How does a car like Koenigsegg Agera make more than a 1000hp with just a twin-turbo V8 whereas the Bugatti Veyron required a quad-turbo W16 for similar performance?
In: Technology
how much HP a super car makes is rather a moot issue. more cylinders and more volume and larger turbos doesn’t equate to more HP. there are both advantages and disadvantages to adding more turbos/turbo stages or using more cylinders in different configurations.
so the answer is basically that’s what type of engine the designer wanted to focus on. one wanted to use a W16 while the other wanted to use a V8. that fact by itself states nothing about what the performance should be except ~1000hp is what the manufacturer decided on.
in the jesko/chrion, a similarly speced engine, both now produce 1500hp instead of 1000hp.
First and foremost, Bugatti built a W16 explicitly for the purpose of “because they can.” That isn’t to say it’s not without it’s benefits, but the Bugatti has always been a halo car, designed to showcase Volkswagen’s finest capabilities.
Now to talk about the numbers.
Gasoline has an available energy density of about 45 megajoules per kilogram, about 10kWh per litre burned. A typical engine will extract 1/3 of that, so that 1 litre/hour corresponds to about 3kW output.
That means that to extract 1000hp, (736kw) you have to have a fuel flow of just over 245litres/hour – which at 15:1 air:fuel ratio means 3676 kg of air per hour – which at 1.225 grams per litre equates to roughly 3 million litres of air – or roughly 833 litres/second.
Rolls Royce did that with the Merlin engine by making it 27 litres – but to develop that power at a 1500rpm propeller speed (13 litres per revolution = “only” 260 litres at 1500rpm) they had to add superchargers to increase air pressure and run the engine at 3000rpm, gearing it down for the prop.
A Merlin engine won’t fit in the back of a Bugatti.
A heavily turbocharged 5 litre V8 can develop 1000hp but it would self destruct in the 12 minutes required to do a sustained speed run, what the manufacturer promises. No other car can promise to perform at it’s peak level for nearly so long. Making an engine strong enough to last would result in a very heavy engine. 1000kW generators, expected to run continuously, are the size of cars so they can run slow enough that they don’t suffer structural and material failures. Top fuel dragsters make 15,000 hp in a v8, but the engine has to undergo a complete tear down and rebuild after every single run.
Just some numbers I dragged up from a similar comparison, the Veyron produces 1184 hp at 6400 rpm using 8 liters of engine – that is 23.125 horsepower per liter per kiloRPM. A Konigsegg produces 1124 hp at 7300 rpm with 5 liters of engine – that is 30.8 horsepower per liter per kiloRPM. By increasing the number of cylinders, they reduce the load per cylinder and increase reliability.
Finally, I googled dyno charts for the two engines. You have to understand, it’s not about peak numbers, you need to look at torque and horsepower over the entire RPM range, it’s the area under the curve that matters. The W16 has a flat torque curve from 2,000 rpm onward, and horsepower absolutely skyrockets, and the Konigsegg just doesn’t compare.
The Koenigsegg Gemera has a 3 cylinder that outputs over 600hp by itself (and a hybrid motor to put it even further over the top).
The only way this is possible is simple. Boost.
The Koenigsegg Gemera has a 3 cylinder that outputs over 600hp by itself (and a hybrid motor to put it even further over the top).
The only way this is possible is simple. Boost.
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