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14

There are a few important factors at play here. Hot air rises, cold air sinks In physics-speak, hot air is less dense than cold air. This means that the volume occupied by 1 kg of hot air is greater than the volume occupied by 1 kg of cold air. The internal combustion engine is a volumetric device What this implies is that every time the engine turns ...


5

It sounds like there is an issue with something in the vehicle after it goes from open loop (before sensors are used to run the car) to closed loop (where the vehicle starts using inputs from the O2s, MAF, and other sensors). This switch over usually occurs about two minutes from a cold start-up. I would start by cleaning the MAF with electronics cleaner ...


5

What is Compression Ratio: An engine's compression ratio is the ratio of the volume of gas in the cylinder when the piston is at the top of its stroke (top dead centre, or TDC) to the volume of gas when the piston's at the bottom of its stroke (bottom dead centre or BDC). In other words, it's the ratio of compressed to uncompressed gas, or how tightly the ...


5

You are mostly correct in your assumptions. However, you write: "In Diesel Engine the right amount of Diesel for the right amount of Compressed air is more important, Injecting more fuel alone will not increase the torque." This is not correct, perhaps you meant for a petrol engine? Anyway, the way a petrol engine works is by having a throttle in the air ...


5

In addition to Zaid's answer. VTEC - Variable Valve Timing and Lift Electronic Control) In essence, it selects between two different cam profiles depending on the RPM. Here's an animation - This is how a cam controls poppet valves. Read about cam profile here For volumetric efficiency we want the intake stroke to fill the cylinder with the max - ...


5

When the engine is cold, the engine does not run as well, so it counteracts this by running at higher RPM to avoid stalling. The main issue is fuel vaporization. Fuel vaporizes at 196*F. Unvaporized (liquid) fuel does not burn. To keep the engine running while cold, the ECU adds in extra fuel. On carbureted engines, they used a choke. The rich mixture ...


4

This diagram does a decent job of explaining VTEC: In a nutshell (paraphrasing the Wikipedia article), you have two cam profiles, one designed for low-RPM operation and fuel efficiency, the second (taller cam) for performance. The ECU decides when to select which profile based on several engine parameters by actuating the locking pin that runs through ...


4

What are examples of designs that mitigate the issues of driving in heavy rain? The best mitigation is not to drive in it. Most roads are designed with a crown in the road (high spot in the middle), which allows the water to run off at a fairly rapid clip. This helps eliminate standing water to an extent. During extreme rain, this isn't possible and you ...


4

The red arrow in the low resolution picture appears to point to the frame. The third picture shows the same side of the engine and a clear view of said frame.


4

Variable valve timing permits an increase in the torque in the lower engine speed ranges and increased engine power in the higher engine speed range. Basically, the system alters the relative position of the inlet camshaft with respect to the exhaust camshaft corresponding to the engine operating conditions. the idea is to control how long the "valve ...


4

Compression test is more to test if there is a problem. If your compression is low, it could be a number of different issues. You can test the rings by adding oil to the cylinder and see if the compression is higher. Other than rings it can be difficult to determine the source of the issue. A leakdown test will tell you where the problem is. By watching ...


4

A tachometer typically has 4 inputs - +12v, ground, signal and light. +12v goes to switched power, you can tap into the power for the radio or cig lighter. Ground goes to any good body ground. Light get tapped into the power for your dash lights (or headlights, fog, light signal to the radio, etc.) Signal typically goes to the negative side of the ...


4

In Short its based on low burn rate of diesel plus the longer stroke of the diesel engine. First you must understand the difference between these engines, the diesel works on purely compression of fuel , heating and generating bang to produce power, the gasoline on the other hand is natively twitchy and needs a spark to explode and produce power on its own. ...


4

There are general things which you can do and look for to examine the mechanics work. These are not fool proof, but should give you an indication of the level of work the mechanic produced: Does the exterior of the engine look clean? In order to do a good rebuild, you need to have a clean block and head. If they aren't clean, what do you think the inside ...


4

Engines are designed to withstand a certain amount of stress. When you exceed that threshold, longevity will start to deteriorate. I stated something to that effect in this answer. The engine has a redline where you shouldn't take its speed past. This redline is not the maximum speed which the engine car run, but more correctly the threshold which you ...


