General Motors is planning on updating the powertrains for the Chevy Silverado HD and GMC Sierra HD, GM Authority has learned from sources familiar with the matter.
The upcoming powertrain updates will be made to Chevy Silverado HD and GMC Sierra HD models equipped with both the atmospheric 6.6L V8 L8T gasoline engine and the 6.6L V8 L5P turbodiesel Duramax.
The updates will likely be applied with the upcoming Chevy Silverado HD and GMC Sierra HD model refresh / mid-cycle enhancement, currently expected to arrive for the 2023 model year. However, it should be noted that there are rumors that Chevy Silverado HD and GMC Sierra HD model refresh could be pushed back to the 2024 model year.
When equipped with the 6.6L V8 L8T gasoline engine, the current Chevy Silverado HD and GMC Sierra HD are rated at 401 horsepower at 5,200 rpm and 464 pound-feet of torque at 4,000 rpm. When equipped with the 6.6L V8 L5P turbodiesel Duramax, output is rated at 445 horsepower at 2,800 rpm and 910 pound-feet of torque at 1,600 rpm. The gasoline engine mates to a six-speed automatic transmission, while the diesel engine mates to a 10-speed automatic transmission.
For reference, we’ve included a list of the four heavy-duty trucks currently on the market, including both GM trucks and their rivals, as well as their respective powertrains and output figures:
| Vehicle | Engine | Fuel Type | Aspiration | Valvetrain | Horsepower (hp @ rpm) | Torque (lb-ft @ rpm) |
|---|---|---|---|---|---|---|
| 2021 Chevy Silverado HD | 6.6L L8T V8 | Gasoline | Atmospheric | OHV 16-valve | 401 @ 5,200 | 464 @ 4,000 |
| 2021 Chevy Silverado HD | 6.6L Duramax L5P V8 | Diesel | Turbocharged | OHV 32-valve | 445 @ 2,800 | 910 @ 1,600 |
| 2021 Ford Super Duty | 6.2L Boss V8 | Gasoline | Atmospheric | SOHC 16-valve | 385 @ 5,750 | 430 @ 3,800 |
| 2021 Ford Super Duty | 7.3L Godzilla V8 | Gasoline | Atmospheric | OHV 16-valve | 430 @ 5,500 | 475 @ 4,000 |
| 2021 Ford Super Duty | 6.7L Power Stroke Scorpion V8 | Diesel | Turbocharged | DOHC 32-valve | 475 @ 2,800 | 1,050 @ 1,600 |
| 2021 GMC Sierra HD | 6.6L L8T V8 | Gasoline | Atmospheric | OHV 16-valve | 401 @ 5,200 | 464 @ 4,000 |
| 2021 GMC Sierra HD | 6.6L Duramax L5P V8 | Diesel | Turbocharged | OHV 32-valve | 445 @ 2,800 | 910 @ 1,600 |
| 2021 Ram HD | 6.4L HEMI V8 | Gasoline | Atmospheric | OHV 16-valve | 410 @ 5,600 | 429 @ 4,000 |
| 2021 Ram HD | 6.7L Cummins I6 | Diesel | Turbocharged | OHV 24-valve | 370 @ 2,800 | 850 @ 1,700 |
| 2021 Ram HD | 6.7L Cummins I6 HO | Diesel | Turbocharged | OHV 24-valve | 420 @ 2,800 | 1,075 @ 1,800 |
It’s also worth mentioning that Ford is rumored to be working on a twin-turbo version of its 7.3L V8 Godzilla gasoline engine. Make sure to check out the full story from our sister publication, Ford Authority.
The refreshed Chevy Silverado HD and GMC Sierra HD will follow model refreshes / mid-cycle enhancements for the Light Duty Chevy Silverado 1500 and GMC Sierra 1500, slated to debut with the upcoming 2022 model year.
