Why are almost all modern engines 2.0-litres?

the days of the v12 are nearly over the days of the v10 are nearly over the v8 is doing its best to hang on the v6 is even starting to struggle the car industry is currently in a huge period of upheaval especially in the powertrain department and the vast majority of manufacturers have opted for one of these a two liter four cylinder turbo engine the list of cars that have two liter turbos is enormous right now so why is this the engine size and layout of choice let's start with the displacement two liters split over four cylinders do some quick maths and you end up with 500 cc's of displacement per cylinder and look elsewhere in the car industry and a pretty serious trend starts to become clear let's start with the bottom three cylinder engines they're generally 1.5 1.6 liters divide 1.5 by 3 you get 500 cc per cylinder four cylinders generally two liters divide that by four 500 cc per cylinder six cylinder engines straight sixes and v6s they're generally three liters these days divide 3 liters by 6 500 cc per cylinder 4 litre v8 500 cc 5 liter v10s 500 cc 6 liter v12s 500 cc almost every modern production engine uses a 500 cc per cylinder layout so why is that the magic number well it all comes down to the shape of the combustion chamber a bunch of german university students did a whole load of experiments around a decade or so ago to find the ideal shape of a cylinder for efficient and powerful combustion and it turned out that a slightly under square engine came out on top by under square i mean that the length of the stroke of the engine is slightly longer than the size of the cylinder bore almost completely square but not quite meaning that the border stroke ratio is less than one an 86 by 86 millimeter combustion chamber achieves that 500 cc cylinder so modern engines slightly tweak that recipe to something more like 82.5 millimeters by 92.8 millimeters like in this cupra [Music] but i want to go further why is a slightly under square 500 cc cylinder seen as the optimum what did those german students actually find well i've got an appointment with the best in the business to take a deeper dive on this one but before then we've got a new sponsor supporting the channel this is for you volkswagen audi guys a great thing about all of these two liter engines is that a lot of them share componentry and they can be very tunable flexible to a bit of tinkering and that's where one of these obd-11 adapters can come in very handy first of all you can use it as a diagnostic tool to search for fault codes within your ecu you can also get it to send live data through to your phone where in the past you'd have to fit a gauge for stuff like engine oil temperature charge air pressure and throttle position you can now get all of those readings and more sent straight to your phone obd-11 is the first third-party diagnostic tool that allows real-time access to the newest models communicating directly with volkswagen servers to unlock control units you can also use it to change the configuration of your car to your liking for example if you want your car sounding at its best at all times and not have to keep touching that exhaust valve button you can plug this in hop onto the app and boom completely deactivate the exhaust valve for goods you can also change up the dynamic of your car by changing stuff like completely switching the esc off and sharpening the throttle response these are all the brands that they cater for so if you fancy one of these adapters to use in your car and to help support this channel click the link in the description below they have a whole load of pre-christmas deals on the go this thing caters to everything from a lupo to a cooper leon to a lamborghini veneno not bad let's have a chat with the big boys i have always wanted to come to cosworth the dfv the hb the yb the ca this place is a true temple to the design and manufacture of pieces of art like these [Music] bruce i couldn't think of a better man to chat to about the subject matter it's a bit ironic that we're standing in front of the 6.5 liter valkyrie engine but i'd like to chat to you about two liter engines if that's okay sure it turns out there's a bit of a rumor on the internet that german university students found out that a 500 cc slightly under square cylinder is perfect for a modern internal combustion engine why is that the case what physically about that means that that's perfect so uh yeah i hadn't heard that rumor before which is not safe but certainly you're absolutely right that that kind of internal combustion engines have honed in on that sort of 500cc per cylinder there's several very good reasons for it if you go much smaller than than than that then you end up with a high surface area to volume ratio and that's bad because because that surface area if you have your flame front getting to that um the walls of your combustion chamber then they're extinguished very very quickly it's that surface area where all the heat gets out of the cylinder into the water you don't want that heat to be heating up the water you want that heat to be pushing the piston down yeah so so if you go too small that's the problem you enter into you have too much surface area for your volume and so you end up extinguishing your flame before it's fully burnt