Hello everyone and welcome!
in this video, We are talking about how Audi is
eliminating turbo lag through the use of the world's first production electric supercharger.
So, traditionally, superchargers are run off of the engine. In this case, the engine is powering a three-kilowatt generator,
which is powering a 48-volt battery,
which is then powering a seven-kilowatt electric motor, which is powering the compressor side
That compressor to pull an additional air to compensate for turbo lag.
So Audi is calling this an electric-powered compressor, you can think of it as an electric supercharger.
Where instead of the engine driving it, you have an electric motor driving that compressor wheel
So first I want to talk about the air flow.
Looking at the engine it can look a bit complicated as what's going on, so I've broken it down here on the whiteboard
so we can kind of figure that out.
So, initially, you're just pulling in the air through one of those turbochargers.
So you've got your air filter, the air comes through that first turbo charger, a valve for the second turbocharger is off.
Blocked off so you can't have air coming through there. That air then travels split between two different intercoolers,
and then at this intercooler this valve will be open right here. Let's say
we're not using the electric supercharger, then the air passes through comes, combines, and then it's split between the two intake manifolds
for each of the cylinder banks
Then it goes from all eight of these cylinders to this single exhaust right here before passing out the back.
Now, we'll get into the different stages as it gets that into higher rpm,
but essentially how this electric supercharger works is, when you initially press on the gas you want that
instant response. You don't want turbo lag and so that's where the electric motor comes in.
In less than a quarter of a second it can spool up to
70,000 rpm and provide that immediate boost to fill the delay of turbo lag before, you know, the main
turbocharger has started spooling up. So you'll have this valve closed off right here,
and then the compressor wheel will pull air directly, push that into the eight cylinders.
Now that's when you initially press on the gas.
As you start to get into you know those those low to mid higher RPMs,
the low to mid rpm range,
then you start to just rely on the turbocharger itself once those exhaust gasses have been built up
and you no longer need this electric supercharger to compensate for the lag.
So then you're just running on this single turbocharger.
And then as you start to get to that mid-range rpm, into the higher rpm, and you're still asking for full power,
they've actually split now where they'll power both turbochargers and in this case
You'll have air coming through both of them. This valve right here will be open so you're now pulling in air through both turbochargers,
you're powering both turbochargers,
and you'll have sufficient boost for that mid to high rpm range while
Operating under full throttle. So, they've also done a super clever thing here with the exhaust valves, and so, the way
It's split up is on the low rpm side,
you're only using a single exhaust valve for each cylinder and all of that air is being routed to the first
turbocharger. And then there's a variable valve system
Which will activate the second exhaust valve, and that second exhaust valve for each cylinder goes to the second turbocharger.
So, each cylinder has one exhaust valve that powers each turbocharger
and you'll just use the one exhaust valve for those low to mid rpm ranges,
and then you'll use both exhaust valves to power both turbos for that higher rpm
region where you want more power and you want to be able to take advantage of using both turbos.
So it will act like a single turbo engine low to mid, and then mid to high rpm it will act like a twin turbo engine
as it splits that exhaust gases
into both of them.
Now a lot of people wonder why you can't just slap on an electric turbo on any car.
You've got a 12-volt battery system,
why can't you just use that to you know bring in more air?
And really it comes down to power so those,
there are aftermarket ones that'll say, like, it's an electric supercharger and it's powered off your 12-volt battery.
Those are nonsense, they don't have enough power to actually do anything.
And so that's what I kind of want to discuss here. So, the reason Audi put in a 48 volt system
is to be able to power this seven-kilowatt motor.
You need a significant amount of power to pull in a lot of air, and to do that very quickly.
So power is equal to current X voltage. So if you have 145-amps, you multiply that by 48-volts,
which is what this battery delivers, and that gives you 7kW or 7,000W about 9.5hp.
If you're using a 12V system, you've got 145-amps X 12V, you're only producing 1.75kW
and, you know, this is a huge demand. Your car battery already has plenty of things it's powering. All the on-board electronics,
you know your HVAC system,
plenty of different things, your sound system,
so it's got its responsibilities on the car, the spark for the engine, in the case of gasoline engines.
It has its responsibilities and considering, you know, the idea of putting on an electric supercharger on top of that, just simply isn't feasible.
There's not enough power to do it. So that's why Audi added this separate 48 volt system,
and this means adding a lot of stuff to the engine. This is why it's not done on every car out there.
It's because it's expensive, and it could, you know, it's of course complicated to do so you're adding
You know you're adding a generator to the system. You're adding a
470-watt hour,
48 volt battery to the system, you're adding that electric supercharger to the system,
and all the associated piping that goes along with it, and you're also adding a DC to DC converter,
48-volt down to 12-volt for other on-board systems, and this is all in addition to the 12-volt battery system that's already on the car.
So, you know, this isn't something that can be cheaply done. Hence, It's in, you know, a super nice, expensive, Audi SQ7.
Really nice, quick, SUV. And so, you know, in a more expensive car it makes sense, in cheaper cars
It's not a simple solution, as of the added complexity and cost that goes along with it.
But I think one of the really important things to understand is that it takes a lot of power to do this.
It's not something that you can, you know, depend on a 12 volt battery to do for your car.
So, if you guys have any questions or comments, of course feel free to leave them below.
Thanks for watching!