3

Basically the sky is the limit. If you can dream of something which it can connect to, you could utilize it. There are limits, of course. I mean, you couldn't pull out a 400lb engine and expect to put it in an RC car. If you can devise a way to mount it and attach it to an object which needs power, you can make it happen. Things which I've seen engines used ...


3

To expand on Anarach's excellent answer; the burn rate of diesel is slower than petrol and at higher RPM you would risk the exhaust valve opening whist the mixture in the cylinder was still burning. Increase the RPM higher, especially on engines designed with some overlap so that inlet and exhaust valves are open at the same time and if you still have a ...


3

i-VTEC changes HOW MUCH the intake and exhaust valves can open. VVT changes WHEN the intake and exhaust ports open. It's a lot of information to put in an answer. The short version is that by electronically changing exactly when the intake and exhaust valves open and close, you can increase the volumetric efficiency of the engine across a large RPM range. ...


3

As per my understanding, Diesel engines are quantity controlled and Gasoline engines are quality controlled. The reason being in Gasoline engine for a proper combustion, the mixture formation is very important. There should be homogeneous mixture of air and fuel for a complete combustion to happen. therefore the quality of mixture is very important. That is ...


3

A cylinder leak-down tester is a completely different animal than a combustion leak detection kit and has a completely different job. While the combustion leak detector checks for carbon-dioxide (CO₂) in the radiator. The cylinder leak-down tester kit hooks up to to your cylinder through the spark plug hole on one end and to your compressor on the other. You ...


3

A burnt valve can happen for one of many reasons, but the underlying issue is, the valve is not sealing correctly and allows hot engine gases during the combustion phase to leak past the seal which is formed by the valve and seat. When the seal is lost, the hot exhaust gases escape past the valve (can happen to either the intake or the exhaust valve, but is ...


2

In four stroke petrol engines there are four parts to the combustion cycle; Suck (draw in fuel, piston dropping down the bore) Squish (compress the drawn in fuel, piston rising up the bore) Bang (the fuel is ignited and combusts, piston forced down the bore) Blow (push burned fuel into exhaust, piston rising up the bore) Because of the reciprocal nature of ...


2

Hydroplaning, while this can happen on light rain as well, is when you loose traction with the road due to water build up on the road. When there is flooding, you want to take it slow, as the water could be deeper than you expect it to be, but also because if a current is strong enough, it could float your car up some and drag it down current with you ...


2

The battery shouldn't make a difference, providing the alternator is working properly. However, if you don't have a starting problem, that suggests it isn't the battery that is the root cause of the problem - more like something electrical. From the symptoms you describe, it sounds more like a fuelling issue - perhaps the fuel pump is cutting out after a ...


2

The Twinport Ecotech engine is the second generation of the GM Family 0 engine technology (also called Family Zero ... haha, could even be "Family Zed" in the right parts of the world, eh?). It works by having the ability to close off one of the two intake ports near the intake valve at low engine speeds, which speeds up the air entering the cylinder and ...


2

Are your mounts located directly near your exhaust manifold? Do they have a heat shield? The rubber can dry and crack due to the heat from the exhaust manifold if not properly insulated/protected from the heat. On my 944, there is a small tin heat shield that protects the mounts from the manifold. Leaking oil onto the mounts will also accelerate their wear, ...


2

Valves can bend, break and/or burn. If the valve's don't provide a complete seal, for whatever reason, the hot gases are forced past the valve which eat away or burn away the edge of the valve due to concentration of heat and pressure. Causes that I can think of - Anything that causes incorrect valve seal Cooling issues (improper cylinder head ...


2

It simply means a half burnt valve thus preventing it from sealing against its seat When there is no sufficient cooling in the engine it may cause the seal of the valves to give way(exhaust valve generally), gradually over the course of time the exhaust gases escape even without the valve being fully open thus increasing the risk of further damage. A ...


2

Your question is subjective, but I can share some of my own experience in working with Subarus. The difficulty level of working on these engines will be defined by your mechanical ability and the type of work you plan on doing. Routine maintenance is fairly easy. The engine bay is easy to get around in my opinion, but it may take some getting used to. ...


2

It sounds to me as though they didn't put (enough) oil back in after the engine flush. First of all, it didn't need an engine flush. Mobil1 and other synthetics are renowned for not leaving deposits in the engine. I would bet your engine would have been sparkling clean on the inside. They sold you something you didn't need. (I'm betting something along the ...



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