The myth of pulse and glide

Discussion in 'Fuel Economy' started by Chuck, Jul 11, 2009.


Has pulse and glide worked for you?

  1. Yes

  2. No

  3. What is P&G?

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  1. diamondlarry

    diamondlarry Super MPG Man/god :D

    Here is an example of results from earlier this week. These are ordinary trips for me doing ordinary everyday tasks and isn't even my best day either. P&G is my best friend.:) Don't tell me P&G doesn't work. It's too late, I already know better. And by the way, keep in mind this is a Prius and not an Insight. An Insight would be somewhat higher.
  2. R.I.D.E.

    R.I.D.E. Well-Known Member

    Doing far better depends on how you decide to cherry pick the math, as you did with your example.

    I posted here about a 2000 Insight that sold on ebay for $4000 with 128 k miles, one owner dealer maintained with a new battery and modules.

    That's $16,000 depreciation in 9 years, plus property taxes and higher insurance costs for a new car.

    $2000 per year before you spend a dime on fuel.

    I look at the total cost of ownership when I calculate the cost of transportation, not just the MPG, because that is money out of my pocket.

    Why did you sell your insight? Whats good for the Goose (your opinions of me) is good for the gander (my statements of fact that you seem to have problems comprehending).

    You won't see 140 MPG in my CVT, and I will back that statement up with a $2500 cash bet.

    All you need to do is drive it on the perfectly flat ground in the city of Poquoson Va. No cherry picking the situation to enhance your point, and no modification of the vehicle itself.

    Isn't that exactly what you slammed IamIam about when he referred to using battery alone to travel a few kilometers with no fuel use. The everyone here falls over themselves when someone posts they get 299 MPG, but don't bother to mention the other energy source they utilized.

    Smacks of an agenda to me.

    I do a lot of research and have a ton of real world practical experience. I don't worship any brand of auto. In fact (look it up yourself since you seem to choose to not believe) the air cleaner housing for a Tacoma pickup sells for $500!

    That's two pieces of plastic that couldn't cost more than $5 to make. Are you advocating just changing the party that screws you from the Arabs to the Japanese?

    Sorry I can't follow that logic (because it is not logic).

    Fuel mileage alone is only a small part of the cost of vehicle ownership. Personally I truly enjoy reading about new ideas as to how to get better mileage, and I appreciate your efforts to provide people with you exceptional knowledge in that aspect.

    What I don't appreciate is any denigration of my own intelligence which is the equal of any person here, or any sword of damocles thinly veiled threats or prejudiced assumptions based on the choice of professions I had to make a long time ago. That does not belong here or in any face to face discussion between people who have any respect for the capabilities of other people.

    This was a direct quote from Delta Flyr in a PM to me. If you advocate that interaction then practice what you advocate.

    You reply to the Lightening hydraulic hybrid with "That's interesting". You slam my idea with "It leaks".

    Why the double standard?

    IamIam stated that the problem with unsprung weight arises in a in wheel hydraulic drive. Charles Gray says I can hold a 500 HP hydraulic motor in my hand.

    Who is right?

    To assume my ignorance when you have no evidence to support your assumptions is something any reader can draw their own conclusions as to what that constitutes. I certainly don't need to define it myself.

    If you want to use examples of mileage that are 25 MPh averages in speed. that fine, but it is also what was done with the Opel 39 years ago.

    Why don't you buy an Opel, instead of a $25 k Prius?

    To me the total cost of transportation is the real point. I am sure that applies to many who post here. If someone wants to spend $30,000 to get 299 MPG, then that is their choice.

    The interest on that money will pay for my fuel.

    That's my choice.

    Which choice is better is irrelevant to the party who made the choice.

    Last edited: Jul 17, 2009
  3. diamondlarry

    diamondlarry Super MPG Man/god :D

    In case you haven't been reading any of the posts in here, let me remind you that parts of getting good mileage is planning and set up. As I have mentioned in posts in other threads, I once planned for ~ 1 week what the best route would be to get to a particular destination. Another one of those parts I mentioned is vehicle set-up. By not allowing Wayne to set up the vehicle and choose the route, the only thing you are going to prove is that your ways doesn't work. I don't understand your continued effort to refute things that have been proven to work by so many here and your reluctance (or should I say outright refusal?) to try them for yourself. I'm reminded of a quote that says, "If you want what others have you have to do what others do." It sounds a lot like, "If I can't make it work for me, it must be wrong/ineffective therefore I must try to discredit it."

