# 2020 GM HD 6.6 Gas - 401 hp and 464 pound-feet of torque



## Cosmic Charlie (Feb 1, 2009)

Yup, you read that right: the all-new GM 6.6L V-8 L8T gasoline engine for the all-new 2020 Chevrolet Silverado HD and 2020 GMC Sierra HD is not equipped with Active Fuel Management (AFM), Dynamic Fuel Management (DFM), or Auto Stop-Start, _GM Authority_ confirmed with GM.

The absence of the fuel-saving technologies is noteworthy, given customer complaints about all three features. For instance, the first iteration of AFM was known to cause some vehicles to shake when the engine switched from 8-cylinder to 4-cylinder mode. Meanwhile, Auto Stop-Start has been the source of all kinds of complaint, causing owners to actively look for ways to disable it. Luckily, we have yet to hear a single complaint about DFM - though that may change as more vehicles with the technology hit the streets.

*On a related note, we were also able to find out the recommended fuel rating for the L8T as 87 octane. As such, the direct-injected engine doesn't need the pricey stuff to make its 401 horsepower and 464 pound-feet of torque in the 2020 Silverado HD and 2020 Sierra HD.*

Stay tuned to GM Authority as we learn more about the L8T, and for ongoing GM news coverage.






http://gmauthority.com/blog/2019/02...ne-no-active-fuel-management-auto-stop-start/


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## Mr.Markus (Jan 7, 2010)

Integrated the block heater plug into the bumper. I gotta buy one now...


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## 1olddogtwo (Aug 6, 2007)

It seems GM keeps tripping over it self.


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## leolkfrm (Mar 11, 2010)

they did away with bb gas and pushed diesel, now they are finding people want bigger gas engines, as they dont want to deal with diesel...even freightliner is working with gas engines again


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## 1olddogtwo (Aug 6, 2007)

http://gmauthority.com/blog/2019/01...orse-fuel-economy-than-v8-in-real-world-test/


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## extremepusher (Aug 24, 2011)

Key thing is, will the frame crack in half above the front axle like the last 15 yr models? If it has a diesel motor and put a plow on it will it void the warranty like in years past? So what good is all hp if these things aren't resolved?


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## the Suburbanite (Jan 27, 2018)

leolkfrm said:


> they did away with bb gas and pushed diesel, now they are finding people want bigger gas engines, as they dont want to deal with diesel...even freightliner is working with gas engines again


Happily hanging on to my 8.1's


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## CCSnow (Jan 25, 2016)

Don't want to work on that 2.7 motor... 4-5 foot hood and they cram everything into 2 feet.


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## Mark Oomkes (Dec 10, 2000)

1olddogtwo said:


> http://gmauthority.com/blog/2019/01...orse-fuel-economy-than-v8-in-real-world-test/


So basically everyone but the EPA understands that loading an engine causes worse fuel economy? No replacement for displacement.


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## Four Seasons (Jan 7, 2008)

Good looking truck


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## Mark Oomkes (Dec 10, 2000)

10 speed transmission???

Is there a contest between the 3 as to who can make the ugliest grille/front end?


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## LapeerLandscape (Dec 29, 2012)

Mark Oomkes said:


> 10 speed transmission???
> 
> Is there a contest between the 3 as to who can make the ugliest grille/front end?


GMC is not in that contest, that truck looks good.


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## Mark Oomkes (Dec 10, 2000)

LapeerLandscape said:


> GMC is not in that contest, that truck looks good.


What straight guy wants to drive a GMC???


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## the Suburbanite (Jan 27, 2018)

LapeerLandscape said:


> GMC is not in that contest, that truck looks good.


Now put it on an HD Suburban.


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## NYH1 (Jan 10, 2009)

If I'm not mistaken, I think someone posted that TFL video not long ago....

NYH1.


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## GMC Driver (Sep 9, 2005)

Mark Oomkes said:


> What straight guy wants to drive a GMC???


Nothing is sacred.

I'm a GMC driver that identifies as a warm blooded heterosexual male. Even if that puts me in bad company.


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## Philbilly2 (Aug 25, 2007)

Mark Oomkes said:


> What straight guy wants to drive a GMC???


Why so much hate???


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## Philbilly2 (Aug 25, 2007)

Mark Oomkes said:


> 10 speed transmission???


The new 10 speed is unreal.

