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Old 10-24-2017, 06:28 PM   #21 (permalink)
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Originally Posted by niky View Post
This was the same problem with Mazda's iStop. The EPA city cycle doesn't show its effects, even though real world testing has shown a 0.5 to 1 km/l difference in 8 km/l traffic.

We have to wait to see what Mazda does. I am assuming that it uses HCCI over a wider cycle than GM's older system precisely because it uses spark-controlled compression ignition.
EPA 5-cycle testing goes all the way up to 85 mph (US06 cycle). The 5-cycle test is used for the window sticker. The 2-cycle test (FTP75+HwFET) is used for GHG and CAFE compliance and the highest speed on the HwFET is 65 mph as stated. 5-cycle test results are much closer to real-world averages. Also, iStop would get GHG credit from EPA through their off-cycle credit program - so if the Mazda chooses iStop in the U.S., they can put it on the vehicle and take the credit towards their GHG compliance. If it isn't offered, it may be for consumer acceptance reasons or it could be that they just don't need it to meet the current standards.

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Old 10-24-2017, 06:31 PM   #22 (permalink)
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The one issue is that you require a deep cycle battery, which costs... well... not an arm and a leg, but a few fingers and toes, at least.

Friend uses a regular battery in his car.

He simply wedges the iStop button down with a piece of folded paper. No iStop, no need for deep cycle.
Any of the vehicles switching over to 48V electrical systems between 2018 and 2022 will be doing so in part to better enable idle-stop systems. This is showing up in expensive vehicles first (Mercedes), but once economies of scale kick in with additional offerings among EU market vehicles, we should start to see more 48V systems on vehicles in the U.S. It's a no-brainer for luxury cars - their 12V electrical systems are already overtaxed with the content that is going into higher end vehicles these days.
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Old 10-24-2017, 06:34 PM   #23 (permalink)
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Always beware of the term 'up to'.

It's a 30% gain only in the narrow band that HCCI will operate in. So owners won't be seeing 30% reductions at the pump. It's a bit like lean burn or cylinder deactivation.
It actually is exactly lean burn. The only reason they are doing a spark-assisted variant of HCCI is to allow leaner operation. It will be interesting to see what they have to do for NOx emissions control to meet the Tier 3 emissions standards in the U.S. - that is a real challenge for any lean strategy, whether it is some sort of gasoline HCCI concept or diesel.
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Old 11-08-2017, 09:39 AM   #24 (permalink)
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I've got to do an infographic on that system soon. It's uttelry fantastic.

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Any of the vehicles switching over to 48V electrical systems between 2018 and 2022 will be doing so in part to better enable idle-stop systems. This is showing up in expensive vehicles first (Mercedes), but once economies of scale kick in with additional offerings among EU market vehicles, we should start to see more 48V systems on vehicles in the U.S. It's a no-brainer for luxury cars - their 12V electrical systems are already overtaxed with the content that is going into higher end vehicles these days.
The way some of these cars drain their batteries when parked is unacceptable. That change can't come soon enough.
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Old 11-08-2017, 10:54 AM   #25 (permalink)
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All that "content" leaves me cold. Not impressed.

Make mine a modern Model T with about that level of amenities.

Guess I'll have to make my own.
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Old 11-08-2017, 10:59 AM   #26 (permalink)
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I drove a Russkie truck that might suit you. The UAZ Hunter (military Jeep)

Sliding windows. Good old dip switches for the fuel tank switchover, headlamps and running lights. No radio. Simple AC system. Only electronics are the engine management systems.

Built to go way, way off-road. Dual live axles, near-vertical approach angle. Cloth roof. Diesel economy. As a bonus, rides a bit better on road than a Wrangler, to boot.
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Old 11-08-2017, 11:57 AM   #27 (permalink)
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Originally Posted by joemac View Post
It actually is exactly lean burn. The only reason they are doing a spark-assisted variant of HCCI is to allow leaner operation. It will be interesting to see what they have to do for NOx emissions control to meet the Tier 3 emissions standards in the U.S. - that is a real challenge for any lean strategy, whether it is some sort of gasoline HCCI concept or diesel.
How lean, exactly, I wonder? Honda's lean burn motors run well at 22.5-24.0:1.

Are they going to need exotic emission controls?
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Old 11-08-2017, 03:29 PM   #28 (permalink)
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All that "content" leaves me cold. Not impressed.

Make mine a modern Model T with about that level of amenities.

Guess I'll have to make my own.
Yep, the "first" *S* in the K.I.S.S. principle, "simple."
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Old 11-08-2017, 03:33 PM   #29 (permalink)
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Quote:
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I drove a Russkie truck that might suit you. The UAZ Hunter (military Jeep)

Sliding windows. Good old dip switches for the fuel tank switchover, headlamps and running lights. No radio. Simple AC system. Only electronics are the engine management systems.

Built to go way, way off-road. Dual live axles, near-vertical approach angle. Cloth roof. Diesel economy. As a bonus, rides a bit better on road than a Wrangler, to boot.
My gutted '60 Kombi is darn close, but a bit large for a DD.
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Old 11-08-2017, 10:29 PM   #30 (permalink)
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How lean, exactly, I wonder? Honda's lean burn motors run well at 22.5-24.0:1.

Are they going to need exotic emission controls?
The toughest standard is something like 0.02g/mile NOx (need to check on that again), which works out to something in the tens of ppm depending on how much fuel you burn in a mile.

I think if you drop the combustion temperature by a little bit it is easy to go below 100ppm (which should be able to squeak by the minimum standards on a smaller engine car). HCCI supposedly should be able to control the burn speed so that maximum temperature is lower.

I am not sure exactly how this works, but my hunch is that they use a lot of hot EGR to control the charge temperature (to induce autoignition) and reduce the burn temperature, and somehow avoid knock.


Last edited by serialk11r; 11-08-2017 at 10:46 PM..
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