8 to 4 cyl will it be on ls2

[highlander_69r]

i saw the ad on tv for some 4wheel drive with the hemi v8 , that for the point of my thread can run on 4 cyl when required to "save fuel".i remember an article ages ago about the ls2 in america having the same technology and with the ve due soon weather holden or hsv will employ this technology to seem more fuel efficient to the public, considering oil will only be goin up for a while

[ecka]

If it's in the states, no doubt we'll eventually get it here. Good pick up.

I've said it on the fuel price thread though, whilst we've all got to be mindful of the family budget, and the house and kids come first - there does come a point when you've gotta say "it's a V8 for chrisssssakes!" Because if the market want to get real pedantic, why drive a 2.0 litre 4 cyl? Why not the 1.3's etc? Because the real small ones SUCK, that's the answer. Fuel economy be damned. On the same token, why drive a 6 cyl around town if it's not for the space to pack people and gear into?

At the end of the day a V8 is for pleasure. Like the old saying goes, you can't have your cake and eat it too.

[VTSS350]

Its called DOD or displacement on demand. It will exentually come our way

[Ghosn]

We wont need to drop a few cylinders to save fuel, moreso to let the Fords keep up :P

[OzJavelin]

Early on there was talk of DOD being built into the LS2, but GM dropped it for some reason. They used to have it years ago in the "infamous" Caddy V8 (4.1L I think?) .. it was terrible, but that was early days. What Mopar are doing with the Hemi is the modern incarnation of this. I think it's basically shutting down cylinders by control of the injectors and lifters. However the system does not shut them down completely; it reactivates cylinders periodically to keep them "healthy". This - and the fact of the additional drag of the "dead cylinders" - is why they don't get a 50% fuel decrease .. more like 20% at most. But these things were basically introduced to keep big V8s in American SUVs, so any saving would be welcome.

GM and Ford will have to introduce their own systems soon, but they are probably smart to wait and see how the Mopar system goes .. both techncially and acceptance by the public?

[VYBerlinaV8]

Does anyone have any figures on how much DOD reduces fuel consumption in real world driving. I agree it's a great idea, but if we have to put up with addded cost, complexity, weight and maintenance for a 5% saving, I don't think it will get up.

[Jac001]

I seem to have read that Mercedes have a V12 that has DoD which shuts down one bank of cyclinders and becomes a Straight 6. In the real world the feul economy is meant to be around the same as there V8 model, but i can't remember the exact conditons or find a link right now on it...

from
http://www.thecarconnection.com/Industry/Techno_Beat/Finding_the_V-8s_Smarter_Half.S198.A3826.html


"While you'll have to wait a bit for GM's cylinder-deactivation technology, those who can buy a Mercedes vehicle equipped with their new twelve-cylinder engine can have it now. Called "Active Cylinder Control" (ACC) it does essentially the same thing as GM's technology but does it in a fairly different way due to the Mercedes engines' overhead cam design. Mercedes claims this new V-12 gets 20 percent better fuel economy and meets lower emission levels than the previous V-12, and much of this is attributable to the cylinder-deactivation feature."





from

http://car-reviews.automobile.com/news/industry-report-expanding-displacement-efficiency-to-improve-fuel-economy/495/

"With complexity and cost in mind DOD was first shown in Cadillacs V12 Cien concept car, and will be available in the V12 powered Escalade. Basically the system uses GMs eMotion powertrain control system to close the intake and exhaust valves on specific cylinders, effectively turning off half the cylinders, which improves fuel economy by around 8 to 10 percent."

[VRIIClubby]

wasnt the reason it was dropped from the LS2 because of drivetrain vibration issues that they couldn't stop when it shut down to 4 cylinders, was a lengthy post on here some time ago but i cannot seem to find it atm..

argh just found some links...

http://www.ls1.com.au/forum/showthread.php?t=24425&highlight=DoD

[Ghostdriver]

Have sampled the equivalent system in a Chrysler 300C. It is excellent.

[OzJavelin]

Have sampled the equivalent system in a Chrysler 300C. It is excellent.
Tell us more about the 300C? What's it like to drive? When I was in USA last year I *SHOULD* have hired one .. there were heaps around!!

[BULLET]

Real world I read somewhere abt 8% gain. GMs version will jump from 8 to 4 cyls only no 6 cyl because of engine vibration, which was one of the complaints with Caddy version. The electronics will handle throttle posn. etc but the pedal won't move. The valves on the "dead" cylinders dont move at all, the power it takes to compress the air in those cyls is almost all regained when the compressed air pushes the piston down on the next part of the stroke, according to GM. I thought this info came from a link on this site. No doubt an avid forum watcher will advise! :)

[chevypower]

Early on there was talk of DOD being built into the LS2, but GM dropped it for some reason. They used to have it years ago in the "infamous" Caddy V8 (4.1L I think?) .. it was terrible, but that was early days. What Mopar are doing with the Hemi is the modern incarnation of this. I think it's basically shutting down cylinders by control of the injectors and lifters. However the system does not shut them down completely; it reactivates cylinders periodically to keep them "healthy". This - and the fact of the additional drag of the "dead cylinders" - is why they don't get a 50% fuel decrease .. more like 20% at most. But these things were basically introduced to keep big V8s in American SUVs, so any saving would be welcome.

GM and Ford will have to introduce their own systems soon, but they are probably smart to wait and see how the Mopar system goes .. both techncially and acceptance by the public?

Good point, even if they removed half the engine from the vehicle, you couldnt get 50% saving, because you are moving the same vehicle, putting in more effort to do it - if you push a shopping trolley with 1 hand or with 2, 2 is easier, but you dont use more energy to do it. Also V8s dont use a lot of fuel when they are not working hard, and the only time DOD will shut half the engine, is when it is not using much fuel anyway, even if DOD still kept it on 4cyls when it was working, it would probably chew through the juice just as much as it would with 8 cyls working, and offer no power - but they don't do that, so 20% saving in my opinion is an over estimate, hence the 5.7L in the Jeep still uses slightly more fuel than the 4.7L without DOD - in theory even without the DOD, the 4.7 and 5.7 in the same vehicle should have comparable fuel consumption, the proof is in the pudding, and DOD is just a marketing tool. Having said all that , i still wouldnt mind a nice new Hemi

[VTSS350]

Yes but think about having a V12 engine.

Cruise along on the highway and you could be running on 4 or 6 cylinders using less fuel than 12.

Then put your foot down and have a seamless transition to 8, 10 or 12 cylinders.

Even a 10% saving is a good saving and I would say it would be closer to the 20% stated allready.


A V6 commodore gets better economy than the V8 so with DOD it would allow you to drive it like your NANA to save on fuel and still be able to have those trafic light drags. For me its a win win situtation.

[V-Car]

DoD is currently only used on the LH6 5.3lt version of the Gen IV.


GM’s Displacement on Demand (DOD) technology debuts in 2005 GM extended midsize SUVs equipped with the Vortec 5300 5.3L V-8 (LH6). DOD technology enables fuel economy gains of up to 8 percent in certain light-load driving conditions by reducing the number of cylinders engaged in the combustion process. A sophisticated, next-generation engine controller determines when to deactivate cylinders, allowing the engine to maintain vehicle speed in lighter-load conditions such as highway cruising. When the cylinders are deactivated, the engine effectively operates as a V-4, with alternate cylinders on each cylinder bank disabled. The engine returns to V-8 mode the instant the controller determines the vehicle speed or load requires additional power. The process is seamless and virtually imperceptible.

http://www.gm.com/automotive/gmpowertrain/tech/pdf/DoD.pdf