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The beating heart of Valkyrie is one of the most defining aspects of the car. Much is made of the Valkyrie project’s commitment to the very latest technology, but providing a superlative driving experience is the very essence of its existence. Nowhere is this ethos better exemplified than the all-new Cosworth-designed 6.5-litre naturally aspirated V12 engine.
There is something immensely special about a large capacity, naturally-aspirated V12. The sound, the linearity, the sheer romance of it all. In the design process, various engine configurations were given consideration. Naturally, turbocharging with a smaller capacity engine would have been a different route to achieve the same power. However that route would deny the Valkyrie the kind of searing throttle response, soaring soundtrack and thrilling purity that only a high-revving, naturally aspirated 12-cylinder engine can deliver.
In the early concept stages various powertrain configurations were considered for the Valkyrie, including V6, V8 and V12 engines with single-and twin-turbo forced induction systems.
Turbo-charging the chosen engine would have provided an attractive design route as the overall dimensions of the engine itself were physically small. However, the turbos would require the fitment of large intercoolers. In addition, their associated weight and increased cooling penalties would result in a more difficult engine to package in what was to be a very tight space due to the strict aerodynamic requirements.
Another configuration to look at would be a V6 engine but by definition would not be as well balanced as a V12.The reason this was critical was that increased levels of NVH (Noise, Vibration and Harshness) into the cabin would be exaggerated as the engine would be bolted directly to the carbon tub. This would have necessitated rubber engine mounts which, in turn, this would have meant a much larger and heavier rear subframe with which to mount engine, gearbox and rear suspension components. A spiral of doom when it comes to added weight and complexity.
Even though a V12 engine is larger and heavier, it would provide the necessary amount of balance and smoothness to facilitate being solidly-mounted to the carbon chassis.Remarkably, this saves weight and packaging space by being smaller, lighter and more aerodynamically efficient than the V6 option.And of course, you get the V12 sound track!When combined with the heritage, emotional sound and throttle response of a naturally-aspirated V12, this option was a no-brainer.
Like every aspect of the Valkyrie, the engine design has been approached exactly as that of a pure bred competition car. That is to say free from conventional budget and resource constraints and compromised only by the need to comply with requirements of road legality and emissions regulations.To say this is approach is unusual in car design, underplays it somewhat.
There was only one place to go to make it all happen: Cosworth.A name steeped in glory, Cosworth has been designing and building exceptional race and road engines for six decades. They are based in a small industrial estate in Northampton, England.They are a business best known for their extraordinary record of success in Formula One.They enjoy a total of 176 Grand Prix wins as an engine supplier to countless F1 teams. Its DFV engine is the single most successful racing engine of all-time.It has realised 167 Grand Prix wins accrued over more than 20 years. More recently Cosworth’s‘CA’ 2.4-litre V8 which made its F1 debut in 2006 revved to a remarkable 20,000 rpm which was the highest revving engine ever to compete in F1.
Cosworth also has a long standing relationship with Aston Martin thanks to its involvement with engine development for the One-77 -Cosworth (amongst other projects)The configuration of the engine was to be a 65-deg V12 displacing 6.5-litres, capable of revving to 11,100rpm and developing 1000 bhp and over 700 Nm of torque. This would make it the highest revving and most powerful naturally aspirated road car engine ever made, with a specific output of 153.8 bhp-per-litre.
To ensure it revs like no road-legal emissions compliant V12 before it, the AE69 has a 1.36 bore-to-stroke ratio, which means less moving mass and an unprecedented appetite for revs. Another nice little fact is that is has a pair of throttle bodies that are the largest commercially available in the automotive world. They feed the ravenous V12 with as much as 625 litres of air every second.
The 11,100 rpm redline has required the use of gear drive for the camshafts and oil pump. The high engine speed and aggressive cam profiles demanded the engine use an F1-style gear drive to the cams and Cosworth brought to bear its decades of experience to control the difficult dynamic behaviour of such systems resulting in a very compact and light weight solution.
One of the best examples of this optimisation is the billet-machined crankshaft, which is an astonishing 50 per cent lighter than the crankshaft used in the Aston Martin One-77’s V12 -itself a Cosworth-developed evolution of Aston Martin’s series production V12 and, for a time, the world’s most powerful naturally aspirated road car engine.
Once in production each engine is meticulously hand-assembled in Cosworth’s pristine facility by its most experienced ex-F1 personnel. The painstaking process takes some three man-weeks to complete. Once built, each V12 will be fully run-in and performance tested in Cosworth’s test cells prior to installation in the cars. They ensure that every engine make a minimum of 1001hp before it leaves their factory. It also means that the owner is spared the task of completing laborious running-in mileage, they are free to explore the Valkyrie’s full performance from the day they take delivery.
The very idea of making a new engine from scratch is a rare thing these days. To do so for such a short run of cars is simply remarkable. Is this possibly peak combustion engine? If so, what a way to finish.
Technical Highlights:
•All-new Cosworth-designed 6.5-litre V12 is the most powerful naturally aspirated road car engine ever made
•11,100 rpm redline makes it the highest revving production road car engine ever made
•Projected outputs of 1001 bhp at 11,000rpm and over 700 Nm of torque
•Remarkable specific output of 153.8 bhp-per-litre
•Engine is a fully-stressed member of the chassis, just like that of an F1 car
•48 valves, 24 injectors, 24 spark plugs and coils, twin throttles -the largest available
•At full power the engine consumes 625 litres of air every second
•Titanium connecting rods and inlet valves, low-friction DLC finger followers
•Billet machined crankshaft is 50% lighter than that of the Aston Martin One-77’s V12
•12 scavenge pumps refill the dry-sump oil system every 3.5 sec
•Each engine takes ex-F1 engine builders 3 man-weeks to build and prepare for fitment
•Every engine will be fully run-in and performance tested at Cosworth prior to installation
Occupancy harness – every 25k miles