out conversely if you go too big you have exactly the other problem that your flame front progressing across the the cylinder bore burns out before it reaches the edges so you have what's called end gas kind around the edges which is which is very difficult to burn that's how you get like liquid fuel down the crevice volumes around the top of the pistons so that comes very bad for emissions so there's no 500 isn't a magic number it's not like if you go to 499 it's not going to work yes um but you know in that kind of high 400s low 500s um works very nicely to say it's neither too big nor too small for nearly every application and then it also sort of fits very neatly with most of the kind of car companies vehicle strategies you know if your marketplace is driven by competitive pricing for the vehicle that's when you probably want a straight four obviously a single bank of cylinders where you've got one cylinder head is cheaper to produce than a v engine where you've got two cylinder heads so it fits neatly into a two liter straight four up at the other end of the market um say this end of the market um if you're looking for a thousand horsepower then it's going to be yeah you're not going to get it from a straightforward yeah but this has slightly strayed so this is a 6.5 so that's slightly more than 500 cc so is that governed by a power number that you wanted to hit or what changed this from being 6 liters yes so when we went into this program originally the target was 950 horsepower and and through the sort of development of the engine we ended up moving up to a thousand horsepower we couldn't quite get the power we wanted out of six liters we didn't particularly want to push the rev limit any further because at the time eleven one seemed enough it seemed a lot in the road car world yes so we said okay well let's squeak the capacity up a little bit and that's what i was saying earlier about 500 isn't a magic number it doesn't matter if 500 becomes 5 10 5 20 whatever so um so yeah so we put a little bit of extra on the capacity to get that target power without um having to go even further on the um well bruce thank you very much for your time there's two liter engines explained to reduce production costs and engineering complexity once that 500cc formula was found most of the manufacturers decided to adopt modular powertrains meaning that three four and six cylinder inline engines shared a lot of the same components before we knew it all the local brands to those german students mercedes bmw and volkswagen were all building 500 cc per cylinder direct injected slightly under square engines it is remarkable what engineers can do with just two liters these days pretty much the entire hot hatch game is dominated by the two liter engine apart from the grs and the rs3 but they both still operate in that 500 cc per cylinder window the two liter turbos start at about 190 200 horsepower but then the golf r came along and changed the game up to 300 horsepower through volkswagen's tsi engine which is what this thing has here this cooper leon has 300 and what makes this engine so impressive is how quickly it reaches its peak torque value it gets there at just under 2 000 rpm and then it's almost a straight flat line throughout the rest of the rev range which makes it so quick if you wanted that level of performance back in the day there would normally be a transverse v6 in the front squeezed into the engine bay but those engines would only reach their peak torque at about 4000 rpm which seems like an age compared to this thing let's try that again fourth third second it is instant when you want it and it's everywhere there's peak torque there's peak torque there's some more peak torque this car is all about what an engine and by replacing that big white transverse v6 with a nice narrow inline engine you create much more space in the cabin in the boot for model train boxes and dogs then there's mercedes amg who have taken things to a whole new level again they are flirting with 400 brake horsepower from their 2-liter 4-cylinder turbo engine that's 100 brake horsepower per cylinder or 100 horsepower per our magical 500 ccs you don't have to hop back too far to when full-blown super cars were creating that much power from 8 and 12-cylinder engines and yet we now have what can only be classed as super hatchbacks creating that much power using only four but for how much longer [Music] this era of the car landscape reminds me a bit of the late cretaceous period stick with me on this one the t-rex is the v12 the velociraptor is the v10 the v8 is the triceratops the v6 parasaurolophus and then boom the meteor of dieselgate hits into the world quickly followed by the constant volcanic eruptions of elon musk blotting out the sun and what emerges from that cataclysmic event birds the only dinosaurs to survive that extinction the small inline three and four turbocharged engines and then it moves the warm-blooded mammals the evs that will soon dominate the globe and change the environment forever there will be a day when even these prevalent two-liter engines are thing of the past like the great flightless birds the moa and the dodo we all know what happened to them they may seem a bit clinical and efficient to us now but one day we might look back and think differently [Music] [Music] you

