Hypermiling

Discussion in 'General Science & Technology' started by spidergoat, Jun 10, 2008.

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  1. spidergoat

    spidergoat pubic diorama Valued Senior Member

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    I pumped my tires to the max on the sidewall, 44psi (usually 31). I have a K&N oil based air filter, just cleaned and re-oiled, and I only use the AC when coasting. I also have an aftermarket exhaust system, larger diameter, and a cold-air intake.
     
    spidergoat, Jun 26, 2008
    #41

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  3. Syzygys

    Syzygys As a mother, I am telling you Valued Senior Member

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    Syzygys, Jun 26, 2008
    #42

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  5. spidergoat

    spidergoat pubic diorama Valued Senior Member

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    Latest tank:

    404.9 miles with 11.67G for an amazing 34.7mpg!!!
     
    Last edited: Jul 8, 2008
    spidergoat, Jul 8, 2008
    #43

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  7. Syzygys

    Syzygys As a mother, I am telling you Valued Senior Member

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    I am going to touch myself!

    By the way it wasn't a key cylinder problem, but something with the shift, the car didn't realize the shift was put into park and thus didn't release the key.

    This weekend I made 28 MPG but we got stuck in traffic and was using the cheapest gas. With 92 octane and without traffic jams I guess would have made 30+....
     
    Syzygys, Jul 8, 2008
    #44
  8. spidergoat

    spidergoat pubic diorama Valued Senior Member

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    I get stuck in traffic all the time. I leave a big space in front and find a steady speed, even if it's just a crawl. But you do have the automatic. I'll have to try that octane booster, but I thought that's just to prevent knocking.
     
    spidergoat, Jul 8, 2008
    #45
  9. Syzygys

    Syzygys As a mother, I am telling you Valued Senior Member

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    Once I should measure it when I get to do just highway with a decent trafficflow. If I stick around 65 MpH, it should get 32 or so, if not having 3-4 passengers....
     
    Syzygys, Jul 8, 2008
    #46
  10. DJ Erock

    DJ Erock Resident Skeptic Registered Senior Member

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    I've found that my car, a 2001 Impala, gets the best mpg around 70-75 mph. unfortunately, most of the speed limits around me are 50 or 55
     
    DJ Erock, Jul 8, 2008
    #47
  11. spidergoat

    spidergoat pubic diorama Valued Senior Member

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    Is it an automatic? It's probably because that's when the overdrive kicks in. Otherwise, the slower you go, the better the mileage.
     
    spidergoat, Jul 8, 2008
    #48
  12. Syzygys

    Syzygys As a mother, I am telling you Valued Senior Member

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    I kind of doubt that, because airresistance increases by the square with the speed.For most car the most economic speed is around 55-60 I think.
     
    Syzygys, Jul 8, 2008
    #49
  13. DJ Erock

    DJ Erock Resident Skeptic Registered Senior Member

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    Yeah, its an automatic. It's got a gauge that tells me the instantaneous mpg, so i've been on the interstate and used the cruise control to figure it out. 55-60 gets about 24, 60-65 is around 26, 65-70 is 28, and 70-75 is around 30
     
    DJ Erock, Jul 8, 2008
    #50
  14. spidergoat

    spidergoat pubic diorama Valued Senior Member

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    Sounds like it's the overdrive gear ratio, it allows the engine to operate at a more efficient rpm.
     
    spidergoat, Jul 8, 2008
    #51
  15. synthesizer-patel

    synthesizer-patel Sweep the leg Johnny! Valued Senior Member

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    don't try this at home kids - at least don't do what a mate of mine did - turned the engine off while driving, which then engaged the steering lock the next time he turned the wheel - D'Oh!
     
    synthesizer-patel, Jul 8, 2008
    #52
  16. clusteringflux

    clusteringflux Version 1. OH! Valued Senior Member

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    One click too far. Yikes!
     
    clusteringflux, Jul 8, 2008
    #53
  17. spidergoat

    spidergoat pubic diorama Valued Senior Member

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    I only do that when parking. I understand in modern engines if you coast while in a high gear, the computer shuts off the fuel flow completely.
     
    spidergoat, Jul 8, 2008
    #54
  18. Billy T

    Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    As thermal storage (of "cold") is free, that may be good idea when you would be using the break going down long hill etc. Running AC on "max" and "duty cycle" with less wear of the brake pads; but there are two concerns to consider:

    (1) the frequent use of the clutch that transfers belt power to or removes from the AC compressor may break it. (I am assuming there still is one.)

