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SKYACTIV-X: first commercial gasoline engine to use compression ignition

www2.mazda.com

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Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#121

Post by ComputerGuru »

fnj wrote: post #110
cromulent wrote: post #63

Earlier quoted context omitted.

It's good work, but I suspect Mahle's TJI (as used in current F1 cars) is a better bet. - Fuel efficiency gains over 17% - over 40% thermal efficiency - over 99% reduction in NOx - significant reduction in CO2 http://www.f1technical.net/news/20316 http://www.mahle-powertrain.com/en/experience/mahle-jet-igni...

- over 40% thermal efficiency - significant reduction in CO2 CO2 production is directly inverse-linearly related to thermal eficiency. It is silly to list both.

This is far from a universally-realized/appreciated fact; it's good to list both for those that weren't aware.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#122

Post by btian »

elihu wrote: post #62

Maybe this is old news to people who pay attention to car news, but the most interesting thing to me is this line from the press release: > From 2019, start introducing electric vehicles and other electric drive technologies in regions that use a high ratio of clean energy for power generation or restrict certain vehicles to reduce air pollution I've been kind of disappointed that Mazda hasn't gotten into the electri…

Mazda is a small company. They don't have the kind of R&D budget to make EVs.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#124

Post by usrusr »

bsdetector wrote: post #30
ChuckMcM wrote: post #18

A reuters story on how it works: https://www.reuters.com/article/us-mazda-strategy-idUSKBN1AO... So this is 'gasoline' diesel. Or diesel without the NOx. Which, in theory, would give better fuel economy and possibly better torque. And it will ship in cars in the 2019 model year (so possibly as early as late next year). To me, it sounds like a "Don't pass"[1] bet on electric cars. Which they also are working with Toyo…

Or a bet on hybrids. Hybrids enable new types of engines that for instance operate at constant rate or that are under-powered for acceleration from a stop or going uphill.

From what I read about HCCI engines (the brand-neutral name for the general engine concept: https://en.wikipedia.org/wiki/Homogeneous_charge_compression... ) I suspect that they are not easily operated over a power band as wide as conventional gasoline or diesel engines. If that is the tradeoff, they could be a perfect match for hybrids.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#125

Post by sliverstorm »

maxxxxx wrote: post #85
Animats wrote: post #57

Earlier quoted context omitted.

Wankel engines work fairly well, but the geometry is so constraining that they can't be improved much. Can't change the shape of the cylinder head. Can't change the valve timing dynamically. That's all fixed by the geometry. They got as good as they were going to get decades ago.

Wankels are cool but they really don't have an advantage over regular engines other than vibrating less as far I know. And they have a few distinct disadvantages.

Better power curves & higher RPM capability, so you can use a smaller, more underpowered engine for the same application.

But that never overcame their mediocre gas mileage (lack of compression/poor combustion chamber shape), oil burning (oil-lubricated apex seals), and need for frequent rebuilds.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#126

Post by paulirwin »

mohaine wrote: post #89
mbreese wrote: post #38

Earlier quoted context omitted.

> I also wonder if the maintainability of these engines will be the same as with diesel They also include traditional spark plugs and the engine automatically switches between modes. So, I fear that maintenance wise, it may be the worst of both worlds -- but with less wear and tear on the spark side, perhaps it will be better.

I'm pretty sure "wear on the spark side" is an all but solved problem at this point. Most car engines made in the last 15 years have 100k mile lifetime on the entire spark system.

I know for more recent vehicles that is probably true, but as an owner of a 2006 F-150 with the 5.4L 3V Triton V8 that had the infamous spark plug issue, I had to lol with a tinge of sadness at your "last 15 years" comment.

