# Questions tagged [fuel-economy]

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### Which is fuel efficient, roadways transport vs waterways transport? [closed]

Which will be more efficient in term of fuel price: Transport via roadways, say truck or motor vehicle. Transport via waterways, say via ship or motor boat. Assumptions: Same caliber engines (same ...
40 views

### How to Calculate Approximate Fuel Consumption from Engine Specs

I have a marine diesel engine, and I'd like to calculate the approximate fuel consumption based on the size of the engine, at a given number of RPM - specifically for the cruising recommended cruising ...
6k views

### How can "mpg" be high under low engine load?

Let's say a car at 60 mph requires roughly 20 hp to maintain its speed (i.e., to overcome rolling resistance and drag). If this car makes 240 hp and gets about 34 mpg (not too unrealistic), how is it ...
395 views

### What does MM prefix mean in MMtoe?

I was reading documents about energy importation and came across the following: The import was of 5,915.87 MMtoe I wonder if MMtoe = $10^6*10^6$ toe = $10^{12}$ toe. First time coming across a ...
4k views

### How does turning off electric appliances save energy

We all know if we use less electricity we save energy. But the energy we're getting is result of burning (not necessarily the literal meaning) the fuel. Even if we don't use that energy that fuel is ...
34 views

### Where can I find efficiency metrics for diesel engines?

I am doing long term planning for a small fleet of tugboats. A lot of the engines (propulsion, generators, hydraulics) are Detroit Diesels of various sizes (e.g., 4-71, 6-71, 12V-71). Newer engines ...
87 views

### Can we currently achieve 55 MPG on Non-Hybrid vehicles using internal combustion engines?

With recent debates, one frequently hears that it's currently not possible for car manufacturers to meet the 55 MPG energy efficiency rating required by 2025. So, is there something physically ...
58 views

### Does the shape of a car really matter for how much gasoline it drinks?

Let's say that we have a mid-1950s "gas guzzler". Now, we take away the exterior "shell"/chassis and replace it with a modern car's. That is, it will visually look just like a modern car from the ...
68 views

### Can turbine engines really run on "just about anything"?

I often read that turbine engines can run on almost any fuel source. I understand that turbine engines are less "picky" in terms of the fuel source that they can use, but surely there would still be ...
29 views

This may be difficult to answer but, theoretically, if you had a car with a sterling engine that produces say approximately 300 horsepower how much of any specific heat source would need to be used if ...
1k views

### Whats the purpose of a main metering system in a carburetor?

I'm confused on how to differentiate mixture control from the main metering system, and why we even need one at all. Let's say we had a large resovior, and a needle type mixture control system. The ...
4k views

### Why wont Petrol engine run on Acetylene?

Boiling temperature of Acetylene is -84°C and that of Petrol is 95°C (at Atmospheric Pressure). So the spark is efficient to ignite the compressed Acetylene and run the Engine. But why wont that work ?...
99 views

### does payload weight distribution affect rolling resistance?

Recently came across the following 2-minute YouTube video that claims A Balanced Rig Saves Fuel While nicely done, it is a marketing video. Does anyone know of any unbiased studies that support the ...
115 views

### How much air will an engine use per tank of gas?

Apparently I have a stupid question. I got curious and crunched some numbers to determine approximately how much air an engine consumes in total to burn a full tank of gas. Something went horribly ...
261 views

### Best fuel for supercar engines

To experienced supercar owners/engineers: What is the best fuel for a turbocharged 6 liter V8, 7.6 liter V10, or 9.2 liter V12 (Audi R8 or Lamborghini Aventador type cars) in terms of speed/...
79 views

### seperate engines working vs single engine [closed]

Assuming we have 2 identical cars. What is the total energy consumed by the two cars to start and accelerate up to a specific speed versus the total energy for one of them to accelerate up to a ...