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Questions tagged [engines]

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28 views

When does the minimum temperature in a four-stroke cycle occur inside the engine cylinder?

I've checked on quite a few places on the net and some say it occurs at the beginning of suction stroke and others say at the end of suction stroke. I believe it to be at the end of suction stroke ...
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1answer
15 views

Relationship between Heat Flux and Engine RPM

I'm doing a project that involves knowing the average steady-state heat dissipation rate of a single cylinder air-cooled engine (through the engine wall and fins) at a given RPM. The problem is that I ...
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1answer
22 views

What developments made diesel engines suitable for personal cars in the 1970s/1980s?

Both diesel and gasoline engines were developed in the late 19th to early 20th century. Diesel engines were for the most part of the 20th century used mostly for large applications in ships, trains, ...
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1answer
33 views

Effect of Pressure on Combustion efficiency (of hydrogen) in excess air

Can somebody explain relation between combustion efficiency and pressure in lean mixtures using any kind of chart or mathematical equations? At first glance I thought, combustion efficiency increases ...
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2answers
40 views

How do turboshaft engines maintain a constant rpm regardless of load?

I understand that most turboshaft engines tend to run at (or close to) their most efficient rpm all of the time, and it is the load that is changed e.g. the pitch of the blade pitch on helicopters. ...
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1answer
49 views

What are the non-practical features of a sterling engine that cause the internal combustion engine to be used instead?

What are the non-practical features of a sterling engine that cause the internal combustion engine to be used instead (in a car)? (e.g. price, size, the power to weight ratio, etc.) Can you name any ...
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0answers
15 views

Efficiency of a sterling engine

What is meant by thermodynamic efficiency of a sterling engine? and what are the factors that affect the thermodynamic efficiency of a sterling engine? Similair to other questions i know despite ...
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0answers
23 views

PLEASE ANSWER Sterling vs Combustion Engine

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 ...
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3answers
29 views

Efficiency of an engine

What is meant by thermodynamic efficiency of an engine? and what are the factors that affect the thermodynamic efficiency of a diesel engine?
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2answers
125 views

How do external irreversibilities decrease the efficiency of thermodynamic cycles?

In gas power cycles, one mentioned that: The Carnot cycle is both externally and internally reversible. Therefore making the Carnot cycles more efficient than other practical cycles. Question: ...
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2answers
101 views

How difficult would it be to build an entire engine (block and all) in 16th century conditions?

I was ruminating over A Connecticut Yankee in King Arthur's Court. In the book, a trained American engineer goes back in time and creates guns. The book itself predates tanks, but one could imagine ...
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3answers
50 views

Inlet of an ICE [closed]

What is wrong with totally replacing the inlet of a piston engine with a surgical mask?As surgical masks get rid of about 80% of air impurities and dusts.
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3answers
590 views

Manual transmission: Why downshifting is less smooth than shifting up?

Today while driving I had to make a quick shift to a lower gear that was not as smooth as it should've been. I've been taught that while shifting to a lower gear you have to be more careful when ...
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1answer
821 views

What is Inlet-valve Mach index?

What is the meaning of this statement "In a reciprocating engine the flow of intake charge takes place through the intake valve opening which is varying during the induction operation. Also, the ...
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0answers
211 views

Detergency and dispersancy

Abstract:The detergency property in oil comes from a chemical additive called detergent which has a property of preventing the deposition of carbon deposits and wash it away. There is also this ...
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1answer
141 views

What's the slowest airflow speed a ramjet could work?

Thinking experiment about a flying device having the fewest moving parts, whats the slowest cruise speed achievable using a ramjet, no matter the scale of this device. Working altitude is troposphere. ...
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3answers
973 views

Is torque produced at the crank of an engine lower than at the wheels?

Im specifically referring to motorcycle engines, but for arguments sake a car engine wouldn't matter either Say 100Nm was measured at the wheel using a rolling dyno, then based on the reduction ...
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1answer
139 views

Why aren't modern pistons circular?

I'm trying to make most of an engine from scratch (cylinder, crank case, piston). I've been reading about pistons and I've learned that many modern pistons are cam ground--slightly elliptical in shape ...
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5answers
612 views

Can an electric motor use reciprocating pistons like an internal combustion engine does?

Would it be possible to have an electric motor that uses an electromagnet to force a piston up and down to turn a shaft, similarly to an internal combustion engine, but without burning fuel? Is there ...
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1answer
82 views

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 ...
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1answer
348 views

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 ...
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1answer
474 views

Effects of center of gravity very close to rear wheels of a car [closed]

I see some track race cars, especially old ones made in the 1960s-70s, are designed with the heavy components of the car sitting between the rear wheels. In fact, some of old rear-/mid-engine cars use ...
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1answer
241 views

Timing belt transmission with lateral pulley movement

What is the correct way to allow for lateral movement of a timing pulley in a transmission system? For example, there are four pulleys, one of which has to move up and down. Is there standard ...
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2answers
5k views

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?
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1answer
77 views

Torque in different car gears?

Recently I have been researching torque and horsepower. I know that the lower the car gear, the more the torque. However, whenever I see specifications of a car, it says : X lb-ft of torque at Y ...
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1answer
1k views

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 ...
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2answers
2k views

Why does a radial engine need a master rod?

Why does a radial engine need a master rod? Why can't slave rods be the only rods? Would this spider bearing (around 1:05 in the video) work for an IC engine, why or why not?
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1answer
69 views

Calculate pneumatic cylinder dimensions from work done

I have a project for which I need a pneumatic cylinder to impart an impact force in such a way that work-done/energy is 4.5 Joules, and the input pressure is 10 bar. How can I solve this so that I ...
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2answers
1k views

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? ...
6
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2answers
1k views

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 ...
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0answers
470 views

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: ...
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2answers
294 views

Methods for determining Work of Diesel Engine's Isentropic Process

Air in the cylinder of a Diesel Engine is at $30^o\ $$C$ and $138\text{ kPa}$ in compression. If it is further compressed to 1/18th of its original volume. Which of the following most nearly equals ...
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2answers
612 views

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) ...