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Thats what im told. The key words were "wow" "incredible" "you wont believe how nice they look" "pretty amazing what theyve done" "game changer".
I've heard this before like when the present gen. trucks came out so i'll beleave it when i see it.:)
 

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From what I have heard from service people and engineers, only the 2007 models have the knock at startup/idle. GM made several changes on the 2008 engines to prevent the tick/knock noise.
Then why does the 5.3L in my '08 tick/knock about 50% of the time with a cold start?

I disabled my AFM as well because I was noticing a very small, but definitely present use of oil. Same with our '09 Envoy Denali's 5.3L. Now neither engine loses a drop.
 

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If you guys don't want the fuel economy gadgetry...get the HD. My next truck will be an HD.
If I could get an HD crew cab with the short bed (5'8") I would have a Denali HD in my driveway right now. If the next gen makes this available, I just might do it.
 

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Discussion Starter · #44 ·
350 hp is too low. the mainstream hemi has 390...toyota over 400....those are their mainstream engines- i know they offer smaller v8s but no one buys those. if gm really wanted to leapfrog everyone the v6 would have 325-350 hp. 5.3 400. 6.2 475.



so theyre using cars to design trucks?:(
we'll have to wait and see it seems.
That means to say GM is choosing a design language for all of chevy. It looks good on most but not necessarily converts to the trucks. It sounds to me like the chevy will have a more "work truck" like look while using the chevy split grill but not in the same way as the current ones plain look. The more aggressive grill on the 2013 malibu is kinda what im thinking was meant.

Im not trying to downplay the chevy but the word is chevy will look less upscale than the new GMC. You gotta remember that GMC has the ability to go wild with their design while chevy needs to cater to everyone. That means GM can leapfrog a few generations of evolving GMC style and go for the juggular of the competition, and that is what im hearing.

The GMC will be the sonic boom to the industry while the chevy placates the masses.
 

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GM had better stop the bs and put E-assist on the damn V8s. No reason not to. Come on now, come on.

I hope they don't mess these trucks up. I love my Avy and think the 900s are the best no matter what Ford or Dodge are doing.
 

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Only thing I'm dissapointed with about the news is the low HP figure for the 5.3 liter. It needs to match the Ford 5.0.
6.2 l v8 with 425 hp and 5.3 l with 350 HP.
About same HP/l..I don't see GM developing 400 hp 5.3 l v8 and 6.2 l v8 staying on 425 hp..maybe 6.2 l v8 with 470 hp..but since 5.3 is rumored to be truck only verison i don't see this engine coming close to 400 HP. I hope i'm wrong.:)
 

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Bvonscott,

I'm just curious, did you hear anything about a twin turbo V6 to compete with the F-150 Ecoboost engine?

I'm not sure GM needs it to compete, since GM will have cylinder deactivation and direct injection in its V8s and Ford does not. But if they are going to make trucks like that, I would like to know about it.

But, problem-free or not....AFM does NOT make any significant impact on FE. I noticed ZERO difference in MPGs with AFM disabled. AFM is a good idea for cars, but to think that a 5500lb truck with the aerodynamics of a brick can run on 4 cyls is simply ludicrous. My truck only would go into 4-mode while decelerating or while cruising at under 60 MPH on a completely flat freeway...and then it would rarely stay in 4-mode. One time I was able to get it to stay in 4-mode at 60 MPH with the cruise on and I turned on the AC and it kicked it back into V8 mode :lmao:

They should at the very least make it 8/6 instead of 8/4. It can't be that hard. My wife's Accord has it and it is a 6/4/3 system and it works flawlessly with no drone and it is 100% seamless. The AFM in my truck was seamless too, except it would cause the TCC to lock/unlock at times and that was noticeable and irritating. Good riddance AFM!
VMax2007,

I'm sorry your truck gave you so many problems. But consider the following improvements the next Silverado and Sierra will probably have to make Active Fuel Management work better:

