How to make a car more fuel efficient?

Discussion in 'Architecture & Engineering' started by weed_eater_guy, Jul 19, 2009.

  1. Dredd Dredd Registered Senior Member

    Messages:
    238
    What you are talking about is improving the way we use energy, because the fuel we use in cars now, petroleum, is not a renewable resource.

    So we improve the efficiency of the car. Ok.

    But if we replace the fuel with a renewable fuel that will work in the vehicle pretty much as is, without having to make it more efficient, that would be acceptable too would it not?
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Echo3Romeo One man wolfpack Registered Senior Member

    Messages:
    1,196
    Yeah, all of this is right on the money. The modern ICE under the hood of most vehicles is already extremely efficient, from the standpoint of BSFC. It's the ever-increasing amount of weight that's been added to vehicles over the years as a result of stringent safety standards that is keeping fuel economy from benefiting from the newer engine technologies. How much do you think side impact doorbeams add? How about 163 different airbags? Gadgets like navigation systems, DVD players, and premium sound also add to curb weight when you start piling them on. It takes a lot of energy to keep accelerating all that additional mass and bringing it back to a stop again and again.

    Smells like snake oil. Increasing the temp of gasoline lowers its octane, which is a big no-no with high compression engines. Also, that bit about exhaust heat turning gasoline into a plasma and being able to burn pickle juice is frankly nonsense. The only place fuel should be burning is, ideally, inside the cylinder.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. RickyH Valued Senior Member

    Messages:
    1,317
    you are correct. i will delete that post, because it may influence some one into the scam. with 2 minutes of research i noticed it had tons of press of it being a scam. i neglected to look into it further, when i posted about it.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. weed_eater_guy It ain't broke, don't fix it! Registered Senior Member

    Messages:
    1,516
    Go back to your trees, hippie! Just kiddin, I do totally agree with you, if that were made to work, that would be awesome, as would a couple other alternative energy solutions.

    I'm pretty partial to plug-in hybrid concepts myself where the generator is standalone and not part of the drivetrain, such as in the Chevy Volt concept. The idea is that you drive the first 40 miles or so on battery alone (charged from the wall overnight), long enough for your everyday commute, and if you drive longer then that for a road trip or something, the gas generator kicks in and keeps the power flowing with all the convenience of long drive ranges and couple-minute fill-ups.

    This powertrain concept has promise to be modular, where a car model could be made that the generator could be your choice of, say, a gas generator, diesel generator, CNG or propane generator, a hydrogen fuel cell, an additional battery pack (make an exclusive town car), or even additional luggage space (town car with a giant trunk?). Fuel tank space would factor in of course, either a plastic tank, metal tank, compressed air tank, whatever. A car built on this concept might just be a "gateway drug" to alternative energy vehicles, where you could buy the car now with a gas or diesel generator, then swap it out with a hydrogen fuel cell later.
     
  8. Emil Valued Senior Member

    Messages:
    2,789
    With Rotary Piston, but until now no one wants to understand.
     
  9. spidergoat Valued Senior Member

    Messages:
    51,799
    I like the safety stuff, but who needs sound insulation? Or a back seat?
     
  10. Westy Registered Member

    Messages:
    4
    1. Electric Power Train that can collect heat losses from braking and store it to be later used to power the engine during acceleration. A majority of the energy losses from cars is actually lost in the form of heat losses.

    2. Lighter Smaller cars, that have maximum speeds below 80 mph, as you can use smaller engines that are more efficient.

    3. Reduce the speed limits on high ways.

    4. Teach people to drive in traffic, I hate people that leave big gaps before they pull up. This type of behavior causes more traffic and thus increases the energy used to get from point A to B, and reduces the efficiency of the car. Also I think making using cellphones, etc, while driving would actually cause less traffic and accidents in traffic.
     
  11. Kernl Sandrs Registered Senior Member

    Messages:
    645
  12. Blindman Valued Senior Member

    Messages:
    1,425
    Easy way to improve efficiency is to put a block of wood under the accelerator. You can still get to 110kmh (max where I live). It will just take longer.

