[gpac]

Does anybody have any information re: the cylinder reduction feature on the new 2007 Suburbans? I have heard that GM tried this about 10 years ago and it failed big time. I want to get a 2007 but am a little hesitant about the quality of this new feature and how it will perform. Any thoughts?

 

[84fiero123]

Get the next years, if 07 is the first get the 08 buy then they should have it right, hopefully.

I thought they did it in the 70’s or 80’s.

I was working for GM back then and remember Caddy having the V8/6/4.

But technology has come a long way in 30 years, I hope it does work. It would be great to drive a Burb with highway mileage in the 30 mpg range. :mrgreen:

 

[nemopoppins]

I'm still reeling from the sluggishness of my old 86 Suburban. I'd easily give up mileage for power. Will they still be offering the traditional Vortec?

 

[newdev]

Fab

I have a new one. Got it in December. The v4 to v8 is great! and does improve the mileage read out to 22 to 24mpg BUT any type of added load like the A/C or a lot of wind does not allow the switching to V4. I have had absolutely no problems with that end. Did have other problems and Chevy came to the plate. I had a trany that would not go into overdrive and Chevy Lemon lawed the vehicle for me. But with the interim rentals and the new one I have had no problems with the engine/trans

 

[wildmans92]

basic overview

Well alot of research has gone into this system, and i am working for a gm dealer. basically the engine cuts fuel to four of the cylinders, then it deactivates the lifters on those cylinders via an oil control solenoid. This allows the cylindrs to act as an air spring. And yes it is very sensitive and kicks back to 8 at the slightest load increase.

 

[abuelito]

Well alot of research has gone into this system, and i am working for a gm dealer. basically the engine cuts fuel to four of the cylinders, then it deactivates the lifters on those cylinders via an oil control solenoid. This allows the cylindrs to act as an air spring. And yes it is very sensitive and kicks back to 8 at the slightest load increase.

i have the yukon xl,,,i have over 3000 miles on it,2007,,,no problems ,,2000 miles are here in mexico,,,,,on high way it moves in and out ,,,helps on gas milage,,,here in mexico i am on dirt roads and rock roads 90 percent of the time ,,,,no problems so far,,,abuelito

 

[Crawdaddy]

The technology behind it has always amazed me, but I heard it was a huge flop back when they tried it the first time. Perhaps now that the computers for the motors have advanced so much, it may be able to do a better job. The thing that's always gotten me though is that, sure, you shut cylinders down, but you're still dragging that piston up and down the cylinder which creates a good bit of drag on the rest of the motor, causing the remaining cylinders to have to work harder to achive the same effect. Unless you can completely disengage the piston from the crank, then the drag I would think is so immense that a significant change is fuel economy cannot be realized.

 

[TrailLeadr]

The technology behind it has always amazed me, but I heard it was a huge flop back when they tried it the first time. Perhaps now that the computers for the motors have advanced so much, it may be able to do a better job. The thing that's always gotten me though is that, sure, you shut cylinders down, but you're still dragging that piston up and down the cylinder which creates a good bit of drag on the rest of the motor, causing the remaining cylinders to have to work harder to achive the same effect. Unless you can completely disengage the piston from the crank, then the drag I would think is so immense that a significant change is fuel economy cannot be realized.

That's what I always figured but if they leave the valves closed the the air would act like a spring, just like wildman92 said. Once the piston hits the bottom of it's stroke it would have negative pressure encouraging the piston to come back up, and once it hits the top it will have high pressure which will encourage the piston to move back downward.
Kind of on the principal of the sterling engine.
http://en.wikipedia.org/wiki/Sterling_engine

 

[unplugged]

questionable from an investment standpoint

FYI,

From: http://www.fueleconomy.gov/feg/tech_engine_more.shtml#dod

This website explains the underlying technology and claims that the typical savings over the LIFETIME of the vehicle is only $2000. That doesn't sound like grounds for exposing yourself to potentially expensive trouble maintaining the system.

Trippy looking lifters that GM uses:

 

[84fiero123]

Doesn’t someone else also have this set up.

Toyota or Honda ?

I’m not sure but I thought I heard they did.

 

[unplugged]

Nissan and Honda

Doesn’t someone else also have this set up.

Toyota or Honda ?

I’m not sure but I thought I heard they did.

Nissan and Honda use VVEL Variable Valve Event Lift and continuous valve timing control (C-VTC) to deliver significantly enhanced performance.

From: Autospies.com

 

[fierodough]

Not the same result, but the Northstar cycles through cylenders in limp home / overheating conditions.

(I can't beleive how smart this system is!!!) During an overheating situation. ie: Coolant loss. The Northstaqr will cut fuel and spark to a cylinder and suck cold air in to reduce heat. Then it will do this on another cylinder ect. Self preservation!!! And if equiped with OnStar, will call in to get you assistance!

Damn cars / trucks have come a long way!

 

[Cableguy]

Article I found on this subject, kinda interesting...
http://www.carpages.ca/go/autonews/12182005,active_fuel_management_to_replace_gms_displacement_on_demand.aspx