British roadster prototype addresses rotary engine shortcomings
What Advanced Innovative Engineering (AIE) lacks in creative company naming skill, it makes up for in its passion for advancing rotary engine technology. Its compact, lightweight 650S Wankel engine promises to alleviate problems with rotary design while offering the superior power-to-weight ratio rotaries are known for. The engine's small, lightweight size makes for easy integration within vehicles like the cherry red roadster AIE put to the track last week.
Mazda may be the most famous automotive force behind the rotary engine, but it's not the only one out there with some interest in bringing the rotary roaring back. In June, we saw the LiquidPiston X engine and the Mini go-kart, and now we have a more adult-sized go-kart sporting a different breed of developmental rotary.
AIE was established about four years ago with the objective of advancing rotary engine design. Its Wankel engine design began life as the patented work of David Garside, famous for his rotary experience at Norton Motorcycles, and AIE is further developing it for use in automotive, aerospace and marine applications. Specifically, it hopes to overcome the rotary's well-known drawbacks, like poor fuel economy and emissions performance, while capitalizing on power-to-weight advantages.
The pillar of AIE's Wankel design is Garside's Self-Pressurizing-Air Rotor Air Cooling System (SPARCS), which uses gases from combustion to help in cooling. The company claims this technology prevents excessive oil losses by continuously recirculating oil, provides better thermal stability for improved efficiency in operation, and decreases strain on the seals and engine components.
"The SPARCS cooling system for Wankel rotary engines utilizes the self-pressurizing blow by gases from the combustion process (which have escaped into the interior of the engine's core via the rotor's side seals) as a cooling medium," AIE explains of its design. "This pressurized air-gas mixture is recirculated in a completely closed loop circuit by an internal fan which is driven by the main shaft. As it recirculates, the air-gas mixture passes through the engine's rotor where it picks up heat before then being ducted through an external heat exchanger to reject the heat."
AIE makes a number of SPARC-cooled rotary engines of different sizes, and the one used in its roadster is the 650S, a 650cc (40 cu in, 0.65 L) unit that puts out up to 120 bhp (89 kW) and 80 lb-ft (108 Nm). It measures 19.6 x 16.5 x 15 in (498 x 420 x 383 mm) and weighs 62 lb (28 kg), numbers AIE reckons make it 50 percent smaller and lighter than a comparable four-cylinder engine.
For the past year, AIE has been working with automotive structural manufacturer Axon Automotive, whose tech was used in the Hyundai Intrado concept's carbon frame, and niche sports car maker Westfield Sportscars, whose work also includes the all-electric iRacer on a clean-driving, lightweight rotary roadster. The 650S rotary replaces the four-cylinder engine typically found in the Lotus 7-inspired Westfield roadster, held in place by an Axontex carbon fiber-based structure.
"By partnering with Axon and Westfield, we want to demonstrate that it is possible to build a sports car that is both lightweight and great to drive," Axon managing director Nathan Bailey said of the project when it was announced last September. "By reducing the overall weight of the Westfield vehicle, this project will prove that a sports car doesn't need a heavy piston engine in order to deliver exciting performance."
The 650S-powered Westfield is still a prototype, and after appearing at various 2016 shows, including the Goodwood Festival of Speed, it made its dynamic debut last week at the 2016 Cenex Low Carbon Vehicle Event.
AIE has been generating interest in its rotary engines by touring around with the rotary roadster, and it plans to continue testing and improving the 650S's efficiency. In addition to working on rotary engines for directly powering cars and other vehicles, it is also exploring using its engines as range-extenders in electric vehicles.
You can hear the rotary grumble and watch the car do its thing at the Millbrook Proving Ground in the clip below.