    (2) AC compresors may have problems with frequent turn on/offs. There needs to be time for any liquid of the "working fluid" (was a freon in my day) to get out of the compressor cylinder as piston can not compress that liquid. I assume there is some "extreme pressure" relief value, but do not know the details of what damage may accumulate if it is often active.
     
    Billy T, Jul 9, 2008
    #55
  19. Syzygys

    Syzygys As a mother, I am telling you Valued Senior Member

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    The AC takes away powers from the engine. When I go steep uphill I usually turn it off to help the engine....
     
    Syzygys, Jul 9, 2008
    #56
  20. Syzygys

    Syzygys As a mother, I am telling you Valued Senior Member

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    Just did vacation driving, 400 miles one way. Even using the AC most of the time and going 70+ MPH I got 33 mpg, I was rather impressed. I thought the faster speed would mess up the mileage. Basicly I made it to the target with one fill up....

    Coming back I put 89 grade into it thinking maybe I get a better mileage, but there was no signifficant difference....
     
    Syzygys, Jun 25, 2009
    #57
  21. Facial

    Facial Valued Senior Member

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    I first read about extreme hypermiling on Mother Jones (or was it Sierra?) magazine c. 2 years ago. There were experts doing 100+ mpg.

    According to the DOT the single most important influence on mpg has to do with the air filter. So if you get one of those modded race-car air filters fitted onto your car presumably that can boost efficiency.

    Tires, for hypermiling are at least 40+ psi.
    Passenger seats? Spare Tires? Rip 'em out.
    Tailgate large X-section vehicles.
    Coast downhill on neutral.
    Maintain 55mph or below.
    Press the gas periodically, and coast.

    With all of these, you can probably get above 40 mpg easily. There is also something with spark plug timing that can get a better efficiency, but maybe that's for older cars. My dad was able to tweak this 1970s Datsun to get 45 mpg instead of 25 by doing something with the spark plug timing.
     
    Facial, Jun 25, 2009
    #58
  22. Billy T

    Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I bet having a speed control or a very slowly changing pressure on the "gas" pedal is better than accelerate and coast. Where does this suggestion come from?
     
    Billy T, Jun 25, 2009
    #59
  23. Fraggle Rocker

    Fraggle Rocker Staff Member

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    No, that's an urban myth that was popular in many countries like the USSR. One of the worst things you can do for your fuel efficiency is to use your engine for acceleration. It's best to maintain a steady speed. Anticipate stoplights etc., to avoid excessive braking and resumption of speed, and if you are forced by circumstances to accelerate do it as gently as possible. With an automatic transmission maintain a low (but safe and courteous!) speed that's just fast enough to keep it in high gear, and avoid accelerating so hard that it downshifts. If you're on a hilly road or in city traffic, just do your best to use the throttle as sparingly as possible. With a stick shift keep the engine turning as slowly as possible without lugging; this may ironically require going a little faster uphill to avoid downshifting, which puts the engine into a different sector of its torque curve and burns more fuel.
    Another urban legend in the making. By twisting the distributor in an old-fashioned points-ignition, you'll set a world record if you improve your fuel economy by 25% and it's more likely to be 5-10% unless the engine was drastically out of tune to start with--I'm talking about pinging, balking, backfiring and smoking! There's no way you can double the gas mileage of an old car by merely adjusting the existing parts. Your father was doing something else, probably including a healthy dose of exaggeration.
     
    Fraggle Rocker, Jun 26, 2009
    #60
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