At the 2014 Detroit Auto Show (NAIAS), the Lexus RC F made its global debut, and what makes it unique is the combination of the fuel-efficient Atkinson cycle technology with the conventional, more powerful Otto cycle to achieve fuel efficiency without compromising horsepower.
Image Credit: Nicholas Brown / Kompulsa.
This Otto-Atkinson cycle engine, uses the Atkinson cycle for lower speeds, and switches to the Otto cycle when more power is needed. This is a 5.0 litre, 450 horsepower (336 kW) engine which produces 384 pound-feet (520 Nm) of torque, therefore, it is most powerful Lexus V8 engine.
This advanced concept is nothing new, but was first introduced in a 1982 paper titled Luria et al by Tel-Aviv University and the Israel Institute of Technology.
The paper outlined test results which showed that fuel consumption of this Otto-Atkinson cycle engine was 19% lower. Nitrous oxide and carbon monoxide emissions were also lower.
According to Green Car Congress, there was another research paper from Ford where they ‘tested a modified 1.6L I-4 engine with retarded, but fixed, valve timings and increased, but fixed, geometric compression ratios to simulate the Otto-Atkinson cycle. The engine demonstrated 15% improvement in BSFC relative to the standard spark-ignition engine with 10% EGR at 1500 rpm, 2.62 Bar BMEP. Tests also revealed 50% reductions in BSNOx and BSCO emissions but a 60% increase in BSHC.’
Lexus hopes that this new Otto-Atkinson-cycle V8 engine will achieve greater fuel efficiency than the 18 MPG that the Lexus IS F sedan does, and as well as a 0-60 acceleration time of 4.7 seconds. Atkinson cycle engines were used in hybrid-electric cars such as the Toyota Prius, but it may have a place in non-hybrid cars as well, for those who aren’t ready to transition to hybrids.
Apart from that, this Lexus engine is coupled to a Sports Direct Shift Transmission (SPDS), and with a Torque Vectoring Differential (TVD), the first in a front-engined rear-wheel drive sports coupe. The TVD can operate in three modes, such as Standard for a balance of performance and stability, Slalom to enhance steering response, Track for consistent cornering behaviour while circuit driving, and finally, a newly calibrated VDIM that adds a vertical G-sensor to provide better vehicle stability.
The Lexus RC F will debut this fall with a price around $70,000 for a well-equipped model.
See an HD gallery of other cars from the NAIAS here.
Source: Green Car Congress.
