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 carburettor engines.
Most diesel engines have been direct injection for many decades now, due to the behaviour of the fuel.
Well they both work on compression, diesels simply rely on it more than gasoline engines.
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.
yep the original diesel engine was designed to run on coal dust, unlike the modern light fuel oil diesels (kerosene, jet-A, home heating oil, and diesel fuel are all very close to the same thing, differing mainly in additives).
I just took a close look at it, and I think you're right. It's not the easiest thing to see due to the wireframe, but with a second look it does appear that the injectors are just behind the valve.
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!
For me it was when they kept changing the rules (in 2005) just to ensure that Schumacher lost. Haven't looked back since. I hear they can't even refuel these days (the horror!)
V6 turbo with energy recovery on the turbo itself. They're also allowed to use that energy to re-spool the turbo to eliminate lag. They've also hugely bumped the KERS and built it in to the throttle map - no more button for it.
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.
I'm currently rebuilding a 2.0 TDCI engine .. an interesting feature is the crowns of the pistons. With direct injection the fuel is aimed at specifically shaped depressions in the piston crowns which causes vortices between the atomised fuel and air improving the mix for a cleaner burn.
Which is actually very accurate. Modern injectors are positioned to spray fuel on the back of the valve. This helps cool the valve which protects them from heat-related damage, and also helps vaporize the fuel.
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, 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"
There are true common-rail direct cylinder injection gasoline engines out there. They're not so common though, since there aren't as many advantages to it compared to a diesel engine.
Cars marketed as GDI, such as the Ford EcoBoost, inject directly in the cylinder.
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).
Ah, carburetors - how I hated those things. Simple in theory, yet so complicated and fickle in practice...
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...
I drive a 30 year old Mercedes diesel as my primary car and it still runs like a swiss watch. You do have to adjust the valve clearance every so often, which is not necessary in a modern diesel or even ones slightly newer than mine.
I drive a seven year old motorcycle and carburetors + ethanol = nightmare. A tank of gas with the ethanol admixture will often go bad enough to gum up the carbs in just a few weeks. I've had the engine stall out under me in potentially dangerous situations twice because of this. Damn corn farmer lobby.
How a gasoline car engine works, specifically a piston car engine with injection. There are lots of other variations on the theme of car engine. For instance, Diesel, Natural Gas, LPG, electricity (non-hybrid) and another configurations for the hot chamber, for instance a Wankel engine. Instead of injection there is carburation (an older, less efficient process for getting the fuel air mixture into the cylinders), and then there are turbo variations.
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.
Indeed. It also assumes an overhead cam configuration, and ignores the possibility of a pushrod / lifter based cam/valve system. And showing a distributor glosses over the electronic timing systems that newer cars use, whereby they don't need a traditional distributor at all, just a crankshaft position sensor.
Still, for an engine neophyte, that was a pretty decent explanation.
If you find this sort of thing interesting, it might be fun to mess around with designing your own engine in Automation[1]. I've always been interested in cars, but playing around in this (currently in-development) simulation/game gave me a bunch of new insight into various engine parameters.
Now here's a good website with nice animated illustrations. But it's all one giant animated GIF. It won't scale up or down and it's already running short on colors. This is something where WebGL would excel, you could get the full color palette and make it interactive. So far all WebGL demos I have seen are tech demos or simple games that look like OpenGL games did in 2004, and they have not been really used inside websites, only as a separate square.
Yes, SVG would work too but it is not ideal for 3d. The ability to rotate the view and zoom in to see the details would make this infographic even better.
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.
Another benefit of not using a monolithic gif is the ability to translate the page to different languages. I could see a huge interest in non-English speaking countries for this.
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.
There are two measurements that can be made; RON (Research Octane Number, measuring fuel behavior at 600rpm) and MON (Motor Octane Number, measuring fuel behavior at 900rpm).
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.
My car asks for 91 octane fuel. I have no idea where I'm supposed to get that when all I see is 87, 89, and 93. Since it's an Italian-designed car, I was expecting that 91 is a common European designation. Perhaps not?
