Driving technique for braking in the city

Tips, advice and tips to lower your consumption, processes or inventions as unconventional engines: the Stirling engine, for example. Patents improving combustion: water injection plasma treatment, ionization of the fuel or oxidizer.
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Did67
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by Did67 » 07/06/08, 17:47

nlc wrote:
For fuel: on my vehicle it consumes less in engine braking, since no more drop of gasoline is sent. While stalled, though, because of slow motion. I think it is the same now with all recent vehicles, gasoline or diesel (but I'm not sure).


Indeed: on all sequential injection gasoline engines (often an i in the 1.4i genre designation), the quantity of gasoline injected is continuously calculated as a function of demand (accelerator pedal, speed, lambda sensor, etc. ..). When you use the "engine brake", there is no fuel injection, while when disengaging, the engine runs slowly and we consume! This can be seen very well if you have an on-board computer that displays the instantaneous consumption: you take your foot off the slope, and presto, it displays 0!

If in doubt: open the hood. If you see a good old carb, it's not multipoint injection. In this case, we will see small injectors, fed by a small gasoline line, on the intake manifolds (all carefully hidden under plastics which "look" the engine).

Ditto for modern diesel engines with calculator (all direct injections, but also many TDs that are already 10 or 12 years old).

So, in this case, to save:

1) Above all, do not disengage !!!

2) But to anticipate et lift the foot : the ideal would be to lift your foot early enough (and therefore drive with a consumption 0) to arrive at the obstacle (turn, stop, growth, entry into town) at a speed low enough to no longer have to brake or very very little !

Two additional remarks:

1) Contrary to what we think, we hardly waste time !!! On a 20-minute journey (my home-work tarjet), between driving the most "speed" possible and the most economical, on average, less than a minute of difference!

2) On the other hand, I "scratch" more than 1,5 l per 100 km of consumption on average.

I recently had a car with a computer that allows me to record all of this, it's very impressive.

Hence the rule: "to brake is to consume !!!"
Do not divert and make accidents by refusing to brake. But use in anticipation: entering the city at 250 m, I lift my foot and I arrive almost point-blank at 50 km / h on the spot !!!
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Philippe Schutt
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by Philippe Schutt » 08/06/08, 00:29

In consumption you consume 0 but you slow down quickly.
In neutral, you consume very little, and you hardly slow down.
the result is undoubtedly very similar.

If I don't have to slow down, I prefer the PM, if only for the noise.

Finally this poses a question (absurd?). on the motorway, if instead of driving at constant speed alternating accelerations and freewheels, would we consume less? Image
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by Did67 » 08/06/08, 11:06

Philippe Schutt wrote:
If I don't have to slow down, I prefer the PM, if only for the noise.

Finally this poses a question (absurd?). on the motorway, if instead of driving at constant speed alternating accelerations and freewheels, would we consume less? Image


Indeed, I was in situations where "at the end", I have to slow down or stop. Excluding motorways and expressways, this already represents quite a few situations. I think 1 to 1,5 l / 100 km to scratch!

Noise, on my "exclusive" C5, I hardly hear it. If: rolling noise, depending on the coating. There, the dead point is useless!

I also have a descent with 4 or 5 turns. There too, I roll on inertia, in 4th, with one foot off the ground and I save braking when entering each bend and "scratch" a little more ...

On the other hand, intuitively, I don't think your last idea is good. Life being badly made, somewhere there must be old principles of thermodynamics which must play: I think that it costs you more to start again than you save by slowing down. Otherwise, it would be something like the invention of perpetual motion !!! It would be enough to put a big wheel with inertia, and presto, you accelerate, you slow down 50 times and hop, you roll with the eye ... Alas, I do not think that that works !!!

On the subject (motorways), since I have my C5 on-board computer, I am impressed by the impact of speed on consumption. I thought it was a bit of an exaggeration, the stories of reducing speed in the event of pollution. A technocratic joke short of real measure. Not at all !!!

I did not note, because I was driving but on a flat section of highway, I tried, with my cruise control (speed stabilized). Basically, from memory: at 90 km / h stabilized, about 5 l to 5,5 l per 100; at 110 km / h, around 6 to 6,5 l; at 130 km / h, it's 8,5 l !!! (C5 2.0i 16 V petrol therefore, converted to LPG - these are the theoretical petrol consumptions given by the computer; with LPG, the 7,5 l of petrol displayed therefore therefore theoretical becomes 8,5 l of real LPG at the pump - sequential liquid injection of LPG). The small variations are micro-relief, which we don't even realize. The C5 is heavy and it feels immediately for instant consumption.

