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"School of Hard Knocks" - Story on GM's HCCI
http://www.caranddriver.com


After more than a century leading separate lives, Rudolph Diesel and Nikolaus Otto are finally getting a place together. General Motors’ experimental 2.2-liter homogenous charge compression ignition (HCCI) engine can shift from spark ignition to diesel mode faster than you can say “außerordentlich!”

The goal: stretch fuel economy from an existing engine design by up to 15 percent by adding just a few bits of hardware and some software code.

Able to burn either gasoline, ethanol, or E85, the HCCI design utilizes direct injection and variable valve-timing hardware to switch from spark ignition during acceleration and high speed to compression ignition during idle and light-throttle cruising.

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Not only old news, but also somewhat misleading explanation of HCCI. HCCI is not quite the same as how a diesel operates. You can actually run diesels in HCCI mode also. Diesel start the ignition process by injecting fuel when the air in the cylinder is at a pressure and tempurature already well beyond what is needed to burn the fuel. HCCI compresses an air/fuel mixture until it eventually ignites. This makes them quite different since with a traditional diesel you still have direct control of the ignition through fuel metering. With a true HCCI engine you kinda have to alway be running perfect presures and tempuratures to control ignition, so there is really no direct control of ignition outside of messing with EGR gasses into the cylinder and such to retain the right temperature and pressure and such.
 

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Old news. And this doesn't give us any new info. Sorry bro. Do we have any idea when it might be on its way?
very true. :)
 

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Old news. And this doesn't give us any new info. Sorry bro. Do we have any idea when it might be on its way?
How 'bout on the Volt? Sounds like a perfect application for it.
We can only hope they will stick this one in there unannounced...
 

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How 'bout on the Volt? Sounds like a perfect application for it.
We can only hope they will stick this one in there unannounced...

That wouldn't really make sense. The engine in the Volt doesn't drive the wheels. Since it only charges the battery, it just needs to be a small generator engine, mostly running at a constant, optimized RPM in an on/off fashion. Giving it multiple modes of operation would be expensive and pointless.
 

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That wouldn't really make sense. The engine in the Volt doesn't drive the wheels. Since it only charges the battery, it just needs to be a small generator engine, mostly running at a constant, optimized RPM in an on/off fashion. Giving it multiple modes of operation would be expensive and pointless.
"up to 15 percent by adding just a few bits of hardware and some software code."

That doesn't sound expensive. And it would be a great application on the volt because the Volt is all about using as little fuel as possible. Making it even more efficient, and more advanced would make it more marketable.
 

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The projected efficiency gains come from the engine having multiple modes of operation and being able to select the most efficient mode for a varying situation.

Able to burn either gasoline, ethanol, or E85, the HCCI design utilizes direct injection and variable valve-timing hardware to switch from spark ignition during acceleration and high speed to compression ignition during idle and light-throttle cruising.
With the Volt, there's no need to design an engine to accommodate both high RPM acceleration and low RPM cruising because it isn't connected to the wheels. It can just run at the speed that offers the best power/fuel ratio to recharge the battery then turn off when it's no longer needed rather than spooling up and down. If it's running at a constant speed, it won't need multiple modes of operation.

You have to keep in ming that it's a generator, not an automobile "engine" in the traditional sense, so technology that improves efficiency in normal automive applications won't necessarily translate to efficiency improvements in the Volt. It just wouldn't benefit from HCCI or VVT or similar technology.
 

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"up to 15 percent by adding just a few bits of hardware and some software code."

That doesn't sound expensive. And it would be a great application on the volt because the Volt is all about using as little fuel as possible. Making it even more efficient, and more advanced would make it more marketable.
No.
Keep the mileage the same and use the efficiency to power a bigger generator (100 kilowatts) to produce more energy for the Volt to run.
 

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Where's Saabr to fill us in on the prototype Saab variable compression ratio engine? I guess it was a head gasket nightmare
 

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Old news. And this doesn't give us any new info. Sorry bro. Do we have any idea when it might be on its way?
I am personally convinced it is going to come on the Cruze. How else can a compact to mid-size car is gong to deliver 40+ mpg with a gas engine?

Of course, this would mark a huge change of MO for GM. They always hype any new thing for several years before putting it on the market, thus ensuring that no one's interested by the time they can actually buy.

In so doing they wind up getting nice publicity for the company, but it's all been spent by the time it could be good publicity for an actual sale. I advocate they just clamp down, spend a couple years not worrying about the image of the company, then spring a bunch of great products on us, products whose sales will be driven by excitement about their merits. Wacky, huh?
 

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Either way, the volt could use it.
No. It would be a waste of money in the Volt. If the HCCI can run (sort of) as a gas engine (for acceleration/ high speed) or a Diesel (for cruising/ fuel economy mode), why would you pay for such a thing that NEVER would use the gas engine mode? The Volt's electric motor handles the acceleration AND cruising modes, the gas engine only charges the battery at a steady state "cruise" mode no matter what the car is doing. A Diesel would fit that bill at maximum efficiency. Why add the "few bits of hardware and some software" for no gain?
 

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No. It would be a waste of money in the Volt. If the HCCI can run (sort of) as a gas engine (for acceleration/ high speed) or a Diesel (for cruising/ fuel economy mode), why would you pay for such a thing that NEVER would use the gas engine mode? The Volt's electric motor handles the acceleration AND cruising modes, the gas engine only charges the battery at a steady state "cruise" mode no matter what the car is doing. A Diesel would fit that bill at maximum efficiency. Why add the "few bits of hardware and some software" for no gain?
That's exactly why the Volt could use it. The design problem with HCCI in cars is that accelerating puts strain on HCCI so it has to cut out.

The 1.6 litter four in the Volt now probably will only run at 1200-1500 RPM, HCCI is more efficient so its an obvious choice once costs get down.
 
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