Questions tagged [efficiency]

Generally speaking, the ratio of how much work a component or apparatus does to the amount of energy or power it uses.

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Why do we still use catalytic converters? [on hold]

Catalytic converters catalyse substances which are no longer understood as environmentally hazardous. Carbon monoxide, hydrocarbon and nitrogen oxide are catalysed with oxygen. In effect catalytic ...
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Where and how is engine torque measured when producing an engine map?

An engine map - a set of curves of engine efficiency vs. both engine speed and engine torque - requires a measurement of both of those quantities. Where and how is engine torque measured to produce ...
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Compression ignition in petrol engines

First and foremost, this is not a question about reparing or maintenance. I'm familiar with how both petrol and diesel engines work, and I have a question about (possibly) making petrol engines more ...
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Could the OBD2 connector be used to switch gears?

What the title says, could I use an OBD2 code to control gear shifts in an automatic car? For example send an OBD2 code via a microcomputer like the Raspberry Pi. The car in question is a 2008 BMW e60 ...
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4answers
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Does a more powerful engine use less fuel for a specific load than a less powerful engine?

A colleague told me about a truck driving in the mountains. He said if the engine is too small, it would use more fuel to pull the truck up than if the engine were larger, noting the reason is the ...
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Could a wind turbine work for a car?

Could I attach a little fan to power a motorcycle alternator to be more efficient then running off the engine? Attach any where facing the wind on the vehicle to increase mileage from eliminating ...
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Ethanol or non-Ethanol?

Where I live gas is at $2.50 at 10% Ethanol at 87 octane and $2.90 for non-ethanol at 89 octane per gallon. I understand that smaller engines do not do well on ethanol. Is the loss of efficiency from ...
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463 views

Why don't automatic transmissions include Neutral in their range?

I have read the claim that modern automatic transmissions cut fuel to the engine on downhill stretches, thereby making it more fuel efficient to go down a large hill in drive than in neutral. However,...
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405 views

How effective is Italian tune-up? [duplicate]

I have a 2014 Suzuki Alto K10 Petrol (1000cc engine). The mileage so far has been fairly low <10k kms. The fuel efficiency is abysmally low ~8-9 kmpl. This average is running in strictly local ...
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Will I be better off turning the start stop function off?

I drive a 2017 VW Polo 1.0L. I use the car for primarily short journeys with the occasional motorway run. The car has a start stop function but I am skeptical of the benefits. Will it be a useful ...
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Is it possible to produce Fuel Efficiency graph using OBD2 app

Can the Torque app be used to produce a Fuel Efficiency graph for my car, or do I need a specialist for this kind of information ? Generally I want to measure the most fuel efficient extra-urban ...
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Trip computer gives inconsistent remaining mileage estimates

I own a 2017 Nissan Altima 2.5 that doesn't use ethanol gas. Its total mileage is 733. I've been on a trip for 2 hr 20 min. I've driven 135 miles for an average of 58 mph. My mpg is 36.4 according ...
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Is it more efficient to drive with the windows down or the AC on?

When driving, is it more efficient (in terms of gas consumed) to use the air conditioner, or to drive with all of the windows down? While the air conditioner reduces efficiency through drag on the ...
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Which is better when driving at 60 kph? [closed]

For a flat road with a maximum speed limit of 60 kph, which would be better for a 2.4L 4CYL i-VTEC gasoline engine (K24A4 rated at 160HP @ 5500 rpm, 218Nm @ 4500 rpm): 3rd gear at 2500 rpm 4th gear ...
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Is a gas car as sensitive to terrain as an electric?

