GM Active Fuel Management (AFM) system (1/2 the cylinders turn off when cruising)

[JEDI]

Link

"Cylinder deactivation is an automatic switch from six cylinders to three when the load is light. This means that, for example, on long, flat highway drives, the engine will not burn as much gasoline. "

i guess the biggest benfit will be those 8cyl cars.

I wonder how much more will it cost over the same car w/an regular engine?

ie:
cost effiency of a getting a 4cyl car w/AFM when you drive 90% highway?

 

[Toastedlightly]

Isn't this already in use?

 

[xanis]

Originally posted by: Toastedlightly
Isn't this already in use?

I beleive so, on some of the big V8 Chevys.

 

[sniperruff]

Originally posted by: Toastedlightly
Isn't this already in use?

i guess this is new for 6 cyilnder's.

"Chevy announced that "Preliminary testing of the 2007 Chevy Impala equipped with the 3.9L V-6 with AFM indicates an estimated 20 mpg in the city and 29 mpg on the highway ? improvements of approximately 5.5 percent and 7.5 percent, respectively.""

i got all excited about nothing. the accord V6 already does that and the camry V6 beats that.

 

[Fenixgoon]

Originally posted by: Xanis

Originally posted by: Toastedlightly
Isn't this already in use?

I beleive so, on some of the big V8 Chevys.

chrysler also has Multi-Displacement System(MDS).. same thing, deactivates 4 cylinders

 

[sciencewhiz]

How do they keep it balanced on a V6?

 

[AE86Lover]

welcome to the early 90's. Benz already implemented this system in their cars but on a platform for 12 cylinders.

 

[Strk]

Originally posted by: Toastedlightly
Isn't this already in use?

They use it on the Yukon.

 

[Howard]

Originally posted by: sciencewhiz
How do they keep it balanced on a V6?

You don't have to. It's the movement of mass, not the forces that determine "balance". AFAIK.

 

[MikeMike]

Originally posted by: Howard

Originally posted by: sciencewhiz
How do they keep it balanced on a V6?

You don't have to. It's the movement of mass, not the forces that determine "balance". AFAIK.

the V6 still has all cylinders pumping when in V3 mode, it just stops fuel going into those pistons, and uses the compressed exhaust to push itself back down, aka, no injector opens up.

 

[GoingUp]

Chryslers been using it for quite some time too on their HEMI engines.

 

[MikeMike]

Originally posted by: Gobadgrs
Chryslers been using it for quite some time too on their HEMI engines.

GM started it WAYYYY back in the 1980's with the 8-6-4 implementations, but back then, they didnt have the technology we do now, and they failed, miserably.

 

[Linflas]

Originally posted by: MIKEMIKE

Originally posted by: Gobadgrs
Chryslers been using it for quite some time too on their HEMI engines.

GM started it WAYYYY back in the 1980's with the 8-6-4 implementations, but back then, they didnt have the technology we do now, and they failed, miserably.

That's how I remember it as well. I think they rolled it out on some Cadillacs and failed big time.

 

[Howard]

Originally posted by: MIKEMIKE

Originally posted by: Howard

Originally posted by: sciencewhiz
How do they keep it balanced on a V6?

You don't have to. It's the movement of mass, not the forces that determine "balance". AFAIK.

the V6 still has all cylinders pumping when in V3 mode, it just stops fuel going into those pistons, and uses the compressed exhaust to push itself back down, aka, no injector opens up.

You mean I3. 😉

Uses the compressed exhaust to push what down?

 

[GuitarDaddy]

I've been driving an 06 Impala SS with the 5.3l (DOD) V8 since march. I really like the car so far, the DOD probably only gives you and extra 2-3mpg under normal city driving condition. On the highway it seems like you get an extra 5-7mpg.

I think what kills the mileage for city driving is that anytime your less than 20mph it stays in 8cyl mode, which means at stop signs, red lights, stop and go traffic your always in 8cyl mode. And in traffic you can never drive in the most fuel efficent manner, if you were by yourself on the road and drove to maximize mileage you could get some crazy good mileage.

The car is rated 18city 28hwy, but with my lead foot and heavy traffic conditions I've been getting 17city. The one highway trip I made the car was 2 weeks old, and I definately lead footed it and drove 80-85 and got 26mpg.

 

[biggestmuff]

Originally posted by: AE86Lover
welcome to the early 90's. Benz already implemented this system in their cars but on a platform for 12 cylinders.

Try 1981 with the CADILLAC V8-6-4.

 

[JEDI]

Originally posted by: sniperruff

Originally posted by: Toastedlightly
Isn't this already in use?

the accord V6 already does that and the camry V6 beats that.

are these special models for the accord/camry? or is it standard no matter the trim? if the former, how much more does it costs?

 

[acemcmac]

Originally posted by: biggestmuff

Originally posted by: AE86Lover
welcome to the early 90's. Benz already implemented this system in their cars but on a platform for 12 cylinders.

Try 1981 with the CADILLAC V8-6-4.

interesting...

 

[ts3433]

Edited: I am an idiot.

 

[GuitarDaddy]

Originally posted by: acemcmac

Originally posted by: biggestmuff

Originally posted by: AE86Lover
welcome to the early 90's. Benz already implemented this system in their cars but on a platform for 12 cylinders.

Try 1981 with the CADILLAC V8-6-4.

interesting...

Yep, I believe the Caddy was the first to implement the technology and it was a fairly problematic engine for them. Probably why it was 10+ years before anyone else tried it, and 20+ years before GM returned to it.

 

[TripleAAA]

It's used on the Saab SUV as well.

 

[ElFenix]

Originally posted by: ts3433

Originally posted by: JEDI

Originally posted by: sniperruff

Originally posted by: Toastedlightly
Isn't this already in use?

the accord V6 already does that and the camry V6 beats that.

are these special models for the accord/camry? or is it standard no matter the trim? if the former, how much more does it costs?

No; what sniperruff's saying (I think) is that the Accord's (non-hybrid; 20/29 with 5AT) and Camry's (22/31 with 6AT) V6 engines match or beat the fuel economy of the Impala's new V6 without having to implement cylinder deactivation. The Accord V6 Hybrid does add cylinder deactivation, though, but that's not a very good comparison.

smaller motors in smaller cars...

 

[MasterAndCommander]

My Mustang has something called "limp home" mode where half the cylinders shut down in the event of a coolant failure and act as air pumps for the engine. It would be intersting to see what kind of mileage it gets under those conditions...though I never want to find out.

 

[thedarkwolf]

Originally posted by: ts3433

Originally posted by: JEDI

Originally posted by: sniperruff

Originally posted by: Toastedlightly
Isn't this already in use?

the accord V6 already does that and the camry V6 beats that.

are these special models for the accord/camry? or is it standard no matter the trim? if the former, how much more does it costs?

No; what sniperruff's saying (I think) is that the Accord's (non-hybrid; 20/29 with 5AT) and Camry's (22/31 with 6AT) V6 engines match or beat the fuel economy of the Impala's new V6 without having to implement cylinder deactivation. The Accord V6 Hybrid does add cylinder deactivation, though, but that's not a very good comparison.

Impalla is a large sedan and the accord and camry are both midsized sedans so they better get more MPG.

 

[RU482]

Originally posted by: acemcmac

Originally posted by: biggestmuff

Originally posted by: AE86Lover
welcome to the early 90's. Benz already implemented this system in their cars but on a platform for 12 cylinders.

Try 1981 with the CADILLAC V8-6-4.

interesting...

wow, another hour lost to Wikipedia click throughs