Development of a Flex Fuel Vehicle: Impact on Powertrain's Design and Calibration 2010-01-2087
The benefits of running on ethanol-blended fuels are well known, especially global CO₂ reduction and performances increase. But using ethanol as a fuel is not drawbacks free. Cold start ability and vehicle autonomy are appreciably reduced. These two drawbacks have been tackled recently by IFP and its partners VALEO and Cristal Union. This article will focus on the second one, as IFP had the responsibility to design the powertrain of a fully flex-fuel vehicle (from 0 to 100% of ethanol) with two main targets: reduce the fuel consumption of the vehicle and maintain (at least) the vehicle performances. Using a MPI scavenging in-house concept together with turbocharging, as well as choosing the appropriate compression ratio, IFP managed to reach the goals. Thanks to the adaptation of the inlet manifold, the intake camshaft as well as the piston and con-rod coupling, the 2L engine with a compression ratio of 10.5 delivers with RON 95 unleaded fuel a maximum torque of 290 Nm constant between 2000 rpm and 3500 rpm, and 142 kW at 5500 rpm. But the output reaches with ethanol-blended fuels 350 Nm between 2000 rpm and 3500 rpm, and 150 kW at 5500 rpm, this from 20% to 100% of ethanol. Such performances made it possible to change the gearbox ratios in order to reduce the fuel consumption. The combination of intake camshaft design, variable valve timing and increased compression ratio also improves engine efficiency at part load. Compared to the standard engine, the BSFC's improvement reaches 7% at 2000 rpm and 2 bar BMEP. The complete adapted powertrain and engine control unit are now mounted in a vehicle and the calibration task is taking place, on the basis of test bench results. Vehicle results should be available for the coming autumn.