Cosworth's secret: behind the scenes at the firm behind Bugatti, Aston Martin and F1 engines
In the face of ever-tightening emissions regulations, Cosworth stands alone in producing fully compliant, high-revving, naturally aspirated supercar engines. We ask: what’s its secret?
There's a real buzzword at Cosworth right now. I doubt that, ten years ago, anyone could have predicted that high-power, high-revving, naturally aspirated engines with double-figure cylinder counts would have a renaissance, or that the Northampton-based engineering firm would be the go-to company for the design, development and manufacture of such bespoke engines. But it most certainly is. It created and delivered the 4-litre V12s for the GMA T.50 and T.33, is in the process of finishing off development of the epic 8.3-litre V16 for the new Bugatti Tourbillon and is hard at work on the 15,000rpm V10 for the Adrian Newey RB17 hypercar.
Yet the most remarkable thing about all these engines is not their extraordinary specific outputs but that they
are fully emissions compliant. And this at time when, in the wider market, we’ve seen the near-universal adoption of turbocharging and a number of quite humble internal combustion engines being dropped because it’s too expensive to modify them to meet ever-stricter emissions standards.
> Bugatti Tourbillon: the 1775bhp, V16-engined Chiron successor
The engine that triggered this transformation is the 6.5-litre V12 that Cosworth built for the Aston Martin Valkyrie. Cosworth’s commercial director, Chris Willoughby, recalls the tendering stage: ‘We ran the simulation and told Aston Martin it would be emissions capable. And it’s not like you can be nearly emissions capable. If it’s not, the whole programme fails. Some more mainstream consultancies said it wasn’t an emissions feasible engine. We looked at the analysis again and thought, well, we think it is.
‘Everybody in the business had to hold hands on it. We battled through a few issues and got it to work. And the way the market responded to it, the fact it was a naturally aspirated V12 and the soundtrack was so
different, it opened the door to this sort of project. All of a sudden we’ve got an engine that meets all the latest
emissions legislation and we warranty it for 80,000km. Now, who else do you go to if you want that sort of engine? Suddenly, we’re the safe pair of hands and it’s transformed our business.’
For Willoughby, it brings to mind one of the company’s much-earlier successes: ‘When we look at our company
history, there are two things in my mind that were massive steps, that were transformative. One was getting
the work to do the DFV [the Ford funded and badged 3-litre V8 that powered a string of championship-winning
Formula 1 cars from the late ’60s to the early ’80s], the second was the Valkyrie engine. As a company we’ve tried lots of things. All these things that didn’t sort of fit, like aftermarket tuning parts in the United States, and a few that did – our drone engines are really good. But the whole hypercar thing is a really good fit. It’s actually similar to the racing. We made something like 1000 DFVs, and if you look at the Gordon Murray engine, we’re probably going to be into a similar order of magnitude. If you look at DFV performance, it’s actually a bit less than the Gordon Murray engine but the GMA V12 passes emissions, has an 80,000km warranty and it’s tractable – you can drive it around town and everything.’
Dr Florian Kamelger, who was appointed Cosworth CEO in the summer, comes with a background in hypercar sales. He says there are many luxury brands out there whose customers want a V12 or something similar. ‘At the end of the day, in this environment, it’s about what the end customer wants. People buying hypercars will tell you they want the least electrification possible: “I drive my Taycan to the golf club but at the weekend it has to be sound, it has to be combustion, it has to be noise, it has to be high revs, all those kind of things.”’
Cosworth’s background in developing race engines gives it a can-do attitude, he says. ‘There were many experts out there who couldn’t see the Valkyrie V12 meeting emissions. And I think the talent in-house here just thought outside of the box and established a way to do it. And it happened again with the V12 for the Gordon Murray cars, and with the Bugatti V16 too.’