1. The trucks may use more high strength steel in order to be lighter without losing strength. A lighter vehicle is easier to push in 4 cylinder mode.
2. The trucks may be more aerodynamic. That also makes them easier to push in 4 cylinder mode.
3. The truck will have six gears in the transmission instead of four. That gives the computer more options for what RPM to use in four cylinder mode, maybe when it switches to four cylinder mode it drops a gear or two to raise the RPMs slightly. That will raise the power coming from the four cylinder engine but still keep fuel consumption below running in eight cylinder mode.
4. These will be more powerful engines with direct cylinder fuel injection and variable valve timing to improve torque across the whole RPM range. So even with four cylinders off it will be making a much better output.

These are my wild guesses, I don't know what the reality will be. But I'm hopeful GM will get really good EPA ratings and real world fuel economy with the next trucks.
 

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VMax2007,

I'm sorry your truck gave you so many problems. But consider the following improvements the next Silverado and Sierra will probably have to make Active Fuel Management work better:

1. The trucks may use more high strength steel in order to be lighter without losing strength. A lighter vehicle is easier to push in 4 cylinder mode.
2. The trucks may be more aerodynamic. That also makes them easier to push in 4 cylinder mode.
3. The truck will have six gears in the transmission instead of four. That gives the computer more options for what RPM to use in four cylinder mode, maybe when it switches to four cylinder mode it drops a gear or two to raise the RPMs slightly. That will raise the power coming from the four cylinder engine but still keep fuel consumption below running in eight cylinder mode.
4. These will be more powerful engines with direct cylinder fuel injection and variable valve timing to improve torque across the whole RPM range. So even with four cylinders off it will be making a much better output.

These are my wild guesses, I don't know what the reality will be. But I'm hopeful GM will get really good EPA ratings and real world fuel economy with the next trucks.
Good points, but doesn't the bolded part of #3 seem a bit counterproductive? 6 speeds with 2 ODs was meant to improve fuel efficiency and I am betting it is far more successful at it then AFM could ever dream of.

I am very skeptical that a 8/4 AFM system will ever amount to any real world FE increases in full size trucks. I think it's just a way to boost the EPA ratings to help with CAFE.
 

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Engines are most efficient at the point where they produce peak torque, not when they're practically idling. Running on four cylinders at a higher RPM with less throttle loss is more efficient than on eight cylinders when the throttle is nearly closed.
 

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Engines are most efficient at the point where they produce peak torque, not when they're practically idling. Running on four cylinders at a higher RPM with less throttle loss is more efficient than on eight cylinders when the throttle is nearly closed.
Then why does GM and everyone else keep adding OD gears?

Yes, VE may be highest at or near peak TQ, but fuel consumption is higher at higher RPMs.
 

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Then why does GM and everyone else keep adding OD gears?

Yes, VE may be highest at or near peak TQ, but fuel consumption is higher at higher RPMs.
But brake specific fuel consumption from an air-throttled engine is lower when it's at peak VE, which is exactly why AFM exists in the first place.

Overdrive has been around a lot longer than the ability to safely run a vehicle on half of its cylinders. As Cadillac proved, the technology just wasn't there not too long ago. I think that for efficiency's sake the best scenario would be an engine that is operating at WOT to make only the amount of power it takes to maintain the current speed. With low rolling resistance tires and decent aerodynamics, that means you'd only need about 40hp to keep up with traffic, which means you wouldn't need much power at all, but you'd accelerate like a slug.
 

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But brake specific fuel consumption from an air-throttled engine is lower when it's at peak VE, which is exactly why AFM exists in the first place.

Overdrive has been around a lot longer than the ability to safely run a vehicle on half of its cylinders. As Cadillac proved, the technology just wasn't there not too long ago. I think that for efficiency's sake the best scenario would be an engine that is operating at WOT to make only the amount of power it takes to maintain the current speed. With low rolling resistance tires and decent aerodynamics, that means you'd only need about 40hp to keep up with traffic, which means you wouldn't need much power at all, but you'd accelerate like a slug.
In theory, AFM makes sense...but in real world experience, it does absolutely nothing. I know, I have run my truck for extended periods each way in all types of conditions and have never seen any increase or decrease in FE with AFM enabled vs disabled. It adds complexity and has more potential issues (real issues for many) than it's worth.

