Hello everyone and welcome in this video we are talking about dynamic skip fire
which is a technology
which seeks to improve the efficiency of
engines and now the interesting thing about it is the larger your engine the more cylinders your engine has
the greater the effect that this has now that's not to say that smaller engines aren't more efficient
they tend to be more efficient
they tend to get better fuel economy numbers
so this technology isn't going to make you know an already super efficient small compact engine more efficient
but it will bring a larger engine closer to those fuel economy numbers
so that's the goal with this technology and essentially what it does is it gives you fully variable cylinder deactivation
so let's say you have a v8 engine
well you can run on one cylinder or you can run on eight cylinders
or you can run on any
combination of cylinders in between
so that's kind of the beauty of this is it allows you to run on any number of cylinders
and it's the theoretical limit of what cylinder deactivation can be and how it can improve
your vehicle's fuel economy through cylinder deactivation.
So how does it work first of all? And the way we're going to discuss is by closing off the intake and the exhaust
valves and there are many ways to you know stop an intake or exhaust valve from working
we're gonna be talking about this one here using a locking pin, and so essentially we've got our cylinder
which is going to be right here Here's our intake valve
there'll be this similar system for both the intake and the exhaust valve so you'll be blocking off both of them on command for each
individual cylinder and so what's going on is you've got your camshaft like normal
and then you have this deactivation arm and so when it's normally operating as that camshaft rotates
there's a locking pin which acts as a hinge and you press down on that
deactivation arm and it opens up your intake valve nothing fancy there
now oil pressure is what's keeping that locking pin in place and then when you want to deactivate this cylinder
completely and it can do this in real time. So it says you know okay, the next cylinder
that's going to fire is this one do I want to fire it yes or no
and then it'll use this pin to
determine whether or not it's going to and so you'll have oil that will come in through this passageway right here it will press that
pin back so now it's no longer holding up that
deactivation arm so now as your camshaft rotates and it hits that deactivation arm
it pushes it down without pushing the valve down so it comes down here
pivoting more towards where the the valve is rather than pivoting where the pin is
so you don't open up that valve and as a result you do not fire that cylinder and again this can be done in any
combination with any of the cylinders that you have you only use as many cylinders as you need so if you're cruising down the highway
and you really only need the power from two cylinders
you only use two cylinders and also because this can you know dynamically change
which cylinder is firing it can actually choose an order of firing that makes sense in order for the engine to be well balanced so
versus traditional cylinder deactivation
control methods where you may just use four cylinders or eight cylinders
this is actually going to provide you better balance and better fuel efficiency now looking at a four cylinder as an example
why is it more efficient to run on one cylinder than running all four cylinders for the same amount of power needed?
So let's say you need to produce 25 horsepower.
Why is it more efficient to run one cylinder then four cylinders each producing less than 25 horsepower?
versus one producing all of that 25 horsepower
well the reason the main reason is it comes down to having a significant reduction in pumping losses
operating with just that single cylinder
and so if you think about it from a throttle standpoint if you're just running on one cylinder
your throttle is going to be pretty wide open in order to get enough air for just that one cylinder
versus if you're running a bunch of different cylinders
you don't need all that much air because you have all four of them operating so your throttle is going to be you know relatively
closed in comparison to our example over here and with that throttle closed
I mean
there's it means your engine has to work harder to pull in that air so the pumping work
that an engine is doing essentially the pumping losses is a
function of you know the pressure of the exhaust minus the pressure of the intake
multiplied by volume and so
looking at it as a function of you know the pressure at the exhaust and the pressure at the intake if
you can have that intake pressure really high as you can see this number here will decrease that means your pumping losses are less
or if you can have your
exhaust gasses your exhaust pressure really low then that means this number here is also lower
so you're pumping losses are lower so that means you're
maximizing the amount of energy if you get all of that pressure turned into useful work when you open up the exhaust valve there's no
pressure left to push out of course, that's not realistic
but that's the ideal version and
then same with the intake if your engine doesn't have to work very hard to pull in that air because the pressure outside of it
is already really high
then it's going to operate more efficiently and so that's the huge benefit with using just a single cylinder
and having that throttle open so you reduce your pumping losses
and you don't have to have as much pumping work required versus having that throttle partially closed
it's actually acting you know a lot like a damper in a way where it's requiring energy
it's putting heat into the air as you pull it through requires that engine to work harder to do it
another reason is by operating at low loads
it's actually not as efficient
from a you know within the cylinder how much heat is rejected to those cylinder walls
so you're not creating as much heat in each of those individual cylinders
but the percentage of that heat that is lost to the cylinder walls is
greater when you're operating at low load conditions rather than when you're operating at higher load conditions
engines operate more efficiently at higher loads
but of course you're using more fuel and you're creating more power when you do that so by deactivating
several of the cylinders you're creating a smaller amount of power you're not creating as much efficiency losses
and you're operating so you're getting better fuel economy
while maintaining the power that you need
now as mentioned the more cylinders you have the more effective this becomes so let's say you have 16 cylinders
but you only need a little bit of power well that means if you're running all 16 cylinders your throttle is going to be nearly
closed so you're pumping losses are huge
and you're running all 16 of those cylinders versus if you're running just a single cylinder out of those 16
your you know you're pumping losses are very low and your efficiency is greater the other thing is because you are closing off the valves
using cylinder these valve
deactivations
for both the intake and the exhaust in the cylinders that aren't firing you don't have pumping losses because you're not actually moving any air
through it so that's another advantage of using a system like this where you do activate it by deactivating the valves
so you don't have those pump losses associated going through those cylinders, which aren't firing now
what does this mean for fuel economy and for emissions?
well
Delphi is saying that you can expect 7 - 15% reduction in co2 emissions and a 10 - 20%
improvement in fuel economy
and you know this number will be larger depending on the size of the engine
smaller four-cylinder engines aren't going to see as much of an improvement as bigger
V8s V12s things like that so now that you all understand how it works
you can let me know in the comments that because it's complicated it will fail. It's unreliable
it's a dumb idea all those kinds of things
thank you so much for watching if you have any questions or comments feel free to leave them below.