Hello everyone, and welcome. In this video
we're going to be talking about why no
production vehicle has ever joined the
300 mile per hour club, and to do this
we're going to be analyzing the Bugatti
Veyron. For a couple of reasons; first of
all, it once did have the production top
speed record, and second of all, there's a
lot of data out there available for it.
The Bugatti Chiron would be great to
analyze but not all the data is out
there yet. So looking at the Bugatti
Veyron has a drag coefficient, when it's
in top speed mode, lowered down, of 0.36,
this is versus 0.41 with a top speed
of 230 miles per hour when it's not in
this top speed mode. Frontal area of 2.07
meters squared, or 22.3 feet squared.
A weight of 1888
kilograms or 4162 pounds. So, the first
thing we're going to do is find out how
much power does this vehicle need to
overcome aerodynamic drag, in order to
reach 300 miles per hour. Power is equal
to force times velocity, so if we find
the force of drag, multiply that by three
hundred miles per hour, that will give us
how much power we need to overcome
aerodynamic drag alone. That's equal to
one-half Rho, which is the density of air,
at sea level this is 1.225 kilograms
per meter cubed at 15 degrees Celsius,
multiply that by velocity squared times
our drag coefficient 0.36, multiply
that by our frontal area, and then
multiply that once again by velocity so
i changed the velocity here from miles per
hour or from km/h to 134.112 meters
per second.
Now, you know, you may also be wondering,
you know, what's the equivalent of three
hundred mile per hour club on the metric system,
483. I'm sure a lot of you out there have
wondered, you know, why has no car ever
hit 483 km/h and that's what this video
is about. Great, so we do that math we get
1.101 megawatts, or 1476 horsepower.
That's how much horsepower we
will need just to overcome aerodynamic
drag. Now moving on, power to overcome
rolling resistance. We need that, once
again, force times velocity. So, the force
of rolling resistance is equal to the
coefficient of rolling resistance
multiplied by the normal force, and then multiplied by
our velocity, to get power. Now, this is using
a conservative high estimate of
0.015 as the coefficient of
rolling resistance for a tire,
I'm just kind of assuming it's a sticky
tire that has high rolling resistance,
multiplying that by 1888, that's the mass
of the vehicle, times 9.81 meters per
second squared, times our top speed of
300 miles per hour, or 134 m/s. That gives
us 37.26 kilowatts, or about 50
horsepower, which we'll need just to
overcome rolling resistance. So we can
add those two together and we will know
that, at the wheels, we'll need 1526
horsepower, and so here's where we get
into some bad math, admittedly. We're
just going to assume a 15-percent power
loss through the drive train. Now, this
will be different for every single
vehicle, and really the only way to find
this out is to dyno your specific engine
and then dyno your specific vehicle at
the wheels, separately. Then, you can
determine, you know, how much power did
you lose through the drivetrain. That's
really the only way to do it, it's going to
be unique to every single vehicle. Using
fifteen percent as a general rule is
dumb.
However, I have included a link in the
video description, which goes into great
detail about where all of those power
losses occur, and kind of general
percentages. Gets into, you know, very
fine detail of where this power loss
comes from, this fifteen percent, depending
on the vehicle. So, worth checking out, I'll put
that in the video description, and so if
you take 1526 divided by 0.85, assuming a
15-percent power loss, that's going to
give us about 1,800 horsepower, which
we're going to need at the engine, or
1.34 megawatts at the engine, in order to
reach 300 miles per hour.
Ok, now, some of the information that
comes from this link, which I'll be
referencing in the video description, is
you know, how much power is actually
generated by the engine, how much power
of that is completely wasted. So, one of
the figures a Bugatti has, you know, said about
the Chiron is that, although it
produces 1,500 horsepower, and has about
3,000 horsepower that it needs to reject
the heat. And, so you know, this is done
primarily through two
methods; you've got a cooling system for
your engine, and then you, of course, have
the exhaust, your exhaust is just
spitting out heat. Hopefully you recover that,
that's a great thing about turbochargers
can help recover some of that energy, and
then you of course have the cooling
system to reject that heat. So, when
you're driving a vehicle that has this
much power, you need a lot of cooling,
because you know, 3,000 horsepower of
heat is no joke.
And so, part of the reason why this has
such a crappy drag coefficient, it's
actually extremely impressive, you just
don't realize it, because you know it
looks the exact same as a Cadillac
Escalade. Cadillac Escalade has a drag
coefficient of 0.36, so does a
Bugatti Veyron in top speed mode. The
reason why this is so high, and why this
one isn't, you know this actually
isn't that good for an Escalade, this is
extremely good for a Chiron. Ok, it's
still okay, like I shouldn't bash them,
they certainly know what they're doing, but
the point is, you're gonna have a
significant amount of drag,
just because of cooling, when you have
engines this powerful. So, you've got all
of these you know different ports on
there, the Bugatti Veyron has something
like ten radiators, ten heat exchangers,
and so you've got all these airports on
your vehicle, to be able to suck in that
air, and sucking in that air and passing
it through these heat exchangers creates a
lot of drag, and so that's why it has
this drag coefficient of 0.36. So if
you can lower this, you could reach that
top speed with significantly less power,
but it's very difficult to do. So, you
could, theoretically, create a production
vehicle that doesn't have adequate
cooling, which has a very low drag
coefficient and could get to 300 miles
per hour with far less than 1,800
horsepower but it would probably
overheat, and it wouldn't last very long,
and you wouldn't want to put a warranty
on that vehicle, because it's going to
overheat and it's going to fail. So,
cooling is one of the biggest reasons,
one of the biggest drawbacks of reaching
300 miles per hour, because you have to
have enough air flow for cooling your
vehicle, while simultaneously enough
power to reach that top speed,
so those kind of battle against
each other. And another important thing
to mention is tires. So the Veyron uses
special Michelin Sport 2 tires, they
need to be perfectly balanced, so you don't have any
vibrations at these ridiculously high
speeds, and they need to be able to hold
together, you know,
maintain the shape, maintain their
contact patch on the ground at extreme
G's. And an example, you know, an extreme
example is the Bloodhound SSC, which
uses aluminum wheels,
there's no rubber on it, they're going
for the land speed record. Not a good
idea for road cars, because you don't
really have any traction with an
aluminum wheel, but if you're just going in
a straight line, it's smart to do, because
an aluminum wheel will hold together,
whereas the rubber at those G-forces
that it's experiencing is just going to
kind of shred apart. So, hopefully this has
been interesting. My prediction is
that we won't see a car reach 300 miles
per hour, until, you know, it's going to
have to have at least 1,800 horsepower.
it could be less, you know, depending on
aerodynamic drag. This is the big,
critical part here, is getting
aerodynamic drag down. That dictates this
horsepower for the most part, as you can
see 1,500 horsepower alone is just
overcoming aerodynamic drag, so if we can
lower that drag coefficient, we can get
in below 1,800 horsepower, but as I
mentioned, cooling drag is playing a huge
role here, because there's so much heat
to reject. So, thank you guys for watching.
If you have any questions or comments,
feel free to leave them below.