New answers tagged

4

A lot of that depends on the type of vehicle, and your definition of 'fast'. Take this with a grain of salt, but a while back BBC's Top Gear did a test involving a V8 powered BMW M3 and a Toyota Prius. The Prius was driven as fast as it could go around their test track, while all the M3 had to do was keep up. After a few laps, the Prius had done ~18 mpg, ...


5

In a perfect world from a physics textbook, you might be able to ask the question you have, and expect to compare time vs. engine speed, but there are many more factors in the real world. The speed-agnostic measure is Miles Per Gallon (or l/km). Speed doesn't appear in the name, because it doesn't matter. At higher speeds, things like wind resistance and ...


0

Your belief is in alignment with how older vehicles(without engine control units) work. You need to understand "Overrun" condition:A condition in which vehicle drives the engine. Refer Mr Cholmondeley-Warner's answer. Keep in mind,engine movement must not stop. It should be either driven by fuel or by vehicle momentum.Or else we need to crank again to ...


1

Issue got resolved in next service. The problem was the with the rotor. Front wheel rotor was touching the caliber causing too much resistance. On close observation it seemed that rotor its shape after a bike fall lately. Replaced it with a flat new rotor and was able to drive 420 kms in full tank.


0

There is an additional reason for not running lean, which applies very well to turbocharged engines - the extra fuel creates a 'boundary layer' between the combustion products and the cylinder wall. This absorbs extra heat during combustion to help keep the chamber temperature within tolerance. Modded cars that run very high turbo/supercharger boost are ...


6

Lean operation vs exhaust catalysts: The three-way catalytic converter fitted to gasoline vehicles can't operate under lean engine conditions because the reaction of NOx to nitrogen and oxygen is a reduction reaction, and for this to occur there needs to be a corresponding oxidation. In the three-way catalyst that is the oxidation of CO and hydrocarbons to ...


2

Running a lean mixture by itself isn't necessarily going to cause detonation, pinging or knocking. WW2 era old timer piston aircraft pilots used to run seriously lean mixtures on long hauls to increase range and it was safe to do so when they were at cruising altitude and power settings. You'd never consider doing it in a climb or at a high power though. ...


2

One additional point to touch on is that leaner and richer are relative to what conditions the engine already runs under. In terms of chemical reactions, car engines tend to run a little rich by default -- more fuel than is needed for all of the air -- because it reduces the frequency of detonations in the mixture. If you alter things so they run leaner ...


17

Lean ≠ More Air I believe the source of the misunderstanding is in how the term "lean" is being interpreted. A lean mixture doesn't indicate the presence of more air. It indicates the presence of a higher proportion of air compared to fuel (air-fuel ratio, or AFR). Quick example Mixture A has 1,000 g of air, 80 g of fuel. AFR = 1000/80 = 12.5 ...


8

It's not that the catalytic converter can't handle more air per se, it's that running lean increases the temperature of combustion (I actually don't know why, but now I'm curious) and the catalytic converter needs to run inside it's chemical operating range. Something to do with the chemistry that I also don't know. As for advantages for turbo boost and ...


3

The EPA (US - Environmental Protection Agency) lists the mileage for this car at 27 MPG City, and 37 MPG highway. That's roughly 11.47 Km/l city and 15.73 Km/l highway. Granted, these ratings are under absolutely perfect conditions so they are a fantasy when it comes to real world combined mileage. So let's call it a combined of roughly 26 MPG which is 11.05 ...


5

There is Brake-Specific Fuel Consumption Which is a measure of how much fuel is consumed per unit energy. Another way to look at it is the rate of fuel flow needed per unit power developed by the engine. This information is not something accessible through OBD-II. But it's not very useful in this case Note that MPG remains relevant because it is a ...


5

Just so we're on the same page as to how two strokes work, here's a pic. I had to look it up because I had the wrong picture in my head. In looking at how the cycle actually works, the power stroke goes off creating the combustion products and power. As the downstroke begins the pressure in the cylinder is high allowing the exhaust gases to escape and ...


0

Take a look at how a 4 stroke engine works. a) Downstroke - sucks mix into the engine b) Upstroke - compresses gasses c) Fire d) Downstroke - engine does Work e) Upstroke - used gasses are expelled Now look at the 2stroke a) Fire b) Downstroke Engine does work (high pressure in cylinder) Compresses mix in crankcase c) Upstroke - ...


4

Lower "cold side" of the Carnot cycle leads to better theoretical efficiency, sure, but have you calculated how much? 10-20 K colder intake with the same 1000 K combustion temperature affect final efficiency by 1%. And that efficiency is 70% in any case, so you can guess that there are so many more parameters lowering the final efficiency to 25%, that the ...


3

I have to both agree and disagree with your statements in the question and the article. The higher fuel consumption of a two stroke engine is mostly due to the fact that it has a power stroke per revolution of the crankshaft. I however have to disagree with the article stating that the fuel delivery plays a major role in fuel efficiency of older 2-Stroke ...


5

BSFC is just engineer-speak for how much fuel is consumed by the engine per unit of energy output¹. This webpage provides a very concise comparison for several different engines: +------------------------------------------+----------+----------------+-----------+ | Engine | @ 1K RPM | @ Peak Torque | @ Peak HP | ...


2

Yes, provided the following conditions are met: the units for the values MAF and fuel flow values are consistent. if you're using OBD-II parameters the values are usually in different units. In fact, fuel flow is usually volumetric (L/hr) and not mass flow like the reading from the MAF so you would have to correct for that by injector flow rate, I'm ...


1

I want to share my fuel consumption story....I have a second hand Suzuki Ignis 2002 1300cc. When I first got it in 90.000km the gasoline consumption was 7.2lit/100km. Suddenly the consumption raised to 11lit/100km. Also I had a lot of emissions. No strange lamps on my dashboard... Everything normal except the consumption and emissions. My mechanic, serviced ...


0

When activated, ECON mode alters the Drive-by-Wire throttle system response curve in the range from about 10 percent to 60 percent of throttle pedal travel. With less gain, the throttle opening in this range increases more gradually to reduce a potentially excessive peak input for improved fuel efficiency. ECON mode also alters the operation of the cruise ...



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