    An accelerating car can use up to 6 time as much fuel as just driving. Limiting the power by reducing max power output will save you a lot of fuel

    Via the block method you can reduce consumption to as much as a third...

    Cars should be fitted with acceleration limiters, it can save up 60% of your fuel consumption.

    But we consumers want power, and we only feel the power when we accelerate..

    Even on open roads the block of wood can save fuel as people tend to try to stay at speed, so when traveling up hill they will rather accelerate against gravity rather then slow and change down gear.

    Its so simple and would be the greatest saver of energy. A block of wood.
     
  13. Blindman Valued Senior Member

    Messages:
    1,425
    Ohh another one is get older. Older people tend to be less aggressive thus use less fuel.. Also women use less fuel so get a sex change if your a male...
     
  14. Kernl Sandrs Registered Senior Member

    Messages:
    645

    Where did you read that? I would like some statistics and data, please.
     
  15. spidergoat Valued Senior Member

    Messages:
    51,799
    Don't put a block of wood under your pedals, that's dangerous. It could get caught under the brake. Just don't accelerate so quickly.
     
  16. Blindman Valued Senior Member

    Messages:
    1,425
    Point taken. The best would be to fit cars with acceleration limiters. Modern car are fly by wire. It should be simple to do. Have a dial where the driver can set the max acceleration with an over-ride button near the gear stick. This would allow economy conscious people to easily control fuel usage as just controlling your pedal pressure takes a lot of self control and concentration.

    My new Falcon will use 8-10L per 100km on a level road at around 80-90kmph but with my foot down from the lights, it will go up to 40-50L per 100km. In city driving this adds up to a lot of fuel. It would be nice to set my car to a max of 15 or 20L per 100km.

    I know these numbers because the cars computer shows real time fuel consumption on the dash board.
    Saw it on TV so it must be true. :shrug:
     
  17. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    It is a little off thread, but there is an amazing fuel saving possible by lower the top of a long hill. (One so long that when going back down, you will need to use break).

    US 29 at the APL road exit was lowered about 25 feet to allow it to no longer be an "at grade" crossing. That took a month or two of bulldozer work. I crudely calculated how long it would take for the bulldozer fuel to be recovered (by no longer needing to break while going down from the top) - I forget but it was less than three months.

    Flatter roads so you never need to brake going down a hill can make cars more efficient going from A to B. Those deep road cuts you see at top of mountain are saving fuel big time.
     
    Last edited by a moderator: Jul 3, 2010
  18. greenfroguser5 Registered Member

    Messages:
    5
    i dont think it will be a great idea. because if you reduce air then the combustion will not be fulfill and the total utilization of the fuel will not be possible. so i dont think it will be cost effective. if you use pure air instead of natural air it will be great. but it is quite impossible!
     
  19. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    Adding very fine water drops to the fuel will definitely improve fuel efficiency. Some years ago I posted why I know this - experimentally. Here is what happens, I am almost sure:

    As the fuel burns, the water droplets convert into steam. This make the pressure on the top of the piston remain higher than it would normally be as the piston descends. Thus, the same fuel does more work. The energy for this extra work comes from the fact that the exhaust is cooler when the exhaust port valve opens.

    There is more heat released in the standard IC engine than you can use. This also slightly reduces the block cooling problem and extends (I think) the life of the exhaust valves. It also boost the power capacity of a fixed displacement stroke. - Some WWII piston planes did use water injection when they needed extra power. Carrying a lot of water would reduce their range, so it was only in emergency situations it was used. There may have been some "over-stressing" of the crank and bearings etc - I don't know, but suspect weight considerations limited the safety margins they had.
     