Since I started driving a plug-in hybrid with a 50 mile electric range I've become sensitive to things that affect my 50 miles. For instance, when it's below about 40 degrees out I lose up to 25% of ...
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Results surprising said lab reporter of emission testing on Toyota Qualis Diesel 4 wheeler on AVL DiTest MDS 205

I got emissions of Toyota Qualis Diesel car tested with the AVL DiTest MDS 205, the result sheet had following columns rpm, temp, secs, CO(%vol.), CO corrected, CO2(% vol.), HC(ppm),HC corrected(ppm),...
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Wheel covers for MPG, recommendations

This is more of a pick your collective brain kind of question: I want to create wheel covers for my vehicle, a Civic VX, for increased MPG. I have done some research and what I have found are mostly ...
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How much can sub-optimal octane affect fuel economy? [duplicate]

Pick any production car that is factory-tuned for high octane fuel. We know that on lower-octane fuel it has to retard timing to avoid knocking. In effect, it has to run at a lower compression ratio....
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How much can sub-optimal octane affect efficiency or power?

Suppose a production fuel-injected engine is tuned for 93 octane fuel. As I understand it, the engine can still run on lower-octane (i.e., less knock-resistant) fuel, but it will pull timing to avoid ...
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What causes a 20% difference in fuel economy between winter and summer?

I've been keeping track of the fuel my car, a Ford Fiesta Ecoboost 100 hp, uses since the day I got it. In the last three years I've owned it, I've noticed a large (>20%) difference in fuel ...
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4answers
5k views

At what time of day/temperature should I refuel my vehicle?

I mean, should I refuel my vehicle in the morning? The reasoning is simple, in the morning the temperature is low and the density of the fuel would be higher and I get more energy per litre(or ...
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Is Tom Ogle's 100+mpg engine actually feasible? [closed]

I've just read about Tom Ogle, an inventor who claims to have built an fuel injection system that can achieve 100+ mpg and has apparently proven it, before dying in suspicious circumstances. From a ...
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Is there correlation between fuel efficiency and preferred gear at certain speed?

It may very well be just my imagination, but 3 months ago i decided i can do 30 miles per hour on 3rd gear and not shift to 4th. It didn't seam like the engine was under any extra stress or anything, ...
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256 views

Alternative fuel consumption metric to MPG to measure actual engine efficiency?

MPG is all very well and good, considering that most people that are concerned about their fuel consumption tend to want to get as many miles as they can out of it before they need to fill up again. ...
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Fuel Consumption Paradox

I've been trying different driving styles for a while now, in an effort to reduce my fuel economy and tank range. I've found that I get the best results when racing around, as opposed to driving ...
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256 views

What would be better for an engine driving at 60mph or 70mph? I wish to get the most miles out of my engine?

At 60mph my engine revs at 2800RPM and at 70 it's 3200RPM. My qustion is which condition would give the most miles from my engine.
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What non-driver, non-terrain factors can affect vehicle miles per gallon?

I've been tracking the mileage on my 2015 VW Golf (a non-intercooled turbo, but not diesel, thank goodness). Of course, my driving habits and highway/city balance influence things greatly, but beyond ...
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How can one calculate volumetric efficiency without a MAF sensor?

I am completely new in the field of OBD2 sensor; I am looking for a method (or a formula) to calculate Volumetric Efficiency of: Diesel Car Petrol Car which do not have a MAF sensor. Can anyone help ...
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612 views

Does using heat in the car SAVE gas?

Its well known that using heat in a car is almost free (see for example here). It is also known that using the heat can reduce the engine temperature which otherwise needs to rely on water cooling. ...
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How can I determine if it is more cost effective to run premium fuel in my car?

Every Time I fuel up my car, I collect my odometer reading, fuel price, and gallons pumped. A while ago I drove my car to almost empty and put 93 octane fuel in my tank, ran it to almost empty and ...
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Fuel Efficiency vs Engine capacity [duplicate]

How come there are cars with 1500cc engine producing with better fuel efficiency than a 800cc motorcycle with roughly the same amount of bhp? For example a Suzuki Splash with 1200cc and 87bhp returns ...
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Does the size of engine cylinder affect the efficiency?

I mean that, if cylinder have a design in which piston can change its working area alternate. Is there any chance to affect the burning ratio in loss or profit to efficiency?
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Will engine braking damage my transmission? How can I tell?

I drive a manual transmission '08 Honda Fit. On my daily 17 mile commute to work, there are three long hills that I can coast down, each about a half mile long. Going down these hills, I've done two ...