How a Car Engine Works
jacoboneal.com
jacoboneal.com
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 carburettor engines.
Most diesel engines have been direct injection for many decades now, due to the behaviour of the fuel.
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, operate like this picture, though I am sure that is not what the author had in mind.
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"
Cars marketed as GDI, such as the Ford EcoBoost, inject directly in the cylinder.
So yes, it's multi-point injection, rather than direct injection which is the new hotness for gasoline. Formula 1 will allow it from next year with the new V6 formula!
I can't remember the exact figures, but it means that they have so much torque when they go full throttle it'll spin the wheels at almost any speed.
I'm looking forward to them slipping around the corners again. Also to engines blowing up, since that doesn't happen much due to 5 year old engine designs.
(Also Diesel is the engine type not the fuel http://en.wikipedia.org/wiki/Diesel_engine)
Diesel engines work on what's called adiabatic compression heating. In other words, the compression causes the air to heat to a point higher than the ignition point of the fuel. Diesel engines usually use glow plugs to compensate for the lack of adiabatic compression heating when the engine is cold.
I do love old diesel engines with mechanical belt-driven high pressure pumps and mechanical injectors - those things were easy to fix and built to last...
On a related note, I wanted to add that, if you are not familiar with dual-clutch transmissions [1], they are pretty interesting.
One example (many manufacturers offer this type of transmission) is the Porsche Doppelkupplungsgetriebe (or simply PDK) [2], developed by Porsche. It is essentially two gearboxes in one complete transmission package, where both gearboxes possess their own clutch. When a gear is selected in one gearbox, the next gear is pre-selected in the other gearbox. The result is a nearly-instantaneous gear change, with smooth power delivery.
http://en.wikipedia.org/wiki/Synchronized_down_shift_rev-mat...
I haven't driven a stick regularly since high school, don't people rev match with their ears ?
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.
Formula One drivers in the early 90s were the only ones really able to come close, with shift times between 150 and 200ms. The average person is more around 300 - 400ms when shifting aggressively. You can be faster than 300 - 400ms, but not with 100% consistency, especially on downshifts, and especially with some transmissions with odd clutch engagement points or shift levers that require more deliberate effort.
A modern DCT, like Porsche's 2nd generation PDK, has a shift time of 150ms. Porsche's 3rd generations are even faster -- the PDK-S in the new GT3 is 100ms. The version in the 918 Spyder is 50ms. All of these are perfectly rev-matched, every time.
I've driven many tremendously good manual transmissions. However, generation two PDK is good enough that after four test drives (two with a 6-speed, two with PDK + Sport Chrono) I've actually decided to order my Cayman S with PDK since it's unquestionably better. The only thing I wish is it had the "burnout/donut mode" of the 3rd gen.
Did you find DCT to be at least as fun as manual? I think I'd miss the feeling of nailing the revs perfectly on a downshift while braking for a turn on the track.
Any thoughts?
As for the Cayman S, it's a damn serious car. My load out hits 60 in 4.1-4.2s with launch control, and the 1/4 mile in around 12.6-12.7 @ 110mph (and 175mph in ~49 seconds). A set of Michelin Pilot Super Sports will get it to hold around 1.1g of lateral grip (sustained, not peak). You can't go anywhere near its limits on public roads, except in a straight line. If you want sideways fun, there's the MX-5 and BRZ/FR-S for exactly that.
In a more powerful car (trust me, 325HP is still a lot in a 2900lb car!), DCTs give you a nice quick immediate jolt from the power surging in almost immediately. It keeps a wonderful engine note (and boy does a Cayman S with sport exhaust make some noise) uninterrupted and always on boil. Once Porsche changes its PDK shift levers to those like the GT3 (pull to upshift), those who want to think they're in a racing car with a sequential box can. If I could get PDK-S in a Cayman S, I would and would mostly use the shift lever.
I find most detractors of a good DCT haven't driven a car with one. Additionally, not all manuals are great to begin with, which can be frustrating when you're trying to be quick. The MX-5 is ridiculously good for what the car cost. The Type 997 911 had a great 6-speed as well. My Lancer Evolution VIII MR had an extremely heavy clutch, and I'd say the last few BMW M cars have had a heavier clutch than I'd prefer (and dev money was mostly spent on DCTs). Corvette Z06s and Vipers (last drove a third gen/ZB) require a very deliberate use of the shift lever.
