bratt

"The Dodge Magnum R/T boasts technology that shuts down four of the Hemi's eight cylinders when the car is just cruising, delivering up to 30 miles per gallon during those moments." (http://www.automobile.com/2007-dodge-magnum.html)

I was wondering if the Corvette will ever be able to do this?
Maybe new computer modification upgrade?

DSteck

GM already has a Gen IV small black capable of displacement on demand... It's the L99. Whether or not GM will put one in a Corvette, who knows, but the automatic Camaros use them.

CPhelps

GM has had this ever since the LS4 in the 2006 W body cars (Impala, Monte Carlo, Grand Prix), and in the L99 as DSteck mentioned. Somewhere along the line GM changed their name from DoD (displacement on demand) to AFM (active fuel management), to further the confusion.

IIRC there was some issue with getting the system to work well with out the torque converter of an automatic transmission to soften the transition from 8 to 4 cylinders, which is why the L99 in the automatic Camaro SS has it, but the manual Camaro SS has the LS3.

WhiteDiamond

I think the biggest issue for the Vette getting such a system is the exhaust problem. On freer flowing exhaust systems, there is a very noticable change in tone when the system switches to 4 cyclinder mode. Ask any of the Dodge Hemi guys who swapped exhuasts on a truck or car with this system. Since the truck and cars can support a larger exhaust system(DoD cars seem to have three chambers, cats/main muffler/resonator), we will continue to see the system on those vehicles. The current Corvette layout makes such an exhuast very difficult and it would definately be heavier that the current exhaust.

I Bin Therbefor

Excessive vibration caused in the 6M trans cars. Works O.K. for the 6A.

Note in Camaro, only used in the A not the M.

Z0SEX

There are numerous occasions when I get around 30mpg in my M6 Z06...I think technology like that has no reason to be in a "Sports" car; I don't know too many corvette owners that are worried about the MPG when looking purchase one.

Dudeiwin86

it doesnt belong.

i drive a 2006 dodge charger (shopping for a daily driver so i can put my charger back to stock and trade in on a vette).

its a 5.7L and came factory with "MDS" aka multiple displacement system.... i could get up to 28 or 32 mpg easily on the highway... but its really irritatting.
if you have aftermarket exhaust... when it kicks down to 4 cyl mode.. most of them drone like a hona Civic fart can.

with heads/cam i disabled MDS completely and never would turn it back on until i trade it in bone stock.

the only reason they really did it tho is so they can have a higehr horsepower/emissions tuning and still get away with passing regulation MPG figures.

the new hemis coming out (6.4L) in 2012 will have this as well i hear.

Kevin93

I have a Jeep Grand Cherokee with the 340-hp Hemi and DoD and there are two things I've noticed
1) It is very non-invasive - I can't even tell when it's running on four
2) The mpg is still dismal, even on the highway (low teens), to the point I can't imagine how much worse it could be.

On a Vette though, the much lower Cd and taller gearing would probably make it more beneficial.

mike100

not mentioned yet...

more aggressive camshaft profiles conflict with DoD schemes that disable hydraulic flow to the lifters to shut down cylinders. big cams will wreck DoD lifters and or can't be used with higher spring pressures/rpms most likely.

CPhelps

Very true, and one of the reasons the L99 in the automatic Camaro SS has ~400 hp instead of the ~430 that the LS3 does in both Camaro and Corvette trim.

97Black

"i could get up to 28 or 32 mpg easily on the highway... but its really irritatting."

I also have an '06 Charger with the 5.7L but get nowhere near your 28-32 mpg. I usually drive 70 on the highway and average about 24 mpg on extended driving. Around town gets me around 17.

Michrider

I have a new Camaro SS, LS3 6 spd manual version. Absolutely love it.
I drove an L99 version, Auto with AFM 4 cyl mode. Absolutely hated it.

In the Camaro enthusiasts websites one of the biggest complaints is the stupid 4 cyl mode in the L99, and how to disable it thru tuning.

You might pick up a slight fraction of an mpg improvement, but it kills any joy of driving the car. If Corvette ever gets that horrid feature, it will not be purchased with my money.

brentil

As GM evolves the technology we will probably see a tech like this in a future Corvette if they continue the pure V8 route.

Dudeiwin86

the thing about it is,
its one of the only ways to be able to get a big-inch engine and still pass the Emmissions laws.

Chrysler is working on the new 6.4L hemi (to replace the 6.1L currently in SRT8 vehicles)

it will supposed have MDS (mulitple displacement system... aka DoD) as well as VCT (variable cam timing)

the new 5.7 in the R/T chrysler vehicles has VCT in them since 2009, which is how they make their extra horsepower over the 08 and earlier 5.7L vehicles.

these two tricks combined allow Chrysler to get passed emmissions standards on their bigger cube motors.

i think we will see a LOT more of this across all platforms and makes just so that we are still able to have our small (big cubic inch) block v8's we have now.

--

that wont stop the aftermarket from developing replacement lifters, and tunes to disable the system so we can go big on the cam.

and further more, as was mentioned, the transition from MDS 4-cyl mode, over to 8-cyl mode takes THOUSANDTHS of a second, there is not NOTICABLE performance loss.

with stock exhaust you cannot hear the transition...
the #1 reason people complain about the chyrler system is because they go and put aftermarket exhaust on their car, and now 4 cylinder mode sounds like.... just that... a 4 cylinder vehicle.

the drone on the highway in MDS Mode is insanely bad with aftermarket exhaust on the car, since they dont have the factory resonance cancellation for the 4 cyl modes.

however, the performance is still there. and there is no hesitation with the transition.

--

furthermore.
we stroked my buddies 5.7 (345 c.u) engine out to a 392 c.u.
we then took out his 2006 "mds lifters" and replaced them with 2009 MDS lifters
(the 2009 lifters accommodate more lift)
now his 450RWHP stroker motor has MDS on it working flawlessly.

he disables it most of the time, but enables it when he goes for long drives.

it has its quirks, but its not all bad.
as long as i can get rid of it if i want to, at least it will keep the big inch motors coming from the factory.