    As for getting those high numbers and other energy sources involved, I can say that the battery level in my Prius from the beginning of a trip to the end usually only drops by a small percentage either direction. So, I guess the other energy source would be gravity/momentum/potential that has been very carefully managed by a proper P&G technique.
  4. R.I.D.E.

    R.I.D.E. Well-Known Member

    I am as great an advocate of P&G as anyone. I posted earlier in this thread about the technical details of why P&G works.

    Low manifold cylinder filling events (previous post) are the reason why BSFC charts show the dramatic increase in efficiency when P&G is used, but there are offsetting factors that limit the effectiveness of P&G, the greatest of which is the exponential increase in aero drag at the peak pulse speed.

    I try to explain things like that so people can understand why something is effective, instead of just reading a chart.

    I do not discount any knowledge without conducting a reasonable investigation that provides me with evidence to support or refute the claim.

    That's Due Diligence.

  5. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    RIDE, I wouldn't offer that bet too quickly. Wayne managed 146mpg at the 2007 Hybridfest MPG Challenge in Linda's CVT Insight.

    Link here

    Confirmation it was Linda's CVT Insight.
    Last edited: Jul 17, 2009
  6. diamondlarry

    diamondlarry Super MPG Man/god :D

    This is a good practice. I do this myself as well. If your results greatly differ with everyone else's results, do you ever consider that your research methods or techniques are flawed? I guess I'm the kind of person that won't let my lack of understanding of exactly how something works stand in the way of getting the results I want. I don't completely understand how the computer I'm using right now takes what I type and can send it out and have it end up on a site for others to read but, I'm not going to let that stop me from using that same computer to follow the techniques of others and achieve the results they get.
  7. diamondlarry

    diamondlarry Super MPG Man/god :D

    I wonder if he used P&G?
  8. diamondlarry

    diamondlarry Super MPG Man/god :D

    I forgot to mention above that the course Sean mentioned is not known ahead of time to any of the participants.
  9. R.I.D.E.

    R.I.D.E. Well-Known Member

    I agree exactly with the information provided. My only question is what is your average speed?

    To understand the point I am trying to make, think of it like this.

    Imagine everyone in your local area is doing exactly the same thing you are doing. Would that change your mileage.

    Being an advocate of efficiency is something my Pop programmed into me from birth. He was one of the people who computerized the Air Forces payroll operation using 4 k of memory in the early 1960s.

    What can you do with 4k of memory today?

    Looking ahead to the future of transportation means advocating methods and vehicles that can be applied to every single driver on the road, even the stupid ones we see every day.

    I was taught to blame the system, not the people. People who drive every day are not going to make the effort we put into mileage. That's why I advocate dramatic changes in the vehicles themselves. You would think that people who take the time to come here and learn how to drive more efficiently would understand that simple point.

    Trying to change the habits of the average driver is an exercise in futility. Advocating changes in the basic way a vehicle is designed, from it's initial cost to its lifetime per mile cost of operation while obtaining mileage averages at least twice as good as what is available today is the solution to our dependence on foreign oil for transportation.

    That goal should be pursued vigorously without regard to who it may cost in the short term. Presently almost every major corporate entity as well as the government has little vested interest in reducing the total cost of ownership because it takes money out of their pocket.

    That is very short sighted thinking, the type of thinking that will not happen in countries like China. They have the luxury of being able to look at our example and not take short sighted pathways to future evolution of transportation.

    We must compete with them to survive economically, and it will require us to make real changes in our long term strategic approach to transportation in general.

  10. diamondlarry

    diamondlarry Super MPG Man/god :D

    My average speed is usually 25-30 mph.

    From what I've seen in my area, my mileage would an upward/positive direction.
  11. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    My average speed is in the 22mph range on my commute and as with Larry, my average would go up substantially if everyone else drove the way I do.
  12. Chuck

    Chuck just the messenger


    90% of the drivers are not even going the speed limit, and that's not even considering hypermiling?