Wife's Yukon has it. Almost feels like a CVT... just keeps pulling.


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## 1olddogtwo (Aug 6, 2007)

I thought you didn't like Ford.


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## Newdude (Dec 4, 2006)

extremepusher said:


> Key thing is, will the frame crack in half above the front axle like the last 15 yr models? If it has a diesel motor and put a plow on it will it void the warranty like in years past? So what good is all hp if these things aren't resolved?


Where have you been!?!?

As of 2011 when they made the new HD frame, ALL cabs and engines have VYU Plow prep as an option. The frames are totally different than the 01-10 frame. No cracks. 6000lbs FGAWR on diesel trucks with VYU.

Seems you have some catching up to do...


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## Philbilly2 (Aug 25, 2007)

1olddogtwo said:


> I thought you didn't like Ford.


Who?


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## 1olddogtwo (Aug 6, 2007)

Philbilly2 said:


> Who?


The 10 speed "Allison-branded" is a co-development between GM and Ford.


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## Philbilly2 (Aug 25, 2007)

1olddogtwo said:


> The 10 speed "Allison" is a co-development between GM and Ford.


I was speaking of the 10 speed attached to the LS motor.

As for the Allison... as long as it was not left in the hands of Ford alone it should work well. :laugh:

Nice to see that Ford is finally figuring out what GM has known since 2001 though... Thumbs Up


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## Philbilly2 (Aug 25, 2007)

1olddogtwo said:


> I thought you didn't like Ford.


And it is not that I don't like Ford... I just think that they are junk...  :laugh:


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## GMC Driver (Sep 9, 2005)

1olddogtwo said:


> The 10 speed "Allison-branded" is a co-development between GM and Ford.


2 different transmissions. The one on the LP5 is an Allison. The 10 speed behind the 6.6 gas and the Ford 7.3 is co-developed.


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## Triple L (Nov 1, 2005)

I thought the 6.6 gas got the 6 speed transmission?


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## GMC Driver (Sep 9, 2005)

You might ne right Chad - thought I read 10 speed somewhere. Maybe that's 1/2 tons...


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## Mark Oomkes (Dec 10, 2000)

GMC Driver said:


> You might ne right Chad - thought I read 10 speed somewhere. Maybe that's 1/2 tons...


Cars???


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## Randall Ave (Oct 29, 2014)

Philbilly2 said:


> And it is not that I don't like Ford... I just think that they are junk...  :laugh:


Don't beat around the bush, tell us how you really feel.


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## tpendagast (Oct 27, 2012)

extremepusher said:


> Key thing is, will the frame crack in half above the front axle like the last 15 yr models? If it has a diesel motor and put a plow on it will it void the warranty like in years past? So what good is all hp if these things aren't resolved?


That and for the low low price of 75,000 you too to have the privilege of 6 mpg!


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## Drock78 (Sep 22, 2011)

Its about time GM got into the gas game! The 6.0 while reliable, is severely underpowered for a HD truck. Although the 6.6 will still be the lowest hp between the big 3, it will be an improvement over the 6.0. The sole reason I didn't buy another GM was because of the 6.0


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## Philbilly2 (Aug 25, 2007)

GMC Driver said:


> 2 different transmissions. The one on the LP5 is an Allison. The 10 speed behind the 6.6 gas and the Ford 7.3 is co-developed.





Triple L said:


> I thought the 6.6 gas got the 6 speed transmission?





GMC Driver said:


> You might ne right Chad - thought I read 10 speed somewhere. Maybe that's 1/2 tons...


This is my fault... :laugh:

My wife's Yukon has the 6.2L gasser (L86) with a 10 speed transmission(10R90)

The new Duramaxes (LP5) equipped 2020 will have an "Allison" 10 speed

The new 6.6 gasser(LT8) will have a 6 speed


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## Philbilly2 (Aug 25, 2007)

Drock78 said:


> Its about time GM got into the gas game! The 6.0 while reliable, is severely underpowered for a HD truck. Although the 6.6 will still be the lowest hp between the big 3, it will be an improvement over the 6.0. The sole reason I didn't buy another GM was because of the 6.0


They are not done with just another a small block from what I have heard...

http://gmauthority.com/blog/2019/02/gm-planning-new-engine-larger-than-new-6-6l-v8-l8t/


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## FredG (Oct 15, 2012)

Philbilly2 said:


> This is my fault... :laugh:
> 
> My wife's Yukon has the 6.2L gasser (L86) with a 10 speed transmission(10R90)
> 
> ...


