Owens to supply Radical Sportcars with Turbos
Leading forced induction specialist and BTCC control turbocharger supplier Owen Developments has an exciting new project to announce in conjunction with Radical Sportcars on their new supercar-slaying RXC Turbo.
In 2013 Radical announced the RXC, a new track day car with the aim of being the fastest thing on the road, with a naturally-aspirated 3.7 litre Ford V6 it immediately showed it was a game changer. A year later Radical announced there would be a new version of the RXC with improved aerodynamics, power, and a new AER prepared twin-turbo engine, which is where Owens were approached and our involvement began. Having worked on similar projects previously, such as developing race turbos for the BTCC and Formula 2, as well as OEM fast road projects like the Mitsubishi Evo IX FQ400 and the Subaru Cosworth Impreza STI CS4, Owen Developments have the experience and facilities to realize the project.
In partnership with Radical, Lee Owen (Director of Turbochargers) has led the development of twin-turbos for the RXC. The brief was specific in what Radical were looking for in these turbos; they needed more power than the standard turbos on the V6 but greater emphasis was on power delivery. In such a light car very fast spooling turbos, such as the ball bearing Mitsubishi Evo units Owens are famous for, would create an almost undriveably aggressive power curve. Creating a specification which would make good power at the top end, not spool too soon or too aggressively and still fit in the standard housings with minimal modification would be a challenge.
“It’s an interesting challenge as we would usually prioritise response, they [Radical] knew that if the boost and power could come in progressively and predictably the car would be much better for it. The wastegate modifications and actuators took some fine tuning but now the turbos come on very smoothly.”
-Lee Owen, Director of Turbos
To satisfy these demands two new HTA™ billet aluminium compressor wheels had to be developed; nothing this size had been made before! Not only that, but one of the turbos would have to counter-rotate meaning a ‘mirror’ of the wheel would have to be manufactured as well. These wheels put greater forces through the turbo than the standard parts, so in the interests of reliability Owens re-engineered the turbo to run a 360° thrust bearing that features a greatly increased surface area on the bearing.
“I wouldn’t say the power comes with a mighty kick. It’s more a surge - that just keeps surging. When you bury the throttle the noise grows and the power comes in gradually and just keeps coming. You don’t think it will ever end. It’s the immediacy of it that surprises.”
-Scott Malvern, Motorsport News
The turbine wheels and wastegate were heavily modified as well to dramatically change how the turbo spools and delivers power, this was integral to realising the progressive power curve envisioned by Radical. The modifications to the wastegate neccesitated custom acutators being developed too, as the standard parts could no longer control the wastegate accurately.
With this turbo set-up the RXC Turbo has some astonishing performance figures; 0-60mph times of 2.6 seconds, 483hp/ton and a top speed on the exciting side of 180mph mean it will no doubt set a new benchmark for road-legal track cars.
The RXC Turbo is available to order now from Radical.