    So, if a light turns red 1/4 mile ahead, and it's a minute before it's green again, I should follow the crowd and keep on the gas even after I stop? Conversely, coasting with the engine off is disruptive?

    This poll does not scratch the surface of CleanMPG membership, but 40 state P&G has helped them, some for 3-4 years, how could so many be deceived? But then us Insight and Prius drivers are raping the Earth using those NiMH batteries more than tooling around in an H2. ;)

    Since hypermiling is too much of a behavior to expect, we should give up and continue to condone speeding? Give up on recycling and any green incentives? What did we do during WWII when resources were scarce?

    One more question: why is it people pay waaay more attention to how they do their jobs, knowing if they were as inattentive as many drivers I see every trip, they would be fired? I don't think you can say the average driver is paying attention.
    Last edited: Jul 17, 2009
  13. lightfoot

    lightfoot Reformed speeder

    On the highway, 50mph.

    It might improve my mileage slightly.

    People who come here and learn to drive more efficiently learn that they can make huge improvements without any dramatic changes to the vehicles. That has certainly been true in my case.

    If you think that you have missed the whole point of this website: it is an effort to demonstrate that present vehicles can achieve far more than the EPA estimates by modifying driving behavior rather than the vehicles themselves. Unfortunately, over the past 10 years most people have come to think that their car will "get" the EPA numbers no matter what they do while driving. Or that their driving behaviors will have only a small negative impact on the mpg. They need to see improvements >10%, preferably >20%, to be convinced that it's worthwhile to try driving differently. Showing them that it is possible is what we are doing here.

    We know that what we do works and have the data to back it up (see the mpg logs). Gary and Ian, if you expect your thoughts re hypermiling to be taken seriously you need to at least post your mpg data, as most of us do.

    Certainly folks here are interested in new technology and in speculations about things like hydraulic accumulators, batteries, and insulators, but not to the exclusion of doing whatever possible with the vehicles we currently have. Our results are quite good, so it's unlikely that we can be convinced to simply give up and place our faith in something that does not exist yet.

    All the discussions about total cost of ownership are rather tiresome because they hinge on projections of fuel costs (gas, diesel, or electric), resale value, and other imponderables (travel needs, driving habits) which are constantly changing. At best they are a guesstimate.

    If you want to be taken seriously as scientists, you need to follow the scientific method: propose a testable hypothesis, test it, and then publish the assumptions it is based on, the methods, and the resulting data for others to examine. Untestable hypotheses can be interesting but in the end are only idle speculation.
    Last edited: Jul 17, 2009
  14. diamondlarry

    diamondlarry Super MPG Man/god :D

    I'm beginning to grow very weary of this quite useless discussion so please excuse me if I'm a bit too blunt here. R.I.D.E. and iamian...please post some tank information and FE numbers. Kind of consider this a "Put UP or Shut UP" type of request. Thanks.
  15. R.I.D.E.

    R.I.D.E. Well-Known Member

    Filled up today. My previous logs are on gassavers forum for over a year, starting with my 94 VX with less than 30 k miles that I bought totalled and rebuilt. Thats recycling at its finest, and a good friend is driving the same car today, a car that was in a salvage yard to be disassembled for parts.

    614.8 miles
    8.522 gallons
    $19.42@2.279 per gallon
    72.143 MPG
    $.0316 per mile

    Lots of assumptions gentlemen. Msirach posted some dash photos earlier showing full tank mileages in close to the same range.

    One of those photos was 70.2 MPG for 650.5 miles averaging 57 MPH on the highway with 577 of those miles in one day with a 3 hour meeting in the middle of the day at Virginia Tech.

    You can look it up if you prefer to question the facts presented.

    Anyone who doubts my firm belief in P&G hasn't read what I posted earlier. I know how it works down to each cylinders combustion of fuel on an individual 180 degree power stroke basis.