Backstory: Ford came out the gate with a new spark plug design for the 2004 F-150 3V Triton 5.4L V8 engine (after their previous spark plug design failure in the 2V Triton where the plugs would shoot out) and told everyone that the spark plugs would last 100k miles. Turns out if you let them go that long, they would get stuck in the cylinder head and break off when you tried to remove them, leaving stuck broken pieces of spark plug behind. Conveniently, 100k miles happens to be when most people's warranty expires, leaving people with a best case a few-hundred-dollars-extra tune-up bill, if not thousands of dollars if the heads had to be removed. Ford faced a class-action lawsuit over this debacle, and there are still companies selling special broken spark plug removal kits designed solely for this engine to this day. Of course the root cause of the problem is faulty design, but it would have been mostly avoided had they not claimed a 100k mile service interval for the plugs. So yes, Ford went from an engine where the spark plugs would shoot out of the cylinder head, to one where they would get stuck so hard they would break.

I know all of this not because I am an engine geek, but because it happened to me. Two spark plugs broke off while being removed and I came this close to needing to have the heads removed and machined. Fortunately those special removal kits I mentioned earlier really do work. Given how relatively cheap spark plugs are, you can bet it will be a while before I trust that 100k mile number :-)

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#127

Post by mywittyname »

Danihan wrote: post #3

>Compression ignition and a supercharger fitted to improve fuel economy together deliver unprecedented engine response and increase torque 10-30 percent over the current SKYACTIV-G gasoline engine.*3 Wow. I already have a 2016 Mazda 3 that gets around 40MPG (even though it's not a hybrid) and it's already pretty peppy. Probably the best car I've owned, and I've owned several nice sports sedans. Getting 40MPG is too c…

> Blows any hybrid out of the water for total COO.

Not so sure about this. I have a 2014 3i GT and my wife has a 2014 Prius. Hers was cheaper to buy, gets way better mileage (29 v. 44) and needs less frequent oil changes (which are free), and is worth about $1200 more now.

It's a little faster, nicer inside, and much more fun to drive. But cheaper, nah.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#128

Post by IgorPartola »

linksnapzz wrote: post #34
ynniv wrote: post #27

Earlier quoted context omitted.

... as long as it isn't directly connected to the wheels? The rotational inertia would make for a very uncomfortable drive.

Chrysler made several generations of turbine cars in the '60s. http://www.allpar.com/mopar/turbine.html It was not, in the end, a production car, but there was a lot of data gathered as to performance and reliability in real-world settings. Not too long ago, Jaguar had a concept CX-75, which was a hybrid mid-engined supercar where the piston engine was replaced with two Bladon Jets micro gas turbines. After 2008, the…

Damn. That sounds like they almost made it work. I wonder how those cars would have done with corn ethanol. Electric boost for initial acceleration and better heat exchangers would have probably completely eliminated the remaining problems with them. Thanks for the link!

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#129

Post by busterarm »

flamedoge wrote: post #73
busterarm wrote: post #51

Earlier quoted context omitted.

> The fix was to have it towed to the dealer where they'd clean out the engine for a few hundred dollars. Later I learned you could tow-start it if you could get it up past 20mph. It'd put all kinds of foul smoke out the back when you did that but in terms of hassle, it was much better. You don't need to do all that. You can just pull the EGI INJ & EGI COMP fuse, crank it for a few seconds, replace and start it up. M…

They could've literally put this as a workaround

Mazda sort of assumed their drivers would read the manual and drive the car properly. I think this workaround was figured out at some point in the 90s anyway.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#130

Post by busterarm »

mikestew wrote: post #116
TomMarius wrote: post #74

Earlier quoted context omitted.

I though you Americans have it pretty rough when you're caught going over speed limit?

It very much depends on where in the U. S. one is at. East of the Mississippi River (eastern U. S.): I'm a good boy who doesn't do more than 10mph over the limit. The exception is Ohio: if I can't avoid the state completely, I do THE SPEED LIMIT. Western U. S.: whatever I think I can get away with. IOW, if I can see for multiple miles with few cross roads and driveways, then it's whatever I feel comfortable with. Tho…

Lol, I bought my RX-7 from an Ohio state trooper, in Ohio, and we raced the entire 2.5hr trip out of the state, in the rain. I think he called his buddies to leave us alone.
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