Features - Technical
MAY 20, 2001
Electromagnetic Valve Actuation (EVA)
BY PETER WRIGHT
For any new technology to be used in Formula 1, two conditions must be met: Is there a net benefit, and is it feasible?
LVA is being developed for road engines, where it makes a lot of sense. The brochure figures for an engine quote maximum power, occurring in the range 5500-8000rpm, whereas most drivers (except insidef1.com readers!) drive in the 2000-4000rpm range. To achieve the brochure figures requires high valve lift and long valve duration, while cruising in high gear or ambling along in traffic requires lower lift and different valve timing, settings optimized for low fuel consumption and emissions. Throttling a petrol engine generates significant pumping losses, whereas reducing valve opening times and valve lift provides a much more efficient method of modulating the power output. Many modern engines have variable valve timing systems (VVT), and methods of varying lift are being explored. EVA solves all these issues at one go. Using electromagnetic solenoid actuators to open and close the valves permits infinitely variable valve lift and timing.
Formula 1 engines are normally operated in the 15,500-17,500+rpm range, with peak torque available from around 13,500rpm. In 1996, Boretti (Fiat Research), Borghi (University of Bologna), and Cantore and Mattarelli (University of Modena) - surely Ferrari inspired - published an SAE paper on optimizing a racing engine by, among other methods, variable valve timing and lift. On a "paper engine" that represented a 3l, V12, optimizing valve timing and lift for all RPM between 6,000-19,000 showed benefits below 8,000rpm, but little difference above that figure.
Mario Illien, Ilmor-Mercedes, has gone on the record against LVA on the basis that the power consumption would be too great. The need to accelerate each of the 40, 40gm (1.4oz) valves and associated hardware at around 4000g requires an actuator force of 1600N (360lbf). He also stated that valve to piston clearances are around 0.2mm (0.008 in) and so the precision needed in controlling the valve position would be problematical. Also, the heavy electromagnetic coils and magnets would be above the CofG of the engine and so raise it overall.
So, little benefit versus questionable feasibility means LVA is most unlikely. However, while Renault struggle with whatever they have in their engine, I do wonder what BMW are doing that gives their engine in the Williams higher RPM and power than the oppositionÉ.