How the Bugatti Veyron Works
by Marshall Brain
Photo courtesy Bugatti Automobiles S.A.S.
The Bugatti Veyron
How would you define the most amazing production car in the world? Would it be:
The car with the most horsepower?
The car with the fastest top speed and acceleration?
The most expensive car?
At the moment, the Bugatti Veyron appears to have it all:
A W-16 engine that can produce 1,001 horsepower
A top speed of 250+ mph (400+ kph)
A zero-to-60 time of three seconds
A zero-to-180 time of 14 seconds
A price tag somewhere in the $1 million range.
In this article, we will take an in-depth look at this amazing automobile and see how it is possible to fit so much performance into a single machine. It all starts with the engine...
It All Starts With the Engine
The Bugatti Veyron is a car built around an engine. Essentially, Bugatti made the decision to blow the doors off the supercar world by creating a 1,000-horsepower engine. Everything else follows from that resolution.
Photo courtesy Bugatti Automobiles S.A.S.
The Bugatti Veyron features a 1,001-hp engine.
So let's start with the engine. How would you begin the design process for an engine this powerful? If you have read How Car Engines Work, you know that if you want to create a 1,000-horsepower engine, it has to be able to burn enough gasoline to generate 1,000 horsepower. That works out to about 1.33 gallons (5 liters) of gasoline per minute.
How much gas is that?
Here's a quick calculation, which you can ignore if you hate math:
1,000 horsepower is equivalent to roughly 2.6 billion joules per hour. A gallon (3.8 liters) of gasoline contains 132 million joules, so a 1,000-hp engine has to be able to burn just over 20 gallons of gasoline per hour.
However, car engines are only about one-quarter efficient -- three quarters of the gasoline's energy escapes as heat rather than as power to the wheels. So the engine actually has to be able to burn at least 80 gallons per hour, or 1.33 gallons (5 liters) per minute.
Let's convert over to metric. Gasoline requires about 14.7 kilograms of air to burn 1 kilogram of gas. Air weighs 1.222 kilograms per cubic meter at sea level. A gallon of gasoline weighs 2.84 kilograms. So the engine has to be able to process 2.84*1.33*14.7 kilograms of air per minute, or roughly 45 cubic meters of air per minute. That's 45,000 liters of air per minute.
If a V-8 engine is turning at 6,000 rpm, it can inhale a total of 24,000 cylinders' full of air per minute. If it needs to inhale 45,000 liters of air per minute, it works out to roughly 2 liters per cylinder-full. That's a 16-liter engine.
We need a 16-liter engine to burn 1.33 gallons of gas per minute. That actually makes sense -- the engine in the Dodge Viper is 8.0 liters in displacement and produces 500 hp.
But there's a problem: A 16-liter V-8 engine would be very large. And the pistons would be massive, so there would be no way it could turn at 6,000 rotations per minute (rpm). It might turn at a maximum of 2,000 rpm, meaning that you would need an immense 48-liter engine to generate 1,000 hp. Clearly an engine that big is impossible in a passenger car.
So how did Bugatti fit 1,000 horsepower into a passenger car?
The Engine: Creating the Magic
Photo courtesy Bugatti Automobiles S.A.S.
Bugatti did two things to create a compact engine capable of producing 1,000 hp. The first and most obvious thing is turbocharging.
If you have read How Turbochargers Work, you know that one easy way to make an engine more powerful without making the engine bigger is to stuff more air into the cylinders on each intake stroke. Turbochargers do that. A turbo pressurizes the air coming into the cylinder so the cylinder can hold more air.
If you stuff twice as much air in each cylinder, you can burn twice as much gasoline. In reality, it's not quite a perfect ratio like that, but you get the idea. The Bugatti uses a maximum turbo boost of 18 PSI to double the output power of its engine.
Therefore, turbocharging allows Bugatti to cut the size of the engine from 16 liters back down to a more manageable 8 liters.
To generate that much air pressure, the Bugatti requires four separate turbochargers arranged around the engine.
Photo courtesy Bugatti Automobiles S.A.S.
Engine and air snorkels
The second thing Bugatti engineers did, both to keep the RPM redline high and to lower lag time when you press the accelerator, was to double the number of cylinders. The Bugatti has a very rare 16-cylinder engine.
There are two easy ways to create a 16-cylinder engine.
One way would be to put two V-8 engines in-line with each other. You connect the output shaft of the two V-8s together.
Another would be to put two in-line 8-cylinder engines beside one another.
The latter technique is, in fact, the way Bugatti created its first 16-cylinder cars in the early 20th century.
For the Veyron, Bugatti chose a much more challenging path. Essentially, Bugatti merged two V-8 engines onto one another, and then let both of them share the same crankshaft. This configuration creates the W-16 engine found in the Veyron. The two V's create a W. You can see exactly how this looks in a set of beautiful videos available on the Bugatti Web site (click here for instructions on how to access the videos).
Then, Bugatti started piling on features to make the engine even better.
The Engine: Special Features
The special features of the Bugatti W-16 engine are amazing. For example:
The engine has four valves per cylinder, for a total of 64 valves.
It has a dry sump lubrication system borrowed from Formula 1 race cars, along with an intricate internal oil path to ensure proper lubrication and cooling within the 16 cylinders.
It has electronically controlled, continuously variable cam timing to create optimal performance at different engine rpm settings.
It has a massive radiator to deal with all of the waste heat that burning 1.33 gallons of gasoline per minute can generate.
Everything about the engine is superlative.
And it is remarkably compact. It measures just 710 mm (27 inches) long, 889 mm (35 inches) wide and 730 mm (28.7 inches) high. This is the beauty of Bugatti's W-16 approach -- the engineers managed to fit 1,000 hp into a reasonably sized package.
In order to harness all of this horsepower and torque, you need an amazing transmission...
