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How a Car Engine Works

jacoboneal.com

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Re: How a Car Engine Works

#121

Post by jpindar »

sitharus wrote: post #4

It's worth noting that the engine illustrated is a gasoline direct injection engine, which are fairly common on new cars but historically not so. Until the early 2000s most fuel injected gasoline engines were multi-point injection - the fuel was injected in to the incoming air stream immediately before the cylinder, and before that indirect injection which injected where the carburettor was. Then there are carburetto…

Also note that it has a distributor, which is uncommon on new cars. New cars generally have one coil for each cylinder (or pair of cylinders that fire 360 degrees apart).

Re: How a Car Engine Works

#122

Post by njoubert »

jcampbell1 wrote: post #54
sitharus wrote: post #4

It's worth noting that the engine illustrated is a gasoline direct injection engine, which are fairly common on new cars but historically not so. Until the early 2000s most fuel injected gasoline engines were multi-point injection - the fuel was injected in to the incoming air stream immediately before the cylinder, and before that indirect injection which injected where the carburettor was. Then there are carburetto…

Direct injection implies the fuel is injected at the top of compression stroke, but the animation shows the fuel being added during the intake stroke. This is just an inaccurate drawing showing the injector attached to the cylinder rather than the intake manifold. Interestingly, this could be a drawing of a ultra modern gas direct injection system running in classic mode. Ford's EcoTech will, under certain conditions…

Beat me to it!

This totally amazed me when I started working on cars. Both carburetors and direct injection creates a mixture of gasoline and air BEFORE this mixture enters the cylinder. Direct injection now seems like a misnomer ;) It makes a lot of sense if you think about the incredibly violent conditions inside the cylinder head though. I'm always surprised that spark plugs survive as easily as they do, I imagine a high accuracy injector nozzle in that situation would not last as long as current injectors. Has anyone done a true direct-injection design?

Jacob, can you update the drawing slightly? "The fuel injectors spray gas into the cylinder..." is incorrect, it should be closer to "The fuel injectors spray gas into the intake manifold where it mixes with air before being sucked into the cylinder"

Re: How a Car Engine Works

#123

Post by mzs »

allworknoplay wrote: post #62

Since we've got a bunch of awesome gearheads commenting, can someone tell me why manual transmission is so easy to stall out? Particularly between say 1st and 2nd (although I'm sure it's got nothing to do with the actual gears). Just curious. ...aside from obvious commentary of my abilities driving manual ;)

I agree with the others, you might be shifting too early and so the RPM will be too low for 2nd. Did you have trouble at higher RPM to shift into 2nd, like the gear shift would not move it, so you started trying to do so sooner? If so it may be that you were trying to shift too quickly (the actual action of shifting). It's okay to push the clutch in, go into N briefly, and let the RPM drop a bit before shifting into second. So say you start the shift at 3500RPM, maybe let it drop to 2700, every car is different though. A mechanical explanation might be that your throw-out bearing is shot, but I think you would hear or feel it if it was that bad.

Re: How a Car Engine Works

#125

Post by ChuckMcM »

This is an awesome infographic. One of the most used books in our home school curriculum was "The Way Things Work" which, for the most part, covered pretty much all of the things that we needed it to. We also took apart a few things to get a more 'hands on' appreciation of the mechanics.

For engines though, the "Suck, Squash, Bang, Blow" mantra used in the Secret Life of Machines was perhaps the most durable for my kids.

Re: How a Car Engine Works

#126

Post by mzs »

kineticfocus wrote: post #13

I always found this one video ( http://youtu.be/K4JhruinbWc ) on differentials enlightening.

Those old Handy organization films are incredible, here is my favorite but GM commissioned a lot of them.

http://www.youtube.com/watch?v=CCtJlgtZnBY

The US Army also has many very nice ones intended to introduce mechanics as well, there is one about power steering that is very good, but many more as well.

http://www.youtube.com/watch?v=AlpvyWAA8a0

Re: How a Car Engine Works

#127

Post by maxerickson »

chiph wrote: post #58
maxerickson wrote: post #30

Earlier quoted context omitted.

That isn't true, most hybrids still have a mechanical connection between the combustion engine and the drive wheels. That is, the Prius, Ford hybrids, GM hybrids, I'm sure others.

AFAIK, the Chevrolet Volt (and Opel clone, etc) is the only one where the engine just charges the batteries, and the drive wheels are run by the electric motor alone. From a technical standpoint, it's a good design for a hybrid - you can optimize each part of the system separately. But GM didn't quite get the car as a whole correct -- it has some ergonomic problems, priced higher than the value (perceived and actual)…

I actually checked before my comment. This article states that the combustion engine participates above 70 mph:

http://gm-volt.com/2010/10/11/motor-trend-explains-the-volts...

Maybe later models altered that arrangement.

Re: How a Car Engine Works

#128

Post by lutorm »

pdonis wrote: post #114
freehunter wrote: post #110

Earlier quoted context omitted.

But if the engine is running on lower power because of the knock sensor, higher octane should be called for, right?

Yes, because that means the knock sensor is reducing compression because it senses lower octane gasoline.

Compression is fixed by the engine design. The only thing the ECU can do as a result of knock sensor input is retard ignition and close the throttle (and, on a turbocharged engine, lower charge pressure).

Retarded ignition does result in lowered gas mileage, but throttling down does not. It just decreases your maximum available power.

Plus, if you notice the decrease in power, your driving is not suitable for comparing gas mileage... ;-)

Re: How a Car Engine Works

#130

Post by gelstudios »

nexox wrote: post #84
grecy wrote: post #75

Earlier quoted context omitted.

That's one of the major reasons the GT-R is so quick off the line and down the quarter mile. It was the first production car with a dual-clutch transmission that was actually realistically priced, and it's still arguably the most cost-effective.

Actually VW sold a dual clutch DSG transmission in the 2003 R32, years before the GTR hit the market, and for a fraction of the price. All other things the same, a dual clutch is not much faster than a properly-operated manually-clutched gearbox, but in the case of the GTR, we'll never be able to make that comparison.

Since we're talking robo-manual transmissions, I think you guys would appreciate Koenigsegg's clever design. They use a wet clutch (as a brake) on the input shaft of their transaxle to quickly match the speed required by the next gear. End result is a lighter weight single clutch transaxle that shifts just as quickly as the DSG/PDK dual clutch designs. Let's just ignore the 1.5M price tag.
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