![]() They knew that a higher compression ratio would increase fuel efficiency and economy, but that detonation would be a problem if the temperature and pressure in the combustion chamber was too high for regular gasoline or even premium pump gas. Mazda engineers knew this when they designed their new SKYACTIV-G engines. Consequently, they have to burn some type of high-octane racing fuel to minimize the risk of detonation. ![]() However, most racing engines are carbureted or port injected and do not have direct injection or Variable Valve Timing (VVT). With 112-octane racing gas, the compression ratio can be bumped up to 14 or 15:1. Leaded racing fuel rated at 107 pump octane can usually handle compression ratios in the 12:1 range. These engines are burning super high-octane racing gas or some type of alcohol (methanol or E85 ethanol) and have rich air/fuel mixtures. Many high-performance racing engines run compression ratios of 14:1 or higher, but not on ordinary pump gas. So how can Mazda SKYACTIV-G engines burn regular 87 octane gasoline with a static compression ratio of 13:1? It’s Mazda magic! If the fuel lacks enough octane to handle a higher compression ratio, it will detonate, knock and cause a loss of power - and possible engine damage, too! Raising the compression ratio of a gasoline engine also improves its thermal efficiency, power output and fuel economy.īut as compression goes up, so do the octane requirements of the fuel to resist detonation. Diesel engines are typically about 30% more efficient than gasoline engines partly because of their significantly higher compression ratios (16:1 or higher for diesels versus 9:1 or 10:1 for most gasoline engines). The secret to Mazda’s fuel economy gains with its SKYACTIV-G engines is in its approach to combustion management. ![]() These engines include the SKYACTIV-G 1.3L engine in the 2012 Mazda 2, the 2.0L in the 2012 Mazda CX-5, and the 2.0L and 2.5L engines in the 2014 Mazda 6 and CX-5. In my view it makes it not fit for purpose, and I would add that there is no excuse with current technology for it not to perform much better than this.Introduced in 2011 in the Japanese market, Mazda’s ultra high-compression, direct injection gasoline engines are achieving fuel economy numbers that rival many hybrids - and at much less cost. When I complained to the Mazda service centre, they just shrugged their shoulders and said "that is a limitation of the system"!! There have been many similar examples, in each case I have had to resort to Google maps on my smartphone to find the actual destination! When I drove to it the SatNav told me I had arrived at my destination about a 1/3 of a mile away from their road, had not known where they lived I would have been completely lost, as there were at least two more turns and differently named roads to navigate before getting to theirs, I would expect it to at least get you to the end of their road. The SatNav found their postcode and road name, which I selected, it gave no option for a house number or intersection. To give an example, I tried to get it to navigate to some friends who live near the centre of Torbay, a biggish UK conglomeration, their house has a name but no number. Having come from a background of using a free standing Garmin, which generally found 99.9% of any address you threw at it, in my opinion the performance of the Mazda system really sucks. My specific issues are that it struggles to find some addresses, particularly an address with just a house name and no number, and it really struggles to find rural address at all, even finding the centre of a village can be difficult. Having had my CX-3 for a bit over a year now, I wondered if any other owners have had issues with the satellite navigation?
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