Compression Gasoline Engine?

[Tom K.]

http://www.autoguide.com/auto-news/...azda-skyactiv-engine-is-just-weeks-away-.html

This COULD be fascinating, but we'll have to wait a while longer for details.

Maybe all the benefits of gas and diesel engines, including a 30% bump in fuel economy.....

 

[Philpug]

I just read about this on Vortex..it does seem interesting. It will be in the next gen 3 from what I read.

 

[Eleeski]

30% is a huge jump in economy. Diesel fuel has a higher energy density which accounts for a lot of the fuel economy they enjoy. I'm skeptical but hopeful as well. And Mazda did successfully field the rotary engine.

Eric

 

[jzmtl]

Sounds too good to be true to be honest, the Germans has been playing with DI engines for a long time and if this were that good they'd jumped on it consider how they are in love with complicated toys.

Another problem I see is the reason diesel engine has high torque and low redline is because of the long stroke necessary for the high compression ratio, if they make a gas engine in similar fashion it would have the same problem i.e. lower redline and HP.

But we'll see how it turns out, interesting development for sure.

 

[Tom K.]

^^^ All those potential pitfalls seem likely to me, too, but from what I read, this is ready to go, very soon, in Mazda's 3 Series.

 

[Philpug]

Mazda said they were bringing a diesel here...with this on the very near horizon..I am thinking it ain't happenin'.

 

[oldschoolskier]

You can have high compression with short stroke engines too, mind you less torque, more RPM.

 

[Dave Marshak]

As a mechanical engineer, it seems really counter intuitive that gasoline compression ignition would work. Is it just a diesel cycle running gasoline? If it's an otto or sterling cycle, how do they control ignition timing? It makes me wonder why anyone would start working on such a thing. I never would have taken that job (not that they asked), and I've worked on some pretty far fetched things.

dm

 

[jzmtl]

As a mechanical engineer, it seems really counter intuitive that gasoline compression ignition would work. Is it just a diesel cycle running gasoline? If it's an otto or sterling cycle, how do they control ignition timing? It makes me wonder why anyone would start working on such a thing. I never would have taken that job (not that they asked), and I've worked on some pretty far fetched things.

dm

My understanding is squeeze first then inject gas, wasn't possible before direct injection since it would go bang before full compression. Although proper air fuel mix inside the cylinder seems difficult given it would ignite as soon as injection starts.

 

[Dave Marshak]

My understanding is squeeze first then inject gas, wasn't possible before direct injection since it would go bang before full compression.

That just sounds like a conventional diesel. Diesels are only about 5 or 10% more efficient than gas engines if measured correctly, so I don't understand how they expect to get a 30% improvement. Maybe the 30% number is bogus and they just are going for a dual fuel gas or diesel motor to address the problems of finding diesel fueling stations. OTOH after a long career I've learned never to say something is impossible when I don't fully understand it.

dm

 

[graham418]

As they say. .Timing is Everything. maybe by delaying the injection until almost the end of the squish? And maybe not as much gas is injected, thereby getting the increased efficiency?
It all sounds very interesting

 

[Tom K.]

A few more details:

http://www.autoguide.com/auto-news/...new-compression-ignition-skyactiv-engine.html

Super-lean burn, supercharged, gasoline, compression ignition engine, coming in at least one 2019 model.

 

[Snowfan]

3 cheers for Mazda. Zoom Zoom Zoom. If you've never driven an RX 7 or 8 you should. Rotary engines are awesome. Gotta give it to a company that is so involved with development outside the box. Then there is Mazda's steering feel....and the Miata. Great company doing great things. I hope the new engine succeeds. They would not have released the info if it was a dud.

 

[Tom K.]

Fairly in-depth article here:

http://www.autoguide.com/auto-news/...skyactiv-x-engine-tech-in-layman-s-terms.html

I won't be able to read it car-fully until later (ha, ha).

 

[jzmtl]

190 HP out of a economy car 2 liter, nice.

Efficiency improvement is only 13~14% though,

 

[DanoT]

190 HP out of a economy car 2 liter, nice.

Efficiency improvement is only 13~14% though,

Aren't the current generation of SkyActiv Mazda engines already very efficient, class leaders in fuel economy?

I would expect the 30% increase in fuel economy with the new compression gas engine occurs when compared to competitor's engines.

 

[jzmtl]

Aren't the current generation of SkyActiv Mazda engines already very efficient, class leaders in fuel economy?

I would expect the 30% increase in fuel economy with the new compression gas engine occurs when compared to competitor's engines.

I don't see it in real world figures, For example Fuelly shows CX5 has identical fuel consumption as Forester.

Regardless I'm happy to see Mazda being the forerunner in technology, they are essentially what Honda was in the 90's. Heck if they offered an engine upgrade in CX5 I'd probably be in one.

 

[Tom K.]

190 HP out of a economy car 2 liter, nice.

Efficiency improvement is only 13~14% though,

That was my first thought, too, but then I realized that these days, engines have already been highly designed and tuned for efficiency, so perhaps 15% is a home run.

 

[DanoT]

I don't see it in real world figures, For example Fuelly shows CX5 has identical fuel consumption as Forester.

Regardless I'm happy to see Mazda being the forerunner in technology, they are essentially what Honda was in the 90's. Heck if they offered an engine upgrade in CX5 I'd probably be in one.

What was so great about Honda in the 90's?, said the former owner of a '97 4Runner with a 3.4L 24 valve V6 and '86 16 valve Corolla GTS (rwd, baby!) and current owner since 2000 of a '93 MR2 (16valve turbo, mid engine, rwd, baby!)

Edit: I forgot about my '88 Toyota Celica All-Trac AWD turbo hatchback.

 

[jzmtl]

What was so great about Honda in the 90's?, said the former owner of a '97 4Runner with a 3.4L 24 valve V6 and '86 16 valve Corolla GTS (rwd, baby!) and current owner since 2000 of a '93 MR2 (16valve turbo, mid engine, rwd, baby!)

Non-expensive and fun to drive cars, willingness to try new stuff.