Questions tagged [engines]
68 questions
13
votes
8 answers
Is there a reason (in terms of the physics involved) why it is better to push start a car in 2nd gear rather than 1st?
I am struggling to understand why it is recommended to push start a car in 2nd gear rather than 1st - in terms of the physics involved, I fail to see a reason why this would be the case. I have compiled where I am at currently with a for/against…
PhysicsGuy123
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10
votes
2 answers
Are small car engines designed to tolerate a higher duty cycle than large car engines?
For simplicity we're going to ignore aerodynamics and vehicle mass for a moment...
Are small (around 1 litre) car engines designed to tolerate a higher duty cycle than large (2+ litre) car engines?
Cars are usually all travelling at roughly the…
squigbobble
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9
votes
5 answers
Why do some diesel engines run on diesel fuel and others on fuel oil?
Trucks and smaller vehicles with diesel engines run on diesel fuel which looks more or less like kerosene - less flammable than gasoline, low viscosity liquid. However larger diesel engines like this 120 thousand horsepower marine engine have more…
sharptooth
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7
votes
2 answers
How efficient are jet engine thrust reversers?
Most reasonably sized commercial aircraft rely on jet engines for propulsion. Upon landing these aircraft use a number of means to come to a stop with the two most important being (I believe) mechanical brakes and jet engine thrust reversal. This…
Chris Mueller
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6
votes
2 answers
Limitations of the cut-off ratio in real-world diesel engines
In an ideal diesel cycle, the cut-off ratio is set by the maximum gas temperature after combustion. That's all fine and good, but in a real-world engine what controls the cut-off ratio, and what are the limits to its flexibility? I feel like it must…
Murenrb
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6
votes
1 answer
What makes crosshead bearings hard to lubricate?
Regarding crosshead bearing failure, I have read that at slow speed it is difficult to establish a lubricating film because there is an imbalance between forces due to combustion and forces due to inertia. This information is from a maker of big low…
veronika
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5
votes
1 answer
Alcohol as a working fluid?
Alcohols with their lower boiling point and overall non-toxicity, could they be used as a turbine working fluid instead of steam water?
LazyReader
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4
votes
3 answers
How many power strokes per rotation in a 3 cylinder engine?
How many power strokes occur for every complete rotation in a regular 3-cylinder engine? Or in other words, every how many degrees does a new power stroke takes place? Does anyone know please?
ergon
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4
votes
1 answer
In a diesel engine, does more heat leave the engine through the tailpipe or the radiator?
Diesel exhaust is hot, and there's a lot of it.
Diesel radiators also get pretty hot.
In a typical diesel engine, which one is dissipating more heat?
EDIT: In response to a request for specificity below, I am specifically interested in heat losses…
Diogenes Creosote
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3
votes
1 answer
In internal combustion engines, what determines when soft or hard gaskets are used?
I see that 4 stroke engines use hard gaskets at the cylinder heads, whereas two stroke slow speed engines that are used for the propulsion of ships or for production of electricity on land have soft gaskets.
What determines which gasket should be…
veronika
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3
votes
2 answers
Why is soot produced in diesel exhaust, since diesel runs lean?
Since diesel runs lean, why is soot produced in diesel exhaust?
Soot is carbon particles due to incomplete combustion. But, since diesel runs lean with plenty of oxygen, why does this happen?
ergon
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2
votes
1 answer
How Scalable is the Wave Disk Generator Engine
How scalable is the wave disk generator engine? Are there fundamental limits to how large or small the engine can be and if so, what are they? I'm not looking for answers addressing microscale issues, but rather, I want to know if the fluid…
Brinn Belyea
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2
votes
1 answer
How friction between stator and rotor is dealt with in an electric engine/motor
This YouTube video https://www.youtube.com/watch?v=nlG2dsYRagI shows how an electric engine is made but I don't understand how friction between the stator and rotor is dealt with.
At 3:50, we see the rotor inserted inside the stator and at 4:32 we…
Aminos
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2
votes
1 answer
Out of the three types of Stirling Engines, which one is the most efficient and delivers the most amount of power?
I was thinking that the beta Stirling engine would be the most efficient as it has a displacer to block heat transfer from the hot to cold regions in between thermodynamic cycles. However, I heard that the alpha engine has the best power-to-weight…
ARJ
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2
votes
0 answers
Calculating engine pressure from measureable quantities
How can I calculate the engine pressure in units of Bars by using torque, the cylinder volume, motor efficiency, and the gear reduction ratio?
My values are as follows:
Torque = 1063 Nm
Hydraulic Motor Cylinder Volume = 2.56 ℓ [litres]
Gear…
3kstc
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