Hello, everyone and welcome we are inside of the 2018 Volkswagen Tiguan. This is Volkswagen's first model
which is running their new EA888 engine running the new Budak cycle,
this new engine cycle which Volkswagen has developed it was named
Budak cycle by Volkswagen after their powertrain engineer who developed it. Now this cycle is basically a variation of the modern Atkinson cycle,
which is a variation of the Miller cycle without a supercharger, so what does all this mean?
Well that's what we're gonna get into in this video. How does this engine work?
Why is it more efficient? That kind of thing. So in order to understand that we need to understand the Atkinson cycle,
and the modern Atkinson cycle what it is is during your intake stroke,
everything happens as normal your intake valve opens your piston moves down it pulls in that air fuel mixture
now during the compression stroke you leave that intake valve open for a short duration,
so you're pushing out some of that air some of that intake charge and what this does is it lowers your effective compression ratio
so now your compression ratio is smaller than your expansion ratio
because your expansion ratio has remained the same that never changes now by having a lower compression
ratio than your expansion ratio. You're able to extract more useful work out of it
so the whole idea is the piston has a longer distance to travel down and expand outward than it is
compressing that gas so more of the energy from combustion is turned into useful work the ultimate goal
is that the at the bottom dead center of the Atkinson in cycle, what happens is you're at atmospheric pressure
that's the ultimate goal. So that means you've turned all the available heat and pressure from combustion
into useful work
the Budak cycle, the cycle which Volkswagen has developed is
basically the same thing except instead of opening the intake valve for a longer duration you're closing that intake valve
sooner so during the intake stroke you're going to close that intake valve before that piston reaches bottom dead center now
this is effectively doing the same thing you're
reducing the amount of air that you pull in and as a result your compression ratio is less than your expansion ratio
and because of this of course you're going to have greater efficiency
so the specific output of the engine goes down when you're running this mode, but the efficiency goes up, so it's great
you know when you're cruising on the highway when you're at
low loads and Volkswagen has a solution for when you want power, so when you do want power. There's a cam
lobe switch, so there's this little pin that forces the cam to a
longer duration profile and actually a higher profile so you open the intake valve more and you open it for a longer duration and
so that's for this power cycle when you you know you put your foot down
you want full power from the engine it gives it to you
and it switches over to you know the normal Otto cycle that most engines out there are running
so they do have you know a pretty cool
visualization of this 3D model
and so I'll try to put these two intake strokes side-by-side and hopefully you can see the difference you know the intake valve
running the budak cycle closing sooner than you know when you're just running the traditional Otto cycle
and you know you want to make more power for that version.
So pretty cool that you know it's able to switch between these two different modes
it's not you know the most groundbreaking thing ever. They're just you know it's a it's a different
take on the Atkinson cycle, which is a way of increasing fuel economy so cool
they've taken another approach to it and you know come up with this clever solution to differ the expansion ratio from the compression ratio.
So has this engine cycle change been an effective means of increasing fuel economy? Well it certainly has improved from the previous generation Tiguan
but you're still only getting 27 miles per gallon on the highway
Even if you get the all wheel drive version or the front wheel drive version both of them getting
27 miles per gallon on the highway which for this segment you know certainly isn't class-leading the Honda CRV
the Mazda CX-5
the Subaru Forester all of those you know able to achieve the low 30 mile per gallon range on the highway
so they are able to do better than you know this engine cycle. This is a fairly heavy vehicle
so that probably plays a big role in its fuel
economy rating it is cool that they have improved it although you know compared to the competition
they're not exactly at the top. If you guys have any questions or comments feel free to leave those below. Thanks for watching!