 I thought GM owned Allison, why would you team up with Furd just making them more desirable with the Allison. Should of teamed up with Dodge the Cummings and the Allison would be a bad to the bone truck.


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## LapeerLandscape (Dec 29, 2012)

Philbilly2 said:


> This is my fault... :laugh:
> 
> My wife's Yukon has the 6.2L gasser (L86) with a 10 speed transmission(10R90)
> 
> ...


I thought the trans on the 6.2 was an 8 speed but I could be wrong.


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## Mark Oomkes (Dec 10, 2000)

FredG said:


> I thought GM owned Allison, why would you team up with Furd just making them more desirable with the Allison. Should of teamed up with Dodge the Cummings and the Allison would be a bad to the bone truck.


I thought Ventrac owned Cummings and Allison?


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## FredG (Oct 15, 2012)

Mark Oomkes said:


> I thought Ventrac owned Cummings and Allison?


 SKW, that's nice. :laugh:


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## Philbilly2 (Aug 25, 2007)

LapeerLandscape said:


> I thought the trans on the 6.2 was an 8 speed but I could be wrong.


It was up until 2018, when they released a new 10 speed.


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## Philbilly2 (Aug 25, 2007)

FredG said:


> I thought GM owned Allison, why would you team up with Furd just making them more desirable with the Allison. Should of teamed up with Dodge the Cummings and the Allison would be a bad to the bone truck.


They did until 2007 when it was sold to Carlye Group. (Might be wrong on the spelling)


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## Mark Oomkes (Dec 10, 2000)

Philbilly2 said:


> It was up until 2018, when they released a new 10 speed.


Schwinn 10 speed???


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## LapeerLandscape (Dec 29, 2012)

Philbilly2 said:


> It was up until 2018, when they released a new 10 speed.


Ok got it.


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## GMC Driver (Sep 9, 2005)

Mark Oomkes said:


> Schwinn 10 speed???












??


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## LapeerLandscape (Dec 29, 2012)

Mark Oomkes said:


> Schwinn 10 speed???


Have to go with the Schwinn, the Huffy was the Harbor Freight of bikes.


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## Philbilly2 (Aug 25, 2007)

Mark Oomkes said:


> Schwinn 10 speed???


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## EWSplow (Dec 4, 2012)

Philbilly2 said:


> This is my fault... :laugh:
> 
> My wife's Yukon has the 6.2L gasser (L86) with a 10 speed transmission(10R90)
> 
> ...


You didn't get your wife the 1000 HP Yukon?


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## Philbilly2 (Aug 25, 2007)

EWSplow said:


> You didn't get your wife the 1000 HP Yukon?


I spent enough on this one as it is...  no need to get silly


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## Cosmic Charlie (Feb 1, 2009)

For 2020 GM HD 2500/3500

Final Drive Ratio:

3.73 (6.6L gas)
3.42 (6.6L diesel)



Current

6.0L

360 HP @5400RPM

380 TQ @4200RPM

Port injection

9.7:1 Compression ratio

87 octane. No AFM / DFM

GM 6 Speed Automatic



2020 6.6L L8T 

6.6L

401 HP @5200RPM

464 TQ @4000RPM

Direct injection

10.8:1 Compression ratio

87 octane. No AFM / DFM

GM 6 Speed Automatic


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## NYH1 (Jan 10, 2009)

FredG said:


> I thought GM owned Allison, why would you team up with Furd just making them more desirable with the Allison. Should of teamed up with Dodge the Cummings and the Allison would be a bad to the bone truck.


I have no idea who owns Allison or Cummins. However, it doesn't matter, in the auto industry business is business. You build products for anyone that will buy them.

I worked for a company that was owned by Chrysler and GM. It was a weird deal. Chrysler and GM combined two major driveline component plants to form a sub-company, I guess you could call it. Chrysler owned 80% of our plant and 20% of the GM plant.

Our plant built products for Chrysler, GM, Ford and as well as imports. The GM plant built products for GM and Chrysler. Not sure who else.

The Big Three use a lot of the same parts and components suppliers ie. Dana, AAM, Borg Warner ect. The more they get out of building their own components, which they've all been doing the last 20 plus years, the more they share suppliers.

NYH1.


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