    I know that the higher the effective compression of every power pulse the more efficient the engine. That means the actual compression measured dynamically when the engine is running at low RPM and with loads of 80% of maximum. In that scenario the efficiency is twice the average. Engine efficiency is perfectly matched to the actual volume of fuel-air mix that is in the cylinder at BDC of the combustion stroke, without full throttle enrichment.

    P&G worked in the 1970 Opel when they got 4 times the non P&G mileage averaging 26 MPH. Making claims without the average speed is the same as making mileage claims without a complete accounting for all the energy costs of the energy used to accomplish the mileage.

    The relevant facts please ladies and gentlemen. Is that an unfair request?

    My home power comes from a nuke plant 15 miles from my house and is carbon free. less than 900 KWH average (no natural gas whatsoever) per month for the last 3 months. My car is rated as a SULEV.

    I would speculate that puts me at close to the top of the low carbon emissions list ladies and gentlemen.

    Considering I bought the car used for a fraction of the new cost, pay less taxes on the vehicle as well as less insurance, and live in a home I designed to be energy efficient before the first shovel of dirt was disturbed, I am doing just fine thank you.

    What I do not do is come here and cop any greater than thou attitude and try to character assassinate others because I have some preconceived notion of their competence.

    Quite the opposite is true, I will gladly post information relevant to purchase decisions without bias or judgement. Many people here can not afford new cars, and while I can I still choose used because in the long run it is less expensive when all cost factors are combined as they should be.

    The bet stands, only restrictions are you can not violate any law or inflate my tires beyond the sidewall max, which is also a violation of law. You can not modify my car in any way that would void the remaining warranty, or operate it in any way that would cause excess wear or damage to the vehicle itself.

    I can do close to 100 MPG on this route (as I posted), but I doubt very seriously if you could do 140, considering the legal requirements posted above. I do not question Wayne's accomplishments, in fact I admire them considerably and have learned from his efforts. If he wants to try to do 140 with those restrictions I welcome the challenge.

    I can place the money in an escrow account tomorrow and provide proof of it's availability. The area where the test will be conducted has no traffic lights and a 35 mph maximum speed limit with very little traffic. The complete route from starting point to ending point is 9 miles with two stop signs out and one back.

  16. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Just asking -- where can I find a listing that states it is illegal for an owner to inflate beyond sidewall max?
  17. cpeter38

    cpeter38 Right Lane Dweller

    Let me be very clear - I AM an advocate of vehicle modifications when it makes sense. If it is going to affect your vehicle warranty, I doubt it will make sense.

    I also post real world results.

    I would strongly encourage everyone who is interested in improving efficiency/FE to do the same ...

    One other point, "practical" amounts of insulation is a perfect example of my understanding of technology. I understand that it is POSSIBLE to place 2 inches of insulation around a battery pack. It is also possible to place 1/4 inch of aerogel around a battery pack. However, it is doubtful that a manufacturer will be able to afford the packaging (foam) or material(aerogel) cost and still deliver the vehicle at a price that is perceived as "affordable" by most customers.
    Last edited: Jul 17, 2009
  18. R.I.D.E.

    R.I.D.E. Well-Known Member

    If you are in an accident and the accident investigator finds that your tires are inflated beyond the manufacturers recommendations as well as the tire manufacturers posted maximum pressures, that information could have an effect on the court proceedings.

    I have driven a Scion XB that was overinflated by the dealer to 65 PSI instead of the sidewall max of 44 PSI. The ride home was horrible. The dealer had added optional wheels and those very low profile tires that could be inflated to 65 PSI without any legal difficulties. The tech inflated the stock tires to the amount that was correct for the low profile tires but wrong for the stock tires. I told them to replace the mags wheels and low profile toires with stock steelies and stock tires becasue I did not want to pay an additional $1800 for the rims and tires.

    Now lets assume one of my tires blew out on that trip back to my house. I would have a legal recourse due to their negligence to be compensated for damages caused by their neglect. The tire manufacturer would have no liability since the tire inflation max pressures were ignored, but the dealer would be sued by me.

    Operating your car in a way that shows you do not consider posted maximum pressures to be of any relevance constitutes neglect, and leaves an evidentiary trail.

