My Mazda 3 Skyactiv (first gen) is 12:1 compression on regular gas. Gets great MPG, wonder what this can do. Basically Mazda says they’ll switch from regular gas when all the new tech has been shaken through the sieve of market acceptance. Until then they’ll ring everything they can get out of a gas engine. I think they also see a chance to perfect a small high efficient generator for a hybrid.
One thing to keep in mind about HCCI, which the sparkless gas engine uses. In a diesel engine, fuel is injected closed to the end of the compression stroke. Fuel ignites upon contact with hot, compressed oxygen. The flame grows as more fuel is injected. In a spark ignition engine, the should originate from the spark plug and the initial flame ignites the mixture around it by travelling. In both of those, the flame takes time to grow.
In a HCCI engine, the fuel and air is mixed at the intake just as port fuel injection. The mixture is then compressed until it gets hot enough. Since the entire mixture is subjected to the same pressure hence temperature, the mixture ignites at once. With this type of engine, the exact timing of ignition is not controlled by the spark but is predicted by varying the amount of compression. This requires much more computational work from engine control. It has to control the amount of compression under different condition to achieve ignition closed to the desired time.
No, that’s not right. Direct injection gasoline engines inject fuel at a precise time into the combustion chamber. All the mixing occurs in the combustion chamber, not in the intake manifold (except those engines with 2 injectors per cylinder, one in the intake and one in the combustion chamber) Usually multiple shots. In modern direct-injection diesels, the same occurs. The timing of that, and subsequent injections, is what defines the ignition timing of the combustion.
The new Toyota FRS/Subaru BRZ engine has both port and direct injection combined. It would seem to be a good solution to the carbon (on the intake valves) problem in other direct injection engines. I have to wonder if it has any real benefits. The mileage is rated at 21/28, not exactly a mindbender. BTW, I just visited the Toyota site, and I guess since obsoleting the Scion name they’re going to call it the “86” now.
Yup!
However, I have to question the…worldliness…of the folks who came up with that “86” name. The meaning of 86, as a slang term, implies that this model is going to be discontinued!
Interesting point. I guess we’ve all heard the term “86 it”, meaning trash it.
Perhaps the Japanese translation of “86” means “wonderful”?
Or perhaps someone just wasn’t thinking. 
I guess it is possible that Toyota corporate in Japan selected that “86” name for the US market, but I was under the impression that the Japanese car companies had long-ago decided to have US-based personnel select model names for the US market, European-based personnel to select model names for that market, Latin American-based personnel to select model names for their market…and so on…after some unfortunate model name choices years ago.
I’m drawing a blank right now on some of the other…embarrassing…silly…or just plain ridiculous…Japanese model names from the past, but the ones that definitely come to mind are the Nissan Cherry and the Nissan Fairlady.
No, it’s because the Toyota 86 (as it’s been called overseas since it’s introduction) is considered the spiritual successor to the AE86 Corolla/Sprinter, which is cult favorite in Japan and in the drifting scene. The current “86” is an homage to that car.
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I agree that’s there is a legitimate reason for the model name 86, but all I could think of when I first heard it was Agent 86, Maxwell Smart, and how they came up with his agent identity.
I’m still looking for someone to build a direct injection 2-stroke engine and it seems that Renault may do it. Power/weight greatly exceeds 4 stroke gasoline engines.
this link ran off the rails. Sorry, see below.
Speaking of bad car names, the Chevy Nova allegedly didn’t do well south of the border.
“Nova” means “no-go” or “it doesn’t go” in Spanish.
On second though try this link
Ah, okay. Got it.
Direct injection creates a stratified charge. Then it is either compression ignition or spark ignition. I think Hyundai toyed with SCCI. Mazda is talking about homogeneous charge, which is achieved by mixing fuel and air at intake
@FoDaddy is correct. Toyota loves its letter/number designations. Each body style has a designation. I used to have an 86 Tercel 4WD wagon. They were made from 83 to 88 and were designated AL25. Each engine also as a similar designation, my Tercel had a 3AC engine. The AE86 was the last of the rear wheel drive Corolla’s. It could be had with a 4AC engine (75hp) or the more desirable 4AGE (up to 160 hp)
Industry has gone way past the 2013 book you listed given the advances in direct injection. Industry is further ahead than academia. The book is trying to create classifications of the types of combustion that have been eclipsed by the technology. You don’t have to create a homogeneous charge to achieve combustion ignition in gas engine. If there is a localized area of 14.7:1 air/fuel ratio, that can be used to ignite a lean A/F area and complete combustion. That principle has been used in “lean burn” engines quite a while ago. It is further refined by being able to inject fuel directly in the combustion chamber at any point (or many points) in the stroke to achieve a reliable compression ignition in a gas engine at the correct time.
I remembered either you or one of the other posters mentioned the “2 injectors per cylinder” about Toyotas when we were discussing direct injection. I agree it would be a good carbon buildup fix.
I’ve seen and read about race car engines with 2 injectors spaced certain distance apart and timed to squirt at a particular resonance frequency. The added mass reinforces the air charge as it enters the cylinder for more torque or HP depending on when its injected. I don’t know if a street engine can benefit much from that with air filters and not so much wide open throttle. I see a Nissan article from about 2009 where they used 2 injectors sided-by-side so they could get better fuel control and smaller droplets for greater efficiency.
I’m glad that you used the word, “allegedly”, because that fable was debunked, long ago:
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Very interesting to have such dynamic control.
Is this essentially a newfangled way of taking advantage of pulse charging?
Or are you describing something else?
It might have been me, I mentioned that the new Toyota/Subaru engine in the FRS/BRZ uses both port and direct injection combined. I read all the alleged technical benefits, but cannot recall the details. I try to be careful with this type of information because the technical benefits are always highlighted, but any weaknesses never are until they begin to affect the public at large. Just as direct injection resulted in carbon buildup, this system might have a hidden demon too.
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