It's generally an 'at least', you probably don't need to worry about 93.
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).
Yeah, I put in 93 once and had a small but noticeable increase in power. From my understanding, this only really happens if your knock sensor is retarding your timing with 87 octane and 93 lets it advance the timing further. It's 87 minimum, 91 recommended with my engine.
Since I secretly wish my car was a small diesel, the slight lack of power with 87 doesn't bother me too much :)
Now that the price difference between 87 and 93 is typically under 10%, using 93 may actually improve your gas mileage enough to make up for the difference in price. If your drive enough that fuel expenses are meaningful, it may be worth testing if this is the case for your car.
Another note I've learned on higher octane gas: in areas prone to freezing temperatures (I live in the northern Midwest), 87 octane will, during winter, have ethanol added into the mix as an anti-freeze. This is commonly called the "winter blend", and is federally regulated to only be on the market during certain times. The ethanol has lower energy density than gasoline, and can hurt your mileage. Higher octane gas does not have extra ethanol added in. So there's a benefit to using midgrade or premium in cold weather.
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... ;-)
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.
Octane is the US is the average of MON and RON as stated in the other reply, which usually places it about 5 point below the RON number which is used in Europe and many other places. Also, in higher altitudes you don't need as high an octane, so where I live (4000ft-9000ft) premium is 91.
Nowadays hybrids are smarter. Combustion engine is used to charge batteries and provide power to the electric motor, it's more efficient way of using energy from gasoline. Using combustion with electric motor stands out to be much less efficient.
AFAIK we're still not doing it right. The best way is to make the electric motor the main motor, and having the gasoline engine be small and tuned to run at a consistent peak efficiency RPM, and only used to charge the batteries. This was figured out in 1979! http://www.motherearthnews.com/green-transportation/electric... (see the diagram in the fourth image).
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.
It's not about what engine size do you have, it's all about engine efficiency and how you drive. Small car can be efficient without any fancy hybrid technologies, big engine can be efficient with smart engineering.
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) the customer got, and so on.
^ - this. Volt fires up gas motor to optimum efficiency point to serve as a generator for the electric motor, which is the only motor connected to the drivetrain
Also, I was under the impression that coolant does not boil at that high a temperature at standard pressure. The point of the sealed coolant system is to increase the pressure and hence the boiling point, but if it boiled at that temperature by default that would be unnecessary since no engine runs that hot.
Never underestimate the pedantry of a crowd of IT-types. I used to be like that, but I grew out of it.
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 agree. People need to realise the market that this guy was targeting - it is average Joe on the streets, not the HN nerdy types. I know a fair amount engines and how they work, I still think it's very informative. The guy is a self taught graphic designer that judging by his portfolio works mainly with Photoshop. Instead of some people complaining about "it should be tech X or tech Y", maybe reach out to the guy and try to work with him.
I'd like to see one on airplane and jet engines next :)
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.
This is pretty cool. When I was younger I built a mini engine (from a kit[1], I wasn't fabbing components) which gave me a nice intro to the basics of how a car engine operates, but whilst parts of it are pretty simple to get it's helpful to see the process.
Even if it's a monolithic gif that annoys web developers. Or if it only shows one kind of engine design.
I had that same engine you link to as a kid except mine was orange instead of blue. It's definitely one of my more memorable childhood toys and even though a fairly basic representation of an engine, I agree that it was a great intro. On a side note, I remember the screwdriver that kit came with was ridiculously bad. It made stripping the included screws really easy and made putting together the model more of a chore than it should've been.
Hi fellow gear-heads... very cool engine graphics!
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.
The new Corvette does something interesting - there's a sensor on the manual gear shift lever that predicts what gear you're going to select, and will do the rev matching for you. Result is a perfect downshift, every time.
