Mazda's Skyactiv-D (diesel) technology

[WesternStarSCR]

Mazda6 Skyactiv-D racecar gets first win at Road Atlanta


I am a new found fan of Mazda, and seeing what they are doing with ICEs without hybridizing. I am very technically curious.

I love the fact that they are using a non-SCR engine. I heard even the Cruze diesel will have to use DEF urea.

Getting around the cold start of a 14:1 CR with a bit of EGR for heat, and high temp fast glow plugs.

This thing is going to race in Detroit on Grand Prix weekend. Maybe I will actually go after all these years.

[Allch Chcar]

Originally Posted by ksa8907

Sounds to me like they are building a diesel with an engine they already produce but can't handle high compression. Sounds like a cheap shortcut.

The lower compression emits less NOx and gets most of the fuel economy. It works.

[gone-ot]

Originally Posted by WesternStarSCR

Mazda6 Skyactiv-D racecar gets first win at Road Atlanta

I love the fact that they are using a non-SCR engine. I heard even the Cruze diesel will have to use DEF urea.

...somehow, "pee-in-the-tank juice" (urea) just does not sound (smell?) intreguing at all!

[WesternStarSCR]

DEF works for what it is designed for in our Class 8 engines where I work.

But for cars, not having a DEF tank on the Mazda 6, and not having to have a regen cycle etc., this will help user acceptance. And the price of DEF over the counter at auto stores is insane.

+1 for Mazda

[Diesel_Dave]

Originally Posted by WesternStarSCR

But for cars, not having a DEF tank on the Mazda 6, and not having to have a regen cycle etc., this will help user acceptance.

It still has a DPF, so there will still be regen cycles.

And before we all hail Mazda as being so wonderful for not using SCR, remember that the same decision has nearly bankrupted Navistar in the heavy-duty world.

[WesternStarSCR]

I agree. Their whole engine business & future was riding on it though.

I am just glad about the Mazda engine being out there. Hopefully it will come with a 6 speed manual on the new 6.

[Occasionally6]

I think that the gas Sky-Active (sp?) engines also run compression ratios around 14:1. Oddly enough, I have seen several sources that suggest that is close to the optimum ratio for efficiency before the losses start to outweigh the gains with higher ratios.

I suspect that a lot of Mazda's thinking on ICE fuel efficiency has been worked through with the Wankel. They have done some interesting things with them. What comes to mind are the 6-port engines (the Wankel equivalent of variable valve timing) and shutting off the venturis for one of the rotors on decel. on some of the pollution controlled12a's.

Don't they also have an ultra-capacitor based KERS battery/alternator charge system?

[WesternStarSCR]

Yep, called "i-Eloop". Not standard on all models. And not available yet.

I think one of the biggest bummers is, once again, drum roll please, the EPA test procedure that does not take advantage of start stop tech.

Mazda has had "i-stop" for years in other markets, but Mazda and other non-hybrid models won't bring it to USA because it is no advantage on EPA sticker MPG number.

It is pretty cool how it restarts: it stops at an exact position where a timed injection and valve opening will ignite one then the remaining cylinders to her it running again.

[Diesel_Dave]

Originally Posted by WesternStarSCR

Yep, called "i-Eloop". Not standard on all models. And not available yet.

I think one of the biggest bummers is, once again, drum roll please, the EPA test procedure that does not take advantage of start stop tech.

Mazda has had "i-stop" for years in other markets, but Mazda and other non-hybrid models won't bring it to USA because it is no advantage on EPA sticker MPG number.

It is pretty cool how it restarts: it stops at an exact position where a timed injection and valve opening will ignite one then the remaining cylinders to her it running again.

I may be wrong, but I believe the EPA is making provisions for stop-start. I think the only issue is that if it's an option, the manufacturer will have to certify both ways--with and without stop-start. Just double the work to certify.

[euromodder]

Originally Posted by Diesel_Dave

I may be wrong, but I believe the EPA is making provisions for stop-start. I think the only issue is that if it's an option, the manufacturer will have to certify both ways--with and without stop-start. Just double the work to certify.

Many people shut off the autostart function though.

In the NEDC autostart is allowed, but in real life you'll never see the big gains it gets on NEDC - which has numerous phases at standstill.
These were introduced to simulate traffic: accelerate, brake, wait, ...