Motor Vehicle Maintenance & Repair Stack Exchange
Motor Vehicle Maintenance & Repair Stack Exchange

Questions tagged [engine]

Questions about vehicle engines. Most engines in road-going vehicles are 4-stroke internal-combustion gasoline or diesel engines.

There are many different types of engines.

  • Most engines in road vehicles are four-stroke or internal-combustion piston engines.
  • Some older vehicles use engines, but these aren't used anymore because they're incapable of passing modern standards.
  • An uses electric motors (typically one per wheel) rather than an internal-combustion engine.
  • A few heavy off-road vehicles use engines, which are very powerful but slow to start and stop.
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What actually happens when there is not enough oil in a car engine?

When a car is topped up with oil, it clear to most people that you are supposed to fill it to the recommended amount as specified by the manufacturer (normally on a dip stick). What exactly are all of the disadvantages to running an engine when the…
Max Goodridge
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Is it necessary to 'burn in' or 'break in' a new car?

I've just bought a new 2011 plate car. I've heard stories of people 'burning in' engines for the first few hundred or couple thousand miles using methods such as: Not driving above 50 mph. Varying the revs more than usual throughout the entire…
Alex Humphrey
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What does a water-like drip coming out of the exhaust of the car signify?

Sometimes while driving in the traffic, I come across a car or two which would be dripping water-like drops from its exhaust steadily in 4-5 second intervals. I tried to ask a couple of people at the local workshops; they say, and I quote, "The car…
Sandman
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Why are the blades of car radiator fans unevenly spaced?

Fans that look like this: Is it to somehow help the balance of the engine?
Sam
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Changing Firing Order in a 4 Cylinder Car

Backstory In motorcycling you can get cams that change the firing order and time from a traditional 1,3,4,2. It's was very common in American road racing in the 1990's to hear 4 Cylinder engines that sounded like two cylinder v-twins. The way these…
DucatiKiller
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Why do manufacturers detune engines?

I was wondering why a manufacturer would detune an engine. An example -- there are many others -- is the Mercedes-Benz OM612 engine. Same engine, lower (peak) power output in the Sprinter than in the E-class. The same hardware (and thus the same…
Ben
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Spark plug broke off in engine - can I drive the car?

I own a 2004 Volvo XC90 T6 2.9L AWD with 6 cyl. (Twin turbo, with catalytic converter.) While changing the spark plugs, one broke-off (all the ceramic below the threads and possibly the metal finger of the plug - I'm not sure) and fell through the…
VolvoXC90_T6
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what is difference between DOHC and SOHC?

I want to know the SOHC and DOHC configurations. On what factors an engine manufacturer decides to go with SOHC or with DOHC, what should I choose? DOHC or SOHC?
BraveNinja
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Why do two-stroke engine exhaust pipes look so strange?

Two stroke gasoline engine exhaust pipes are shaped strange. They expand into a wide diameter and then shrink down to a very small diameter where the exhaust gasses emerge into the environment. - Why are they shaped in such a strange way? - What is…
DucatiKiller
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Why is engine displacement frequently a few CCs below an exact number?

I've noticed that engines are rarely exactly 1.5 liters or exactly 4.0 liters, and I'm okay with that. It makes sense that engines would have some arbitrarily ideal size for specific applications, so I would expect exact engine displacement to be…
Trevor D
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5-Stroke Engines - What are these things?

What is a 5 stroke engine? Why aren't they using them in vehicles right now? Is this a new thing or has it been around for a while?
DucatiKiller
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Static vs. Effective compression: Why does higher effective compression not require higher octane gas?

Background I've been trying to do a lot of research on boost lately because I'm planning on running a moderate turbo setup on my daily/light-duty-autox car in the future. I'm trying to get into the physics of things so that when I do my build, I'm…
Annath
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We have fuel injection, why not air injection?

I'm finishing studying EFI systems, which set me thinking about induction more generally. We inject fuel from a high-pressure common rail for many good reasons. We're capable of making stratified burn within a cylinder, provided we have full control…
Daniel
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Is Start & Stop technology good or bad for my car? (Alfa MiTO)

I was recently in the lucky position to obtain an (almost brand new) Alfa Romeo MiTo, Progression. Like many new cars coming out these days, it has "Start & Stop" technology that turns the engine off when the car is stationary and is put in neutral…
DeVil
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What are the risks of overfilling a small engine with oil?

I recently overfilled a 4 stroke lawnmower engine with oil. It has been run for about 1.5 hours while overfilled. It smokes a lot right after being started but after 30 seconds or so the smoke clears. Now that I have figured out what I did I plan to…
Greg B
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