Approaches to Combustion Engine Improvements and Electrification

Automotive World 2018: Keynote lectures of Mazda and Nissan



This report presents the approaches of Mazda and Nissan towards internal combustion engine improvements and electrification based on their keynote lectures at the 10th Automotive World event held at the Tokyo Big Sight exhibition center in January 2018. Below is the summary of the keynote lectures.


Mazda: Improvement targets for internal combustion engines and Mazda's challenges

Below is the summary of the keynote lecture by Mr. Mitsuo Hitomi, Managing Executive Officer, Senior Technical Fellow, in charge of the Technical Research Center and Integrated Control System Development of Mazda Motors Corporation.

Currently, Internal Combustion Engine (ICE) vehicles emit approximately 50% more CO2 compared to Electric Vehicles (EVs), but it would not be a wise policy to simply replace ICE vehicles with EVs from an overall CO2 optimization viewpoint. Electric power obtained from power generation methods with lower CO2 emissions first should be used to reduce dependence on coal-fired power plants. We should not only rely upon the electrification by EVs, but we need to try to reduce CO2 emissions by both power generation methods and automobiles, which have lower infrastructure costs and reduce CO2 more than just by the introduction of EVs alone.

If the real-world fuel efficiency of vehicles equipped with Mazda's Skyactiv technology can be improved by more than 10%, CO2 emissions will catch up with EVs, which use electricity supplied by average power generation methods. If fuel efficiency can be improved about 25%, it will even be able to catch up with EVs operating with electricity supplied from LNG power plants, which have the lowest CO2 levels. So, this is our target for the time being. A 25% improvement in CO2 emissions will be possible if heat insulation can be added to Skyactiv-X's SPCCI (Spark Controlled Compressed Ignition).

Emissions regulations should not be viewed in terms of individual emission numbers, but should be considered in terms of total optimization so that emission pollutants can be reduced more efficiently. Passenger vehicles emit 3 times the CO2 of cargo vehicles, however cargo vehicles emit 7 times the NOx emissions of passenger vehicles. For example, by slightly relaxing the NOx regulatory limits of passenger vehicles (with low total emissions), fuel efficiency can be improved by 10-15%; this alone will result in reduced CO2 emissions.


Nissan: Automobile engine innovation aimed at the next 100 years

A summary of the keynote lecture by Mr. Toshihiro Hirai, Nissan Motors, Corporate Vice President, Powertrain & EV Engineering, is presented below.

Nissan's Mid- and Long-Term Visions:

  • To reduce CO2 emissions by 90% by the year 2050
  • To reduce air pollutants to the zero level regardless of the emissions regulation
  • Expansion of fuel efficient vehicles with high efficiency ICEs
  • Promote the deployment of Battery EVs

When comparing the energy density of batteries and liquid fuels, batteries are still too large and too heavy to be installed on all vehicles.

As one method to improve the heat efficiency of ICEs, variable compression will be deployed by Nissan. Both high power and thermal efficiency is realized with variable compression by achieving an ideal piston movement through its multiple-link mechanism, reducing friction by the decrease of lateral force as well as reducing secondary vibration.

Nissan introduced e-Power, as a technology to change the role of the internal combustion engine. With e-Power, the ICE is used as a power generator to augment the power supplied by EV batteries. By narrowing the operating conditions of the ICE to where it operates only at regions of high efficiency, kinetic energy can be recovered in the same manner that a Battery EV recovers kinetic energy during deceleration.


Next-generation Mazda SKYACTIV-X engine with SPCCI technology
(Tokyo Motor Show 2017)
VC Turbo Engine with Variable Compression Ratio
(NAIAS 2018)


Related reports:
Mazda's next-generation SKYACTIV-X gasoline engine technology (Dec. 2017)
Tokyo Motor Show 2017: Mazda, Suzuki, Subaru, and Daihatsu's exhibitions (Dec. 2017)
Tokyo Motor Show 2017: Exhibits from Nissan, Honda, and Mitsubishi (Dec. 2017)
Nissan's EV Strategy: Introduce EVs in all major vehicle segments by 2022 (Sep. 2017)
The growth of xEVs and improvements to ICE vehicles (Part 1) (Jul. 2017)