# Tag Info

15

It depends on the car. If it's a big displacement high performance engine, then you may not be able to get the rear wheels to turn unless you're in the highest gear. If it's got an itty bitty engine, then push-starting in 1st may work best. While I don't have personal experience, because weight transfers to the front on deceleration a front wheel drive ...

14

Have you looked at the size of one of those maritime diesel engines? They are larger than your car and need to deliver a lot of power to move and power the ship. That takes a lot of fuel so it's cheaper to burn more cheaper fuel even if it is of inferior quality. The bigger size also lets it use wider fuel lines so the viscosity is less of an issue. You also ...

8

Each cylinder produces a power stroke for every (2-stroke engine) or every other (4-stroke engine) rotation of the crankshaft. A 3-cylinder, 4-stroke engine will produce 3 power strokes for every 2 rotations (720°), or one for every 720°/3 = 240° of rotation.

8

The primary issue (ignoring secondary issues like internal wear) is whether or not the engine can get rid of the waste heat. Assuming that all engines for a given fuel have roughly the same overall thermal efficiency, for a given power output, a certain amount of waste heat needs to be dissipated regardless of the physical size of the engine. The heat is ...

7

A higher gear ratio means that less force is needed to turn over the engine by pushing the car. Aside from the issue of the tires slipping, humans are more likely to be able to maintain the speed of the car long enough to allow the engine to start if it is in a higher gear. If you are tow-starting the car, the same thing applies: in a higher gear, there is ...

7

They are very nearly equal for typical four-stroke non-turbo diesels under load. A turbo diesel under load should have slightly more radiator loss than exhaust loss. At the bottom is a link to the technical spec sheet for a Cat 3412 powered genset. It's a probably a bit bigger than what you had in mind. It is a turbo with aftercooler (A/C in the doc below). ...

7

Yes - for certain applications. Low-energy, low-temperature, small installations, possibly 'accessory' power where providing a bit of weak rotary power to some point of machinery would be difficult but a good heat gradient is at hand and can be utilized - generally things where you have a heat source above your alcohol boiling point but not providing nearly ...

5

Simple economics. Marine engines consume enormous amounts of fuel, so in order to reduce operating costs, they use the cheapest, least desirable sludge that the oil refineries can produce.

5

From the Wikipedia article: All diesel engines can be considered to be lean-burning with respect to the total volume, however the fuel and air is not well mixed before the combustion. Most of the combustion occurs in rich zones around small droplets of fuel. Locally rich combustion like this is a source of NOx and particles.

5

Most (modern) small and large car engines are designed for 100% duty cycle. This means that at 100% rated power(gas pedal all the way down) the engine can run continuously. Heat dissipation is the limiting factor like Dave Tweed stated. Cars that are not designed to continuously dissipate 100% of the heat generated at max power require the driver to watch ...

5

A diesel engine for a car needs a fuel which is liquid even in winter. This fuel should contain a very small amount of sulfur to limit air pollution. The marine bunker oil is not liquid at room temperature, it has to be heated to about 50 °C before pumping out of the tank and to about 130 to 140 °C before injecting it into the cylinders. It contains a lot ...

5

A stroke consists of either one expansion, or one contraction. As such it corresponds to half of a rotation of the shaft. In a three cylinder engine, each cylinder will stroke with 2 strokes per revolution, so that's 6 strokes per revolution. However, in a four stroke engine, it takes four strokes for each cylinder to complete one cycle, and only one of ...

5

Brakes are used. And tyre wedges are also used. Turbo prop has the blades feathered to not produce any thrust. A jet is producing enough mass flow to run and little thrust.

4

That's because when you upshift, you select a lower ratio, so your clutch speed drops. Since you took your foot of the gas, the engine rpm also dropped, and now the clutch and engine speed are close to synced, and hence little force is felt when you engage the clutch. The best way to upshift is to relieve the throttle a little(not fully), so the rpm will ...

4

There is no reason in principle why a custom engine builder couldn't cast a block themselves. Everything done by the level of automation in this process could by done by hand, given enough highly skilled craftsmen. https://www.youtube.com/watch?v=5oUDzkkdkpQ Whether there are customers who would want to pay for a hand-made block which costs as much as the ...

3

Gaskets are selected based upon the mating surface materials, pressure, surface area, surface condition and what they are sealing. As far as I know, harder gaskets are used in harsher locations. But there are many factors involved with modern to do with making them lighter and stronger. A strong steel gasket may be applied to a cylinder head because it adds ...

