Mazda3 SKYACTIV – Letter from lead engineer to dealers


Dear Mazda Dealer:

Greetings again! This is the second in my series of letters telling you what my technical team at Mazda R&D is working on, to help bring our revolutionary suite of SKYACTIV Technology to the marketplace.

About a month ago, I accompanied the PR team on a trip to Iceland, where they were hosting a select group of global media for the world’s first drive of the upcoming CX-5 SUV. I was so happy to hear what the media had to say about the vehicle, stating that it is the perfect interpretation of Zoom-Zoom in an SUV platform, with engine power, transmission performance, steering and ride and handling exactly what they would expect from Mazda. As we get closer to the scheduled launch of CX-5 just after the first of the year, I’ll have a lot more to say to you about CX-5 and its features and technologies.

In the meantime, though, I want to take the remainder of this letter to talk to you about the SKYACTIV-G engine that you’ll see in the soon-to-be-released 2012 Mazda3. In my next letter, we’ll discuss the SKYACTIV-Drive and SKYACTIV-MT automatic and manual transmissions.

Mazda has always been known for ground-breaking engine technologies – from the original rotary engine in the 1967 Cosmo Sport to the Miller cycle V6 in the late-1990s Millennia to the advanced work taking place in Japan and here within my team in the US on experimenting with hydrogen to power the RENESIS rotary in the RX-8. As incredible as those engines are, though, SKYACTIV-G may be an even bigger step forward.

The SKYACTIV-G engine is the result of 10 years of deep study into the combustion process that’s at the core of every internal combustion engine. By starting at this absolutely fundamental level, we were able to build this new engine from the inside out, optimizing every part to make the combustion itself as efficient as possible.

High compression ratios have always been the best way to extract the most energy from an engine, but insufficient control of the combustion process has always limited how high the compression ratio could be pushed before knocking. Our MZR 2.0-liter Mazda3 engine achieves 10:1 compression on 87 octane fuel, which was basically state of the art until now. By comparison, our new SKYACTIV-G 2.0 liter in the same car has pushed that to an incredible 12:1, while still running on 87-octane regular fuel (a Ferrari 458 manages 12.5:1 on premium).

In the CX-5, we designed the body to make room for a unique, race-derived exhaust manifold that lowers combustion temperatures, and with this manifold, we were able push compression to 13:1, still on regular 87-octane fuel. Formula One race engines run about 13.5:1, and they require exotic race fuel to do it. (In Europe and Japan, where our customers are more comfortable buying premium fuel, we will run 14:1 compression. Even Formula One cars can’t keep up with that!)

There are so many details that made this high compression and efficient combustion possible, but two of the biggest are the advanced direct injection system and volcano-top piston design. Injecting fuel directly into the cylinder at nearly 3,000 psi (our MZR 2.0 is a more conventional 43 psi) gives us incredibly precise control of exactly where the fuel ends up, and delivers the fuel in a fine spray that cools the combustion chamber and helps prevent knock.

The piston design, which has a big dome on top, with a little bowl carved out of it like the crater in a volcano, came directly from our millisecond-by-millisecond study of high-compression combustion. We learned that the initial flame was contacting the top of a conventional dome-topped piston, wasting energy, slowing the combustion process, and leading to knock. When we carved out the crater, the flame could grow efficiently without obstruction.

Its tiny details like this that make efficient combustion, and efficient combustion doesn’t just make better fuel economy, it makes more power too! The SKYACTIV-G engine and SKYACTIV-Drive automatic transmission, when paired in a Mazda3 sedan, will deliver the 58* (4.9L / 100km) mpg highway numbers that your customers have been asking you for. But those numbers are different from other companies’ 58 mpg numbers, because ours will include Zoom-Zoom – we do not ask our customers to choose between efficiency and fun to drive, we do not install rock-hard tires that take away steering feel and challenge ride and handling, and we do not believe in transmissions that are always two gears too high.

Have I lost you? Hope not. This is very complicated technology, I know, so I’ve tried to boil it down to a few key points that I’d like you to remember, and share with your staff and teams. I love talking about this technology, as well as the rest of the technologies that make up the SKYACTIV TECHNOLOGY suite, and will share more of my thoughts and experiences as we continue to develop them.

Technically speaking,


*MPG is listed in Imperial gallons.