http://www.foxnews.com/auto/2017/01/16/mazda-reportedly-introducing-sparkless...

What does this mean?    Run 18 to one compression ratios, use any fuel, use direct injector tech to deliver the burnables to the hot compressed air at computer controlled (variable) VERY LEAN injected ratios.  

USING GASOLINE (alcohol blends) will keep emissions down vs diesel fuels so it is coming to the marketplace first as an emissions based imperative.

Several automakers and engineering outfits have been working on HCCI in recent years, but issues with cold starting and the precise timing of the combustion make it a difficult technology to engineer.

One solution has been the incorporation of part-time spark plugs that kick in at certain temperatures or engine loads. Mazda hasn’t publicly revealed its plans, or exactly how its version works.

..... duh, remember glow plugs?    Just use a glow plug and a richer mix temporarily to help you get the engine started and warmed up good.

A lot of blown head gaskets ! 20:1 compression means 2000psi cylinder pressure!If they use it on the rotary engine the seal on the tips of the rotors aren't going to last long either .

Kris01 wrote on 01/23/17 at 17:12:53:


Part of that is the shape of the combustion chamber....and the size.  As the flame front travels away from the spark plug, the temperature of the fuel/air mix increases ahead of the flame- and when it gets hot enough it will detonate if it is not all burned.  On the Mazda the flame travels a shorter distance than on the Chevy 350....and a fuel injected engine has a computer that can sense knock and make timing adjustments.  It is hard to believe that all this can happen 50 times a second!

Kris avgas is a joke! the octane in avgas is for planes with motors running 3000rpm at 5,000 ft ? A gal of avgas about 6lbs. a gal of reg gas about 8lbs their made from different chemical bases for two very different uses. If you believe that avgas is better than pump gas your fooling yourself.It's used in planes because it doesn't freeze and the air is thin ,giving the motor a rather slow burn rate ,thus the need for higher octane !Octane has nothing to due with power,but is in fact,only the measure of a fuel's resistance to detonation .While your friend with the vette doesn't have to worry about detonation ,he's not running "racing fuel".A good grade of pump gas should give better mileage and performance.

batman wrote on 01/23/17 at 21:48:24:

Kris avgas is a joke! the octane in avgas is for planes with motors running 3000rpm at 5,000 ft ? A gal of avgas about 6lbs. a gal of reg gas about 8lbs their made from different chemical bases for two very different uses. If you believe that avgas is better than pump gas your fooling yourself.It's used in planes because it doesn't freeze and the air is thin ,giving the motor a rather slow burn rate ,thus the need for higher octane !Octane has nothing to due with power,but is in fact,only the measure of a fuel's resistance to detonation .While your friend with the vette doesn't have to worry about detonation ,he's not running "racing fuel".A good grade of pump gas should give better mileage and performance.

Correct. Avgas is distilled for long life and constant throttle application. From an octane standpoint, 100LL is about the equivalent of 92-93 mogas.

Kris ,your friend  could advance his spark timing this would advance the flame front before the compression gets high enough to cause detonation..

http://www.autonews.com/article/20140106/OEM06/301069997/mazda-pins-improved-...

Mazda engineers aim to eke the gains by cranking up the engine's compression ratio to 18:1, from a current level of 14:1. Higher compression tends to improve fuel economy because they can achieve the same combustion temperature with a leaner mix of fuel. Mazda says the 14:1 ratio in its first-generation Skyactiv gasoline engine is the world's highest.

That system may help Mazda comply with 2025 emissions targets.

It would limit the fluctuation of heat in the combustion chamber to reduce losses from exhaust and cooling, Hitomi said. That would make more energy available for powering the wheels.

This is shooting for the 30% EPA improvement requirements for 2025

...... as if Trump is going to let the future stupid EPA rules stand, choking down his "Make America Great" to a halt.   However, it is a readily doable tech that has all the parts already in widespread use in the car industry.   And even if they are mebbe initially failing to hit the 2025 targets right off the bat the trick still yields something quite tasty for meeting the 2020 EPA requirements.

Downsides is that the trick doesn't work at high RPM or very low RPM or a rapidly, constantly shifting RPM --- look to see it mated with CVT transmissions that are computer controlled to run at the RPM sweet spots and look to see that most all the car speed changes are done at a constant "sweet spot" RPM by computer controlled wide range CVT transmissions.

Note:  my Cube does this already, it naturally seeks 1200 rpm, 2000 rpm and 3600 rpm for making and controlling engine HP and it uses the CVT for the speed shifts up and down.  

This is existing tech, well understood.

The new Mazda will not be a sports car, it will be a mileage car, a daily driver with so-so acceleration, but unlike today's battery vehicles it will have endless range and rapid refueling (same as we enjoy today) and it will fall into normal car price ranges.

By striking first with both announcements and patents, Mazda hopes to get royalties from all car makers that go this route in the next 7 years or so .....

Thanks OF! That all makes sense. My car gets nearly the same mpg as the bike. Always a plus!