Yep, Nissan's 370Z has had SynchroRevMatch as part of its Sport/NISMO packages for a few years now, and from what I've heard through friends it's very simple and works really well... Although it makes me wonder at what point on the spectrum does a "manual" become an "automatic"
Sometimes I do not have the right shoes on to rev match so I can see this feature being useful. I would consider a car a manual if the user has to press a clutch in before changing gears.
Eh, you can revmatch without heel-toeing. I did it for years before I started driving at the track and learned how to heel-toe. You just brake enough for the turn, then let off the brake entirely and blip the throttle and drop the clutch while turning.
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.
> a dual clutch is not much faster than a properly-operated manually-clutched gearbox
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.
You seem to have ignored my "All other things the same" qualifier - that means you have to assume that power, weight (except for the difference between the gearboxes,) suspension, environment, tires, and everything else, is identical for the quoted part of my sentence to apply.
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.'
> I don't see how your first two points are relevant to what I said
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)
> with a sound system, air conditioning and creature comforts
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 suspect that a big limitation in shift speed is often the angular mass of the crankshaft and flywheel - that energy has to go somewhere in an upshift, and doing that quickly on a typical car with wide gearing and a heavy flywheel puts an incredible amount of stress on things. Gear ratios cancel out in the real world, since with close ratios you're also shifting more often.
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.
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.
>All other things the same, a dual clutch is not much faster than a properly-operated manually-clutched gearbox
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.
I'm a little surprised. I figure most people buying a Cayman S are buying it for fun. I've never driven with a DCT, but most people who have that I've heard from generally say that manual is more fun, while DCT is better in every other respect.
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.
The cayman/s has very high limits that you wont reach on a public road. If you are driving it solely on public roads, the PDK is actually great. Its good in stop and go traffic, making that occasional/daily commute to the office much more pleasant.
People buy Porsches for fun or track duty. Some for both, in which I'm in the latter crowd. I autocross my cars, and do DEs -- my current MX-5 has been on at least 13 different race courses in the country, including some of the very best (Watkins Glen, Mid-Ohio, Road Atlanta, Road America, Infineon, Laguna Seca, Sebring, VIR, Lime Rock). It's also my daily when I need to use a car to commute.
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.
Thanks for the reply :) Hope it's a blast. The Cayman S is my #1 dream car. (I currently drive a Z4 3.0si coupe and take it up to Brainerd International once or twice a year.)
My parents' car has something like this (DSG). It takes forever between pressing the gas and actually moving forward. After that the car is fast and has power, it's just not fast to get going when you press the gas, you gotta anticipate. It's really very annoying and I much prefer a normal car, I really can't recommend it to anyone, but maybe it just takes getting used to.
One day, when the sun is shining and the birds are happily chirping away in the trees, someone is going to submit a similar headline. "How X works", with X being something interesting. "How slowing down your metabolism with paint thinner works" or something.
I'll click on the article link, like I usually do and one day the article will be just one sentence.
I had a rather vague idea of these processes so it was great to see everything laid out simply.
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.
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[ 0.16 ms ] story [ 236 ms ] threadUntil 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.
(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.
https://en.wikipedia.org/wiki/Fire_piston
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.
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.
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...
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.
http://en.wikipedia.org/wiki/Twincharger
The analogical continuity of their surfaces and the discrete states of engines is very inspiring.
http://www.youtube.com/watch?v=gfr3_AwuO9Y
The whole show is well worth the time.
[1] http://www.automationgame.com
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.
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
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.
http://www.carbibles.com/fuel_engine_bible.html
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
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.
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...
http://gm-volt.com/2010/10/11/motor-trend-explains-the-volts...
Maybe later models altered that arrangement.
Nice job still.
Few people live exactly under 1 atm for any length of time.
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.
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.
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.
If the air to fuel ratio is 10, then the oxygen to fuel ratio is only 2.
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.
[1] https://en.wikipedia.org/wiki/Dual-clutch_transmission
[2] https://www.youtube.com/watch?v=C7Zh-nQPh_8&t=33
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.
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 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 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.
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.
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.
I'll click on the article link, like I usually do and one day the article will be just one sentence.
"Well"
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.
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"..