    Since I have the assets to encourage a lawyer to go beyond the maximum liability limitations of my insurance policy, I have to consider any potential situation where my actions could be interpreted as neglect, regardless of the infinitesimally small chances of that ever happening.

    Legal or illegal, that's your individual choice. I chose to err on the side of legal. I also choose to not have a rattletrap with 50 k miles due to the beating a car takes when tires are severely overinflated.

    Many laws are written to be ambiguous with wide variances in interpretation.

    In my opinion (only mine and no judgement of others opinions) it is not worth the risk, or the long term damage.

    Sidewall max for me.

    Choose your own maximum at your own risk, but it could certainly be legally interpreted as reckless driving. You opponent has a better lawyer and a sympathetic judge and you get screwed.

  19. R.I.D.E.

    R.I.D.E. Well-Known Member

    I respectfully disagree.

    There is a distinct window of opportunity in timing lights, even if the light has no obstructing traffic to cause you to have to slow down. The more people who are doing exactly the same thing in light timing the less room for every driver to do the same without tailgating.

    Many of the lights I time daily are only green for 15 to 25 seconds, in an almost 2 minute full cycle. That only allows a certain number of people to be in the perfect position to hit that light when it is green. The more cars you add into the equation the smaller the available space for the perfect light timers.

    In some cases on left turn only lights there is only enough green signal for 5 cars to clear the light.

    I try to catch the light in the last 25% of the green cycle. If I hit one yellow I can either slow down immediately or speed up slightly to catch the next timed light green. The car behind me will be all over my rear end if I started to slow down to time the next light for the next cycle and that driver could loose his timing if I did not increase my speed for the next light.

    22 lights in 20 miles and in many cases I can catch only one. Some of them (probably 25%) are triggered by arterial roads and not timed at all. Those are the ones that usually cost me inertia. In one segment the lights are less than .2 miles apart so trying to time them is always a gamble. I wish they would coordinate the timing so the main road traffic always had a priority but that is not the case presently.

    My best ever effort was 42 miles and somewhere near 60 lights without stopping completely for a single one, but that is very rare with tripped arterial lights that can catch you completely randomly.

    If we all drove down the interstates at 45 MPH (posted minimum speed) then the volume of vehicles on a given distance of road would increase proportionately to the average speed of every vehicle. The only solution would be to decrease following distances and increase the risk of accidents.

    If you average 70 MPH for 700 miles you are on that road 10 hours. The time doubles if you average 35 MPH and congestion would double unless following distance were cut in half.

    In many cases if you are there at the wrong time on I64 from Richmond to Hampton Virginia, the traffic is bumper to bumper at 72 MPH. If you allow a reasonable distance between you and the car in front of you other drivers will just pull over two car lengths in front of you. You also cause whiplash brake applications for a half a mile behind you if you do not maintain a speed consistent with the other traffic.

    Fortunately there are parallel older US routes that have virtually no traffic and slower speed limits. I usually chose the less stressful option, but when there is road construction I will jump back on the interstate and go with the flow. Now I know we do not advocate drafting bu in the specific scenario it is unavoidable and I can actually maintain almost exactly the same mileage with a 10 MPH increase in speed, but it certainly is not anything I would call an enjoyable drive.

    There are areas where I live where 50,000 cars pass over the same spot in a single lane of highway over the Hampton Roads bridge Tunnel and other places. With 86,400 seconds per day that is less than 2 seconds per car 24-7. In many time periods its less than 1 second per car and very dangerous with a single mistake creating a chain reaction of collisions.

    With average speeds of 25 MPH 24-7 at that point in the road you would require separations of half the distance at the higher speed. The typical afternoon backup is 7 miles and in some cases it will easily exceed 20 miles.

    There are times like that that I just avoid that area altogether.

  20. Shiba3420

    Shiba3420 Well-Known Member

    I'd actually agree with Right Lane Cruiser, but agreeing or disagree will depend largely on where you drive and how. I have to admit to driving faster than I'd like based on automotive peer presure. I won't break the speed limit, but there are times, I'd like to be going 10mph slower, but I know it will anger traffic behind me even if it works out well for everyone. Its in these cases I could save gas. However, your drive may be more light to light where there is far less effect. As they always say....your mileage may vary.
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