Lexus combined the fuel-efficient Atkinson-cycle engine technology with the more powerful Otto-cycle in the new Lexus RC F, which made its debut at the 2014 North American International Auto Show. This combination of engine cycles results in improved fuel efficiency without sacrificing horsepower.
It is a 5.0 liter, 450horsepower (336 kW) engine which produces 384 pound-feet (520 Nm) of torque, making it the most powerful V8 engine in the Lexus lineup. Remember, the Lexus LFA has a 550 horsepower V10. But it’s not the engine’s horsepower that is impressive, but rather its ability to switch between two different operating cycles.
The Otto-Atkinson cycle concept is not new, having first been introduced in 1982 when Tel-Aviv University and the Israel Institute of Technology published a paper on it. It showed that fuel consumption of the Otto-Atkinson cycle engine was 19% lower. Nitrous oxide and carbon monoxide emissions were also lower, but performance stayed on par.
According to Green Car Congress, there was another research papers from Ford where “…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 can get better fuel economy than the current 18 MPG Lexus IS F sedan, while still delivering a 4.7 second 0 to 60 MPH sprint. . It’s a different take on technology that is increasingly geared towards hybrid or plug-in hybrid vehicles, but some people still haven’t accepted that hybrids can be performance cars. Better fuel economy is always a step in the right direction though.
Apart from that, this Lexus engine is coupled to a Sports Direct Shift Transmission (SPDS), and with a Torque Vectoring Differential, the first in a front-engined rear-wheel drive sports coupe. The torque vectoring differential has three operating modes, include Standard for a balance of performance and stability, Slalom to enhance steering response, and Track for consistent cornering behavior while circuit driving and 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.
Source: Green Car Congress