    Last edited by a moderator: Jul 3, 2010
  20. weed_eater_guy It ain't broke, don't fix it! Registered Senior Member

    Messages:
    1,516
    Billy, I never actually thought about it but wow, that's brilliant! But, I'm slightly skeptical for the sole reason that, well, if one wants to give a sports car a temporary boost of power, they carry nitrous, right?

    I am of course completely talking out of my a** and know next to nothing about high-end car tuning, it's just that I've never heard of anyone setting up their Type-R whatever-mobiles with a water-injection system, ya know?

    If water works, I wonder if peroxide would do something too, you'd have the extra expansion from steam generation AND a kick of extra oxygen! Probably corrosive as all hell though...
     
  21. spidergoat Valued Senior Member

    Messages:
    51,799
    It is used in high performance turbo-driven engines. It's application is limited, and it would not improve the gas mileage of a normal car.
     
  22. kmguru Staff Member

    Messages:
    11,757
    The water injection works as BillyT suggested within a range. One still wastes a lot of heat in the IC process. Collect and use that, you can increase efficiency. Best solution is to convert fuel to heat and heat to electricity to get 90% efficiency. But no one has developed a good large size thermo-electric process except people are still working on fuel-cell to electricity based systems for a while.
     
  23. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    Highly unlikely (I think impossible anywhere on Planet Earth.)

    "... If a solid state thermal to electric generator is Thermoelectric generators (also called thermogenerators) are devices which convert heat (temperature differences) directly into electrical energy, using a phenomenon called the "Seebeck effect" (or "thermoelectric effect"). Their typical efficiencies are around 5-10%will be very lucky to convert 10% of the thermal energy into electrical energy. ...

    Cars produce waste heat, and harvesting it can increase the fuel efficiency of the car. See the article Automotive Thermoelectric Generators* for the attempt to take advantage of this. ..."

    From: http://en.wikipedia.org/wiki/Thermoelectric_generator
    * http://en.wikipedia.org/wiki/Automotive_Thermoelectric_Generators , which discusses efficiency factors but does not give number; however, this quote from that link will give you an idea how low it is: "... Nissan's ATEG produced 35.6 W in testing conditions similar to running conditions of a 3.0 L gasoline engine in hill-climb mode at 60.0 km/h. ..." Note 35.6 W = 0.0477HP. I don't know much about cars but at 1% conversion efficiency that car would be making only 47.7 horse power. (I think it was much more if climbing steep hill and 60mph.) I.e. working in typical car exhaust I doubt even 0.1% of the thermal energy can be converted in summer.
    Your 90% is an impossible pipe dream.

    Fundamentally this is because there is always a reasonably conductive (both thermal and electrical) path between the hot and cold source and sink. I forget a lot of my solid state physics, but the "Fermi level" is elevated by heat and different in different material of a junction. Then the charge carriers (usually electrons, not "holes") "slide down" the thermal ramp of the changing Fermi level into the the cold junction material, but so does at least 90% of the heat energy supplied.

    All attempts to convert heat into higher quality energy, such as electricity of shaft horsepower are limited by the Carnot efficiency, Ec = (Th -Tc)/Th. where Th is the absolute temperature of the available heat source and Tc that of the sink to which some heat MUST be rejected. In any practical device that transfers heat (either income or leaving) thru a heat exchanger there is considerable reduction of the difference (Th-Tc).

    One of the attractive features of the IC engine is that neither the heat input nor waste heat discarded has to pass thur a heat exchanger. This advantage is not lost with water mist injection, but Tc is reduced if water mist is injected with the fuel of the IC engine.

    SUMMARY: It is theoretically IMPOSSIBLE to convert 90% of thermal energy into electrical energy anywhere on Earth (Only with huge radiators in deep cold space would Tc be low enough for that). In the Antarctic winter you might be able get about 60% conversion. (I am just guessing that Tc may be low enough there for that.)

    I don't want to be immodest, but I am quite sure that in terms of efficiency gain / dollar invested, nothing can come close to my suggestion of water mist injection.
     
    Last edited by a moderator: Jul 18, 2010

Share This Page