That's not correct. When the GT-R first came out I read a great article about why it was so damn quick down the 1/4 compared to super cars that are 2-6x more expensive. The reasons were:
1. Most of them dyno at around 480hp AT THE WHEELS. So it's making more power than Nissan claims.
2. It's the first car to get all the electronics (stability control, etc. etc.) good enough to actually make it faster, not just get in the way
3. The dual-clutch gearbox changes were so fast, they did a comparison of how long the GT-R is in neutral during the 1/4 compared to other supercars with regular manual gearboxes. I remember the time difference being in the .4-.8 second range. That was the #1 reason it was so fast - it spends an extra 0.5 seconds actually putting power to the road, which is obviously huge in a ~12 sec 1/4.
I would expect something like the GT-R to have much less crank/flywheel angular mass than the average car, as well as beefed up transmission components. Even so, IIRC they had to dial things back a bit because transmissions were blowing up.
DCTs get rid of the delay from matching the input and output shafts of a conventional manual. Very helpful, but not a cure-all. My car (automated manual, non-DCT) spends much more time matching the engine to the input shaft than the input to the output shaft.
I don't see how your first two points are relevant to what I said, or your original post. You can love the GTR all you want, I don't mind, and I never claimed that there was anything wrong with it.
As for point 3, if you were to compare to a theoretical manual transmission GTR, that half a second of extra power would still only net you a couple tenths advantage, since acceleration and aerodynamic drag are nonlinear.
And I stand by my claim that a couple tenths on a 12 second quarter mile is 'not much faster.'
They're not, I just wanted to include them for the curious.
> You can love the GTR all you want, I don't mind, and I never claimed that there was anything wrong with it.
It's an amazing car, but it's not like I have one or even want one.
>As for point 3, if you were to compare to a theoretical manual transmission GTR, that half a second of extra power would still only net you a couple tenths advantage, since acceleration and aerodynamic drag are nonlinear. And I stand by my claim that a couple tenths on a 12 second quarter mile is 'not much faster.'
You've never tried to build a 12 second car have you? A couple of tens is HUGE for a well behaved road car with a sound system, air conditioning and creature comforts. You could easily spend tens of thousands on a drag car in an attempt to get that. (I just looked it up, Motor Trend ran an 11.6, which is F-A-S-T)
Reminds me of that episode with May saying something on the lines of "We're going at 400kmph... and we've got air-conditioning and radio". Now, that is serious engineering.
I had a 2006 (I think) VW GLI with a DSG and it was very snappy off the line. It was actually one of my favorite cars ever.
“Any sufficiently advanced technology is indistinguishable
from magic.” "Any technology which is distinguishable from magic is insufficiently advanced."
s/First Law/Third Law/
Obviously the quote I posted is the corollary to the quote negativity posted. Derp derp derp.
Take the above example - we really don't know how it works. We measure the amount of dopamine/serotonin in the spine before and after you take it so we assume it increases the presence of those chemicals in the brain, but it's not really mapped out.
A lot of people have the misconception that we understand the body the way we understand other technologies. That you can balance a chemical equation and deduce how something will effect the body.
While we understand a lot, this really isn't the case. And for all practical purposes it sometimes is treated like "magic".
You know what they call alternative medicine that works?
Medicine.
(cf: Tim Minchin, 'Storm' http://www.youtube.com/watch?v=HhGuXCuDb1U)
One reason is that it takes a lot of modeling to understand why to dose 1x twice a week vs 2x once a week, so everyone gets roughly the same dose.
He had a very clever argument, but the factor he was missing was radioactive decay, which provides an additional heat source. He also carefully figured that the Sun couldn't be more than 20 million years old, but here he was missing the existence of fusion as a power source.
http://www.youtube.com/watch?v=gfr3_AwuO9Y
The whole show is well worth the time.
Everything posted here is viewed as an opportunity for critique. It's driving me away as well. Perfect is truly the enemy of the good.