Channel: DRIVETRIBE

Views: 1,314,723

Keywords: jeremy clarkson, richard hammond, james may, cars, top gear, the grand tour

Id: b9OnI3j5G7g

Length: 12min 54sec (774 seconds)

Published: Fri Nov 19 2021

Reddit Comments

[u/Maximilianne]

Reject modernity, return to 1.5L V12 engines

[u/Drzhivago138]

.5L per cylinder is kind of a sweet spot. 1.5L I3s, 2.0L I4s, 3.0L V6s. Although V8s are almost always bigger than 4.0L.

[u/UnderwhelmingAF]

The 2021 model year cars sold in the US that offer a 2.0L is quite extensive. Please forgive me if I forgot any….

Acura: RDX, TLX

Alfa Romeo: Giulia, Stelvio

Audi: A3, A4, A5, A6, A7, Q3, Q5, Q7

BMW: 2, 3, 4, and 5 Series; X1, X2, X3, X4

Buick: Envision

Cadillac: CT4, CT5, XT4, XT5, XT6

Chevrolet: Blazer, Camaro, Malibu

Ford: Bronco Sport, EcoSport, Edge, Escape, Transit

Genesis: G70

GMC: Acadia

Honda: Accord, Civic, CR-V

Hyundai: Elantra, Kona, Sonata, Tucson, Veloster

Infiniti: QX50

Jaguar: E-Pace

Jeep: Wrangler

Kia: Forte, Seltos, Soul, Sportage, Stinger

Lincoln: Corsair, Nautilus

Mazda: 3, CX-3

Mercedes Benz: A, C, CLA, GLA, GLB, GLC, and GLE Class, Metris

Mitsubishi: Outlander Sport

Nissan: Altima, NV200, Rogue Sport, Sentra

Polestar: 1

Subaru: Crosstrek, Impreza, WRX

Toyota: CH-R, Corolla, Supra

Volkswagen: Arteon, Atlas, Golf, Jetta, Passat, Tiguan

[u/Coffee-Not-Bombs]

I live in a town where 5.7L is probably the average displacement...

[u/[deleted]]

There are several reasons:

1) Modern 2.0 liters have adequate power for the average car buyer who just wants reliable point A-B transportation

2) They are more fuel efficient than larger displacement engines, at least in a small car

3) they generally weight less than larger displacement engines with more cylinders

4) they are cheap to manufacture vs a larger displacement engine with more cylinders

[u/LemursRideBigWheels]

Displacement taxes in major markets would be my assumption...that said an 8 liter 4 cylinder engine would also be a horrible idea outside of old time cars....

[u/WabbitCZEN]

Without having watched, I'd have to say balancing power with fuel economy is a lot easier.

[u/Trades46]

A 4cyl engine with 0.5L per cyl are still the golden balance between power, size, MPG, smoothness and adaptability that all other engine sizes cannot match.

[u/Slyons89]

The primary reason is that vehicles are taxed based on engine displacement in most countries. Some manufacturers are going down to 1.6 liters as max displacement for the same reason (Peugeot).

Also every manufacturer is putting 2.0 liter / 2.0 liter turbo engines in most vehicles simply for ease of production. If the same engine serves the needs of almost all of your models, you only have to spend the resources to set up manufacturing one type of engine, instead of multiple production lines for several engine types. With more and more resources being dedicated to EV production investments, manufacturers need to pare-down their range of offerings in gas engines.