So unless there is an emergency, I now settle down around 110 km. I was also surprised to note Sunday evening that on the sections at 130 m / h, we were a majority to drive at 110 km / h!
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by georges100 » 08/06/08, 15:05

how did you not know ???? you never noticed that your stationary car consumed very little ???? : Cheesy:
without joking consumption is not linear with respect to speed, the faster you drive the more you consume but the last km / h cost a fortune : Cheesy:
the economic cruise, the best speed / autonomy ratio is around 70% of the engine power (André I see you coming with your variable steps : Cheesy: )
if you have driven 2CVs you have noticed that at constant high speed they are sinkholes ... proportionally at the same speed a ferrari will consume less, the engine being less stressed ...

I have 2 identical cars apart from the injection pumps and they do not have the same behavior ... I know them well and I know at what speed they feel good, that is to say that it runs without force gently, and that must correspond to the economy ... well these speeds are not identical ...
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by Other » 08/06/08, 15:51

Hello
(André I see you coming with your variable steps)
if you have driven 2CVs you have noticed that at constant high speed they are sinkholes ... proportionally at the same speed a ferrari will consume less, the engine being less stressed ...

for propellers it is another subject if you need information I have a long experience in this field
the 70% of the power is not as sharp as it depends on the aerodynamic quality of the car, the size of the engine and especially the type of gearbox and bridge, of the vehicle
On a Camaro one at 100kmh a 4 cylinder is more fuel efficient than a 6 cylinder
and at 140 km / h a 6 cylinder is more greedy than an 8 cylinder
the only place where the 4-cylinder is favorable is city driving with many stops.
It is true that the guy who has a V8 at the back he tends to shoot the horse at acceleration.

For the planes the economic regime it is a small propeller with big step and low RPM, 2200 that makes wheelbarrows which run at takeoff and that it is necessary to wait which want well mounted
unpleasant, is risky in the Bush.
It is the same with the cars the manufacturers pose transmitions to have cars which have a good accelleration that is part of the selling point, even if it is contrary to consumption.
the fuel has increased .... Just go to traffic lights in town and observe the behavior of the drivers
nothing has changed, it will not change even if the fuel doubles .. Normally starts at a traffic light it pushes backwards and you see the driver's lips go and not always caps upside down ..

Andre


With water doping on a 300D it is more economical at 100kmh than at 60kmh
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by georges100 » 08/06/08, 16:12

in fact we say the same thing andré : Cheesy:

in canada i don't know but in france driving schools have a big responsibility ...
when my niece passed her license I was scared !!!! downshift from 5 to 3 while making the engine roar, roll in 3 on the access to expressways "to have recovery", crush in front of red lights ....
obviously the pipe casting they don't know : Cheesy:
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by Did67 » 08/06/08, 18:08

georges100 wrote:in fact we say the same thing andré: cheesy:



OK guys ... I talk to normal people, sometimes it helps them. You know a lot, you, people who drive in Camaro and wonder if a V8 is more economical than a V6, but not in town ????

What I know is that in standard consumption, the same car (the C5 for example, which I studied, because I had an offer for a V6 at an unbeatable price), consumes significantly less with a 4 cylinder 2 l than with a 6 l V3. I also know that to go below the 3 l mark, Volkswagen has equipped the Lupo with a 3 cylinder specially developed for this. Less cylinder = less moving parts = less losses!

After, Camaro, not variable ... I don't know.

I am not TOTALLY a Boeotian, I know that consumption increases with speed! I wrote that I didn't realize it did much ! The on-board computer used as driving assistant enlightened me on this subject ... This naivety there, I want to recognize it. And I don't even think I'm the only one, hence the fact of having put this reflection online.

Afterwards, I leave you among yourselves, with your stories that only you can understand! In any case, not many, I suppose ...
Last edited by Did67 the 08 / 06 / 08, 18: 16, 1 edited once.
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by Flytox » 08/06/08, 18:14

Hello Philippe Schutt
Philippe Schutt wrote:
Finally this poses a question (absurd?). on the motorway, if instead of driving at constant speed alternating accelerations and freewheels, would we consume less? Image


This principle is used for vehicles with record consumption at the Shell Marathon. The difference is that the vehicle is very under motorized. A kind of down-sizing which means that the engine is used fully during acceleration, to have an excellent performance, and once the "optimum" speed has been reached, they cut the engine and coast forward until reaching the maximum speed. lower speed limit and then the cycle begins again.

https://www.econologie.com/forums/pantone-et ... 53-10.html

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by georges100 » 08/06/08, 18:20

don't get mad : Cheesy: It is not because oil increases that we can no longer laugh : Cheesy:

give it a try with your computer it must be easy, but watch out for the radars : Cheesy:
and you will see that at a certain speed (therefore speed if you do not change gears and on flat) your instant consumption will explode ... this speed is variable depending on the cars ....
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by Other » 08/06/08, 18:46

Hello

Jen don't know your cars, I took an example that I know well
with cars around me.
A Camaro or a Buick or a Chevrolet is very ordinary large series cars.
But I suppose that all cars have an economic regime and that when we drive under this economic regime it consumes more

In 5th at 60kmh it risks saving more than at 100kmh
that's just what i meant ..

Andre
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