Truth be told, it was a few diagrams similar to these (though non-moving) that I saw and studied when I was probably about ten years old that fired up my interest in the mechanics of automobiles specifically. That turned into a long-term pursuit and I even spent several years working professionally as a mechanic and delving into some custom and high-performance work. It was doing engine performance management and working with ECUs that I dove into electrical signalling and decided to shift gears a little and get into the high-tech world, so I put myself through college at night. I still think of those diagrams from time to time.
Someone's creation of a few diagrams like this years ago opened up this kid's mind in a lasting way. I'm sure there were plenty of criticisms to be made on them, but they still had an important and lasting impact.
The main problem seems to be that it's either a simplification - which is needed because the real thing is too complex to absorb at once - or the technology choice doesn't meet their expectations.
As someone who knows all about engines, I think it's neat. Too many people don't have the faintest idea about how their car works. Though I guess most don't care and it's my desire to know how everything works that makes me odd.
I'd like to see one on airplane and jet engines next :)
every car forum / mailing list / meetup ever is full of this kind of one-upmanship.
As a Subaru driver, I was trying to picture how the cylinders in a flat/boxer engine are attached to the crankshaft: http://en.wikipedia.org/wiki/Flat_engine has a simple animation that shows it if anyone else is interested.
Of course gasoline, piston car engines are extremely common but the number of diesels can be very large depending on where you are (for instance, in Europe they are very common).
So for the general North-American view of what a car engine is this infographic is mostly correct but please don't take it as the be-all end-all of car engines, there is a lot more to it than that.
Still, for an engine neophyte, that was a pretty decent explanation.
The analogical continuity of their surfaces and the discrete states of engines is very inspiring.
Even if it's a monolithic gif that annoys web developers. Or if it only shows one kind of engine design.
[1] http://www.scientificsonline.com/smithsonian-gas-engine-mode... is pretty close, but mine was a bit more basic. 15 years seems to have improved science kits a bit.
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.
Nice job still.
Few people live exactly under 1 atm for any length of time.
I wish the 3d models that were used to draw this would be shared so I could try animating them in 3d.
And don't get me wrong, I think that this was an excellent inforgraphic.
...aside from obvious commentary of my abilities driving manual ;)
With a manual all there is between the engine is the clutch and the transmission. When the clutch is engaged your engine to your wheels is a single straight line (with some gears in between, but lets ignore those for now). If your engine has a lot of power it will simply turn the wheels, however in most cases the engine is just simply not strong enough to break the friction of the tires agains the ground, especially in lower RPM's.
When you slowly let the clutch up, what you are doing is having the engine turn faster than the pipe connected to the wheels, by using some friction material you transfer SOME of the power from the engine to the pipe connected to the wheels, as you continue rolling eventually the pipe connected to the wheels catches up and spins at the same speed as the engine (once again, ignore gearing), at that point you can let the clutch up entirely (thereby basically connecting it directly).
When you go from first to second, you use RPM matching to have the engine spin at the same speed as the pipe on the other end. When the RPM's match, you let the clutch up and from there you can start providing more power by pushing the gas pedal.
See more about clutch construction here: http://en.wikipedia.org/wiki/Clutch
---
In most automatics there is a device called a torque converter that takes care of the friction part of the clutch for you. Interestingly enough it does this using fluid rather than friction material. There are fins on both sides of the torque converter, the two sides can freely spin. One side is connected to the engine, the other side is connected to the gear box. As you press the gas pedal, one side forces fluid through a series of fins, this whips the fluid into motion, this fluid is then forced through another series of fins on the other half. Because of the pressure difference in the fluid it will eventually have enough power to start forcing the other side (attached to the gear box and the wheels) to start moving. At some point the engine side is spinning just as fast as the wheel side, at that point most torque converters will actually lock. Now the torque convertor is directly connecting the engine to the transmission to the wheels.
When it switches gears, it disengages the torque converter lock, lowers the engine RPM's (even if you keep pressing the gas, it will use the computer to inject less gas temporarily), switch gears in the gear box, let the torque converter do it's thing, and once RPM's match closely re-engage the torque convertor lock.