Will it be better in the new trucks? I hope so, but I seriously doubt it.
 

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6.2 l v8 with 425 hp and 5.3 l with 350 HP.
About same HP/l..I don't see GM developing 400 hp 5.3 l v8 and 6.2 l v8 staying on 425 hp..maybe 6.2 l v8 with 470 hp..but since 5.3 is rumored to be truck only verison i don't see this engine coming close to 400 HP. I hope i'm wrong.:)
While it's not the identical engines that are being discussed, Cadillac had 2 versions of the hfV6, with and without di. The di engine produced 15% more power and 6% better fuel economy.
If the same percentage was available for the 5.3 and 6.2, the 320 hp engine would produce 368 horsepower and the 6.2 with 403 hp would produce 465 hp. Even down-rated a bit could easily be 350 hp and 450 hp.:)
 

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I'm under the impression that the new V6 will be a Gen V SBC with two less cylinders, not a HFV6.

I can't wait for more news on the new 4-Mode hybrids. I'm hoping to put one of those in my grandparents' garage.
 

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Anyone vote for more AFM whining?
Maybe we need an AFM whining thread.

GM really stepped it up in each of the prior two truck generations.
Expect to see more use of aerodynamics to help maximize fuel economy.
The next generation design; interior, exterior, safety, ruggedness, and fuel economy need to be all home runs.
 

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How about a turbo V8 :D

I really hope the new interiors are on par with or better than Ford's. The rear section of all the current GM trucks/suv's is a huge reason why I'm at least waiting for the next generation to come out. I want big rear seat and storage areas, and a better center console and bigger buttons for functionality. The King Ranch super duty is about the nicest interior in any real car on the market today.
 

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The best part: the Sierra looks PHENOMINAL and will blow people away, and doesnt look like a chevy, which will be the more "work truck" kinda feel and more "vanilla". Sorry Chevy guys. GM is aiming to increase GMC sales ALOT.
That means to say GM is choosing a design language for all of chevy. It looks good on most but not necessarily converts to the trucks. It sounds to me like the chevy will have a more "work truck" like look while using the chevy split grill but not in the same way as the current ones plain look. The more aggressive grill on the 2013 malibu is kinda what im thinking was meant.

Im not trying to downplay the chevy but the word is chevy will look less upscale than the new GMC. You gotta remember that GMC has the ability to go wild with their design while chevy needs to cater to everyone. That means GM can leapfrog a few generations of evolving GMC style and go for the juggular of the competition, and that is what im hearing.

The GMC will be the sonic boom to the industry while the chevy placates the masses.
If a single word of any of that is true I'm done. 90 Years of Chevrolet family loyalty ends.. I will never step foot in a gmc. I have far too much pride to reduce myself to such a brand.. GM can go straight to hell as far as I'm concerned. I wouldn't even keep my old Chevrolet's around a day longer. For me, the bailouts were nothing. This however brings out a hatred in me for GM like I've never felt.


Ford trucks and Ford cars here I come... I hope you'll welcome an Ex Chevrolet guy with open arms. I refuse to support a 'second best' brand another day of my life in any way, shape or form. At least with Ford you'll get the best they have to offer. I can't stand this 2 truck brand BS any longer. Fake as fake could be... Nothing real anymore.
 

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When I read this thread, you were the first person I thought of. I knew that news like this would be devastating to you............. and rightfully so.

So, GM is going to tell their loyal Chevrolet fans that they are not very important, and need to get used to bland and boring. Any flavor you want............... as long as it is vanilla. What a nice way to insult your most fervent fans.

Hopefully this information is not correct.
 
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