in your new engine

     
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  13. Potato

    Potato
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  14. Slugfest

    Slugfest
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    I think you need a few more lights on in the dash ;) It's nice that it's safe to drive though, given the last video :)
     
  15. Potato

    Potato
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    Yes the ABS and Brake lights are on because of an ABS controller internal fault. Red door ajar light is on because the passenger door wasn't latched.
    It is a good car, simple fix on the ABS and it will be no problem.
     
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  16. combatwombat96

    combatwombat96
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    my mechanic for no apparent reason changed the fuel pump when all i had wanted done was the bearings and a float readjustment. Now this wouldn't be a problem (except for the extra $180) if he had just bothered to check what pressure the pump was running at. From the factory it was about 4 psi, however all the websites state that all red 253's have an 8 psi pump (I even went to a Chev Power store to confirm that it is indeed from factory 4 psi). Now i have manifold filled with petrol. Great
     
  17. Slugfest

    Slugfest
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    ohhh, I'm sorry...
     
  18. combatwombat96

    combatwombat96
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    Wanna know his reasoning for replacing the pump
     
  19. Slugfest

    Slugfest
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    Sure, I love a good headache! :)

    Let me guess... he replaced it because it was only making 4psi?
     
  20. combatwombat96

    combatwombat96
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    "Because it was covered in gunk"
     
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