It's not easy, only if use it wrong. It's easy to stall going from neutral to 1st if you don't apply enough gas (for instance, if you're on a slope, or the car is loaded), but it will only stall from 1st to 2nd if you're trying to do it from too low RPM (in this case the engine may take a while to stall completely, you can still avoid it by unclutching), or if you work the clutch too fast (the engine stalls right away).
Di Pietro http://www.youtube.com/watch?v=ZGiviT-C_oY
Rotary(wankel) http://www.youtube.com/watch?v=6BCgl2uumlI
Fibonacci Offset Rotary http://www.youtube.com/watch?v=tklMGxqRtw4
k-jetronic fuel system: http://www.youtube.com/watch?v=a4fJAfXYxWk
For engines though, the "Suck, Squash, Bang, Blow" mantra used in the Secret Life of Machines was perhaps the most durable for my kids.
MON is typically 8-10 points lower than the RON.
In the US/Canada and some other parts of the Americas, they use the average of the two. Hence lower.
In most other places, they just use the RON.
http://en.wikipedia.org/wiki/Octane_rating#Measurement_metho...
If it is modern and fuel injected, 89 or 87 will probably also be fine, it just won't perform quite as well (but the computer will notice and back off of the timing).
Since I secretly wish my car was a small diesel, the slight lack of power with 87 doesn't bother me too much :)
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... ;-)
The maximum possible compression is, yes, since it is determined by the size of the cylinders and the piston stroke.
But retarding the timing amounts to reducing the effective compression--basically you are wasting some of the compression that's available by delaying the spark until the cylinder has started expanding again. I should have made it clear that it was effective compression that I was talking about.
This is a fun video about ignition order: http://youtu.be/MwEbwKBic6w (though it's more complicated since there are both 180 and 360 degree-firing V4s).
http://en.wikipedia.org/wiki/Category:Piston_engine_configur...
http://www.caranddriver.com/features/the-physics-of-engine-c...
Another fun subject is harmonic vibration and balance. Certain configurations require things like balance shafts and harmonic balancers (arguably unnecessary fluff) to offset the intense vibration, and modifying your engine can result in it self-destructing if this isn't taken into account. Inline and flat 6's and 12's are the best balanced, though the inline is more efficient and requires less maintenance than the flat.
http://en.wikipedia.org/wiki/V6_engine#Balance_and_smoothnes...
Just put 500 break-in-miles on a recent VW Boxer "Shortblock" Rebuild I did this summer!
This one is an early Bosch Fuel Injection(DigiFant), almost like sensor-assisted carburetor.. it's funky. Totally "hackable"..
though i'm not technical by any means, i've always sort of got the high-level around how reciprocating/piston-based engines function. wankel engines seem a lot more efficient in terms of design but also weirdly complex. still kind of a mystery to me as to how they work and unfortunately there aren't too many cars around these days that run on em to check out..
"Engines get hot - the cooling system of a car going down the freeway dissipates enough heat to keep two average-sized homes warm!"
Think about that for a while. ICE's just have a thermal efficiency of about 30%, the rest becomes heat.
If the air to fuel ratio is 10, then the oxygen to fuel ratio is only 2.
http://www.fiskerautomotive.com/ https://en.wikipedia.org/wiki/Yo-Mobile
Btw Yo-Mobile is interesting since they are using rotary engine to do power generation.
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) the customer got, and so on.
http://gm-volt.com/2010/10/11/motor-trend-explains-the-volts...
Maybe later models altered that arrangement.
This is a common misconception. The Volt will drive the wheels directly from the gasoline engine when driving at high speed (>70 mph).
http://blogs.cars.com/kickingtires/2010/10/the-great-chevy-v...
I also remember seeing a few Mazda rotary pickups in my early years in the US - very cool but apparently not very reliable and very inefficient.
Even steam engines.
So, yes, they're cool machines, but probably not a whole lot of utility in this context as they work the same way, but in a funky shape :)
The trouble is the damn heavy and slow to charge batteries plus of course the environmental efects of mining all the battery materials.
What we need is a fuel cell based car with electric drive.
Rotary :D
I'll click on the article link, like I usually do and one day the article will be just one sentence.
"Well"