[RSnyder]

Scientific American (Dec. 2004) has a "news scan" short article on cylinder-shutdown technology. Although it's been tried before without much market success, DiamlerChrysler and GM are claiming it will succeed this time because electronicly controlled throttles allow them to keep the transition between 8 and 4 cylinders much smoother. There wasn't much of a description of the engineering other than to say they deactivate valves by using oil pressure to collapse special telescoping lifters.

The article concludes with a Chrysler development team leader quoted as claiming they will outsell hybrid electric vehicles within a year or two and thus, by sheer numbers, be responsible for more total gasoline conservation.

 

[ehurtley]

I believe it. Simply because of supply issues. Unless Toyota and Honda can ramp up hybrid production a lot more than they currently have planned, it's obvious. It is a much simpler process to create a cylinder-deactivating car than to create a hybrid.

In the long term, once hybrid supply issues are resolved, I think Hybrids will become a large percentage of the market. However, as long as gasoline-powered cars are a large part of the car market, I don't think ALL gas-powered will become hybrids. (High-efficiency diesels are very similar to hybrids from most environmental standpoints, but they are far worse than normal gas cars in the few places that they are bad in.)

As has been said elsewhere, much greater environmental impact would be had by converting heavy fleet vehicles such as busses and trucks, than by converting passenger cars, to hybrid. But that doesn't mean we should ONLY concentrate on those. I will be looking forward to replacing my Ford Explorer with a hybrid SUV next, then hopefully replace my cheap beater car with a low-end Hyundai or Kia hybrid that comes in under $10,000. (Hey, Hyundai has said they're trying to do just that.)

 

[ElectricTroy]

"Chrysler claims cylinder deactivation will outsell hybrids."


Not if the hybrids include cylinder deactivation too (Accord Hybrid).

 

[ehurtley]

Heh. Of course, one could consider ALL hybrids as 'cylinder deactivation' vehicles. After all, I'm cruising along at 30 mph, and my Prius deactivates ALL of it's cylinders.

 

[ElectricTroy]

Actually I was talking about the Accord's ability to cruise on only 3 cylinders

 

[ehurtley]

Can't tell a joke?

Actually I was talking about the Accord's ability to cruise on only 3 cylinders

Yeah, I know, I was just being funny.

 

[SkipHuffman]

Prius shuts down cylinders too. (And not just all four)

 

[ElectricTroy]

You mean when coasting to a stop?

 

[RSnyder]

"Chrysler claims cylinder deactivation will outsell hybrids."


Not if the hybrids include cylinder deactivation too (Accord Hybrid).

Actually, the more hybrids include cylinder deactivation, the more likely that cylinder deactivation will outsell hybrids (assuming at least some non-hybrids include cylinder deactivation).

 

[RSnyder]

Prius shuts down cylinders too. (And not just all four)

Any chance you could elaborate on this?

 

[SkipHuffman]

Prius shuts down cylinders too. (And not just all four)

Any chance you could elaborate on this?

It is in the manual somewhere. I will have to look at it tonight.

 

[ElectricTroy]

I've never heard of that. The Prius is a small engine, and it needs all 4 cylinders to keep moving down the road (ditto the Insight/Civic). It can't turn them off, else it would lack enough power to push through the air.


The Accord is a large 6 cylinder engine, so it can shut off 3, and still have enough power to cruise.

 

[SkipHuffman]

Prius shuts down cylinders too. (And not just all four)

Any chance you could elaborate on this?

It is in the manual somewhere. I will have to look at it tonight.

Perhaps I was mistaken. It woudnt be the first time. I cannot find it in the manual.

 

[BIF]

I was going to make a tongue-in-cheek comment about Toyota vs. "the other guys" in terms of reliability and cylinder-shutdown (IE - "Fix Or Repair Daily" or "General Maintenance"), but then I realized there was actually a serious point to be made here.

Yeah, guys...the Prius does shut down cylinders, but not in the same way as GM and DC will.

First, and most obvious, the engine shuts off at traffic lights and when running in EV/Stealth mode. That's cylinder deactivation in an "all-or-nothing" manner.

Second, and less obvious: At highway speeds and at other times, the engine will shut down cylinders by preventing compression, fuel/air injection, combustion, and ignition. And the internal parts will continue to move. Some call this what..."warp stealth?" The engine moves, but though the pistons keep moving, there's no fire in the hole. So that is cylinder deactivation, right?


There's another thing, too...the whole use of the Atkinson-Miller combustion thingie. While it's not cylinder "deactivation," per se, it DOES represent a different way of thinking about the internal-combustion engine. Compared to Otto, Atkinson-Miller is almos like a "partial-reduction" in cylinder activation, because less fuel is present during the combustion phase.

I dunno, help me out one of you engineers!

 

[ElectricTroy]

In this case, "cylinder deactivation" refers to a car's ability to switch between a V-6 and an I-3... or a V-8 and a I-4... or a V-12 and a V-6. The car can change itself from large engine to small engine, and vice-versa, and still move down the highway.