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Discussion Starter #1
This is from allpar, not new but just read it today and thought I'd share:

Chrysler announced on June 21, 2007: “For 2009, Chrysler Group [sic] will deliver a significantly upgraded version of its renowned 5.7-liter HEMI V-8, resulting in notable gains in fuel efficiency, refinement, power and torque.” They also announced that the Phoenix V6 would get MDS. The gains are expected to come via variable cam timing, according to always-accurate oh20.

Redriderbob had correctly predicted in May 2007: Chrysler will be debut a revamped Multi Displacement System (MDS) on most of its V6 and V8 lineup by the year 2010. They have been working on a new updated MDS system that will debut on the 2009 Dodge Ram 1500 models. After its debut, it will be featured on the full V8 lineup (except SRT). Most of the V6 engines in Chrysler’s arsenal will also feature MDS.

oh20 also said we can expect three 5.7 Hemis in 2009; the variable-cam edition should be around 380 hp. At the same time, a 6.4 liter Hemi is expected to get nearly 500 hp (we have heard a range from 450-480). He also said that the 6.1 Hemi (SRT version) might get MDS in 2009 or 2010.
 

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wait and see
things change alot in two years
 

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I believe GM has a V6 that features cylinder shutdown. I think Honda has this on their V6 as well.
 

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OK, now throw direct injection into the mix!!
 

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I thought the same thing. Running a V6 on 3 cylinders seems unbalanced; so I wondered if it would run on 2.
Honda has it in their Oddyssey minivan and it runs on 3 cylinders when in econo mode .... I read that the 2008 Accord has an updated version which cuts down to 4 or 3 depending on load :knockout:
 

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Honda has it in their Oddyssey minivan and it runs on 3 cylinders when in econo mode .... I read that the 2008 Accord has an updated version which cuts down to 4 or 3 depending on load :knockout:

How on earth do they manage the valves?
 

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How on earth do they manage the valves?
Don't have that answer but this is off Honda's website about how their system works:

"The Accord’s V-6 features the latest generation of Variable Cylinder Management™ (VCM®) technology. This system can activate and deactivate the engine’s cylinders as needed to meet the demands of both acceleration and fuel savings. When maximum torque is required, all six cylinders are firing. During steady cruising speeds , VCM shuts down one bank of cylinders. In this mode, the audio system’s Active Noise Cancellation™ (ANC) function generates out-of-phase sound waves to cancel out any undesirable noise that may be due to the harmonics of 3-cylinder operation. As cruising speed increases the engine moves to a 4-cylinder mode for extra cruising power. To help keep engine vibration from reaching the cabin in every mode, active engine mounts automatically adjust their firmness to help absorb energy. "
 

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In this mode, the audio system’s Active Noise Cancellation™ (ANC) function generates out-of-phase sound waves to cancel out any undesirable noise that may be due to the harmonics of 3-cylinder operation.
Bye bye MDS drone.

To help keep engine vibration from reaching the cabin in every mode, active engine mounts automatically adjust their firmness to help absorb energy. "
Bye bye MDS drone.
 

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I think I read that that new Pontiac can go either 8,6,4 or 3 cylinders depending on the need.
Its friggin such a smart idea.
 

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I think I read that that new Pontiac can go either 8,6,4 or 3 cylinders depending on the need.
Its friggin such a smart idea.
You didn't.



GM's cylinder deactivation cuts down the V8 to 4 and the V6 to 3 .... no steps anymore (remember the V8-6-4 ? )
 

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No they don't. They stay closed to keep an air pressure charge in the cylinder until it reactivates.

Doesn't the cam still turn??? Then how do the valves stay shut......
 

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Doesn't the cam still turn??? Then how do the valves stay shut......
The lifters are diconnected.

From Allpar.com's 5.7 Hemi info page: "The system deactivates the valve lifters. This keeps the valves in four cylinders closed, and there is no combustion. In addition to stopping combustion, energy is not lost by pumping air through these cylinders."
 

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Discussion Starter #20
Doesn't the cam still turn??? Then how do the valves stay shut......
On our cars, the hydraulic valve lifters bleed down, electronically controlled by oil flow.

Reminds me of Rhoads lifters. They are lifters to be used with big cams that bleed down some at low rpm, for better idle and low-end torque, and stay "pumped up" at higher rpm, for more power. Low-tech variable cam timing, in effect. http://www.rhoadslifters.com/
 
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