3

The crosshead bearing slides within a track and connects to the conrod and then to the crankshaft. In a vertically oriented engine the pressure on the bearing is always downwards, resulting in a depleted lubrication film on the lower contact surfaces of the bearing shell. To supply lubricant to the entire bearing, high pressure oil is injected into the ...

3

One possible reason for placing the engine and most of the weight at the back of the car would be to improve rear wheel tire friction. This would be useful if the car has a rear-wheel drive, since the car's ability to accelerate is limited by the amount of torque the wheels can support before slipping. Adding weight to the back of the car would increase ...

3

"Let me say this about that" (extra points to those who recognize the originator of that phrase). First: yeah, they've invented a cool-looking device. But, they appear to be getting nowhere so far as either advanced funding or a fieldable model produced. Second: I have seen at least 5 or 6 "groundbreaking new powerful/efficient/wunderdevice" internal ...

3

The answer depends on factors like the bypass ratio of the engine and the design of the thrust reverser, e.g. bucket doors at the back of the engine or vanes to deflect the bypass airflow from the fan. By the OP's proposed measurement (reverse thrust / forward thrust), the efficiency is also strongly dependent on the engine speed. At maximum thrust the ...

3

I never heard of pushing a car is 1st; have you tried it ? In the good old days when cars were not so reliable , I started more than a few in 3 rd ( of 3 speed ). Occasionally started one in second by letting out the clutch after it was moving then quickly pushing the clutch back in and hoping it started instead of sliding the wheels. Maybe with a small ...

3

Having pushed many cars on many occasions, on snow as well as gravel and tarmacadam. I can categorically state; on gravel 3rd best nothing lower than 2nd, on snow 4th you can try 3rd and you may be lucky, that's if you have chains or studs on, on Tarmacadam 2nd gear, no lower. Downhill you could use 1st but I would still recommend 2nd. The reason is ...

3

For every action there is an equal, but opposite, reaction. Never found a case that this is not true. Torque reaction on the P51 even caused uneven tire wear: https://www.aopa.org/news-and-media/all-news/2007/august/pilot/north-american-aviation-p-51d-mustang So, if you open the bonnet or hood of a car and run the engine with it in neutral, then blip the ...

2

OK, fair warning: I am answering my own question and am not a engines person. So this could be wrong. The real limit in the engine is how hot certain parts can get without breaking. This temperature is related to the gas temperature after combustion via the cooling system and the cylinder design (convective heat transfer between the gas and the cylinder ...

2

Your second attempt is correct, you just had two mistakes: If you re-calculated $V_1$ you'll find that it equals $0.01503$ not $0.0158$ $m^3$. same issue with $P_2$. $$P_2 = \frac{138*10^{3}*0.01503^{1.4}}{(8.3529411*10^{-4})^{1.4}}= 7.889*10^6\ Pa$$ Substituting in isentropic work equation: $$W = \frac{P_2V_2 - P_1V_1}{k-1} = \frac{(7.867*10^6 * 8.... 2 Having a master rod means that the bottom bearings of the connecting rods follow a fixed path throughout the cycle. If they are all attached to the crankshaft via a spider bearing it the spider bearing itself has an extra degree of freedom to rotate around the crank bearing, having a master rod constraints this rotation. Because the con rod bottom ... 2 It is possible to calculate this under the assumption that all of the energy from the expansion goes into mechanical energy instead of being lost to heat transfer through the walls. In this case the process is called adiabatic, and the work done is given by$$ W = P_0V_0^\gamma\frac{V_f^{1-\gamma}-V_0^{1-\gamma}}{1-\gamma}, $$where$$ \gamma=\frac{C_p}{...

2

The torque indicated by the car manufacturer is usually measured at the engine's output, without use of the gearbox. However it is still a good indicator of the car's global performance, but only if you pay attention to which rpm provides the higher torque. Example : 100 Nm @3000 rpm is a better performance than 100 Nm @7000 rpm since the first one is ...

2

One important reason is that diesel fuel had a high molecular weight compared to gasoline this means that is is more difficult to disperse as it forms liquid droplets as opposed to vapour and even more importantly there are many more intermediate reactions involved in complete combustion. For example Hydrogen, H2 burns very easily in oxygen as combustion ...

2

Theoretically Ramjet should start working from 0.5 Mach (this is the speed where compressibility of fluids becomes significant). But it won't be much efficient until ramjet reaches around Mach 3. Because RamJet compresses incoming air by slowing down the air speed. More the speed of incoming air more compression can be achieved. Around Mack 3, diffuser can ...

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