Making high-revving engines presents technical issues that need to be solved along the way ‘like little science projects’, says Willoughby. Cosworth is in the final stages of development and productionisation of the Bugatti’s 8.3-litre V16, an engine that’s every bit as monumental in the metal as it sounds. Each cylinder head looks about three feet long, yet the engine will rev to 9000rpm, like a four-pot Honda VTEC or, more pertinently, the V12 in the new Ferrari 12Cillindri.
Picking up a Tourbillon camshaft, Willoughby points out the damper inside the cam drive gear, which was developed to mitigate a distruptive vibration. Another innovation is a multi-arm ‘spider’ that sprays oil on the underside of each piston to cool it, which partly explains why the V16 circulates two litres of oil a second. On another bench is a piston and conrod from the GMA V12. That engine revs to 12,100rpm and uses F1-style metal matrix pistons, formed from a lightweight and durable composite of silicon carbide reinforcement and aerospace aluminium alloys.
Willoughby recalls that when they were designing the V16, the VW Group wheeled in their powertrain engineers: ‘They listened to what we were saying, pored over the data and said, “These guys know what they’re doing.”
‘The really difficult bit in an emissions cycle is the first bit when the engine is cold,’ he says. ‘We do quite a lot of stuff to make sure when we inject that first bit of fuel, it burns really well. If you listen to how a Valkyrie or GMA engine cranks, it cranks up quite a high engine speed. What we’re doing is preparing the engine for that first fire to be a really good one rather than stumbling through the first half a dozen combustion events. We also run the engine in a condition that puts an awful lot of heat into the catalysts. It’s essentially running the ignition really retarded. With a lot of engines that will cause misfiring but our engines you just get a load of exhaust heat, which lights the catalyst, which means you get low emissions.’
Kamelger reckons Cosworth is in a sweet spot right now, building 600 to 700 engines a year, but has some capacity for growth, maybe into the low thousands. It takes about four years from clean sheet to finished engine, so any project started now would have to meet the even stricter emissions standards of Euro 7. ‘In it there’s a thing called lambda‑1, which means you’re not allowed to overfuel,’ explains Willoughby. ‘Most engines overfuel a little bit at peak power to make sure things like valve heads and the catalyst don’t get too hot. The new legislation says you can’t do that. So we’ve got a mule engine developing the next range of technologies so we can make Euro 7. What we don’t want to do is dial back the power. That’s culturally against what we do so we’ve worked out a couple of ways of bringing the exhaust temperature down without pulling back the power and we’ve now run through Euro 7 emission cycles on the mule engine, so we’re pretty confident we can deal with the next generation of emissions legislation.
‘Quite often what happens in a more mainstream programme is that the targets will get diluted. We never do that. We do a concept study and out of that will come a simulated power curve, and we won’t knock 10 horsepower off the top just to make life easy for ourselves. We’re going to try really hard to hit those numbers. The flip side of that is, on the Valkyrie, I think 950 was the programme target from the simulation. When we got the mule engine on the dyno we could see the opportunity to make a bit more power and we ended up delivering 1000 horsepower.’
On the dyno during our visit is the race version of the Valkyrie V12, detuned to meet LMDh championship regulations. ‘The performance target is significantly lower than for the road engine,’ says Willoughby, ‘so we’re re-optimising it for different things – fuel economy and suchlike. It’s an odd direction of travel, to be taking something that is such high performance in a fully certified way, and then taking it to the racetrack and pulling the performance down.’
A Cosworth engine that won’t be holding anything back is the 90-degree V10 for the track-only RB17 hypercar, which will rev to 15,000rpm. Helping it get there will be pneumatic valve closing, as seen on Formula 1 V10s of the early 2000s, one of which was the Cosworth 3-litre V10 that powered the very first Red Bull F1 car. Since the RB17 was announced, Lanzante, who put a 1980s TAG F1 flat-six into a 911, has said it will make the RB17 road-legal. I wonder who they could ask to make sure it meets emissions targets?
This story was first featured in evo issue 331.