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Comments
they need to bring back the 4;10 rear end with the 6.6l motor
My 2021 HD gas has the 4:10 axle which was the only choice
No it doesn’t. Only “choices” available are, 3.42 for the 6.6 l5p Duramax and 3.73 for the 6.6 L8T gas. The 4.10 is NOT an option on any 3/4 or 1ton truck from GM. The only trucks from GM that has the option for a 4.10 is the medium duty 4500, 5500, 6500 Silverado trucks.
Your sadly mistaken my friend 4:10 is standard on the gas engines
Wrong for a second time….
no 4:10 . 3:73 is the only ratio available for 6.6 gasser
Your right I’m wrong I was looking at the wrong truck sheet ,I did review my 2021 HD specs and now seeing just the 3;73 ratio is the only choice . My Bad
I think the dealer lied to you
Cool man,how about a 502 big block back in the fold too? Last hurrah for the big block?
The last hurrah for the big block was 2006.
True real josh, and I don’t think we will truly see the return of the true “big block” as the main difference between small blocks and big blocks was all the additional cooling passages afforded by the larger bore spacing. Modern engines are just so efficient that they don’t require that much cooling. We may see the new half tons use an electric water pump so it can be shut off in low loads. We don’t need big blocks for all day hard work.
But that doesn’t mean big displacement “small blocks” aren’t in the works. There is still a rumor of GM working on a 8L “small block” I’d rather see the VVL tech used in the 2.5 and 2.7turbo, as it will also give an increase in power and efficiency added to the 6.6 gasser.
One dislike from fake Josh lol. Tbh, I was just kidding, I realize there is more than one Josh in the world. Btw, I wonder if this other Josh made it to the Josh fight in Kansas or Nebraska or wherever it was…
same with jakes bro
If GM brings back a competitive big block AND gives this truck a much needed face-lift (that’s not ugly like it is now) I’m in!
GM’s top management team does not ever put the gas mileage rating in their memo, with gas prices these days, MPG is the top priority in the decision-making of what you buy now. My 12-year-old Silverado gets the same MPG as the new trucks. This is a shame and disgrace.
Oh please. Does your 12-year-old Silverado also have “the same” levels of power and torque as the current ones? Does it also have “the same” levels of towing or hauling capability? Of course it does not. It’s inferior in all of those areas.
The point is that, over the past decade, fuel economy has improved, but so have power, torque, trailering and hauling. Vehicles (trucks included) have become safer, more comfortable, and more feature-rich. Think about that next time you do a head to head comparison… in your head.
Right Alex. My dad’s first Silverado was a 2001, with the 5.3 vortec. Rated to tow 6700 lbs, 288 tq. Got 18 mpg highway. Mine is currently a 2009 Silverado getting 19 mpg highway and makes 335 HP, tows 7900lbs. A new colorado with the 3.6 (about to be replaced with the 2.7 turbo) tows 7700 lbs, 280 tq and 310 HP, and makes 26 mpg highway. It’s also larger than my dad’s first truck. I was looking at an HD before the chip shortage but depending on how the 2022 half ton upgrades go, I might go half ton. I need to tow up to12200 lbs, as I got an aluminum horse trailer for a steal and can only tow it half loaded right now, but by the time you optioned a half ton with the max tow package, an HD was significantly cheaper.
12k is too much weight for any half ton if you are going to be pulling it even semi-regularly.
Dwight Morgan, I cant decide if your just dumb or jealous maybe both but your 12 yr old worn out truck doesn’t stand a chance against the new ones. I’ve owned many gm trucks to include a 2019 Silverado 1500 and a 2021 Silverado 2500HD Duramax and the new ones will easily out do the previous gen trucks as they should. and FYI if MPG is your biggest concern when buying a truck maybe you should just go buy a Honda Ridgeline. Assuming you could.
Don’t trash talk on what you don’t know about. Try owning a brand new truck before you say stupid things.
No way if it is a diesel, the 2020 GMC 2500 HD Denali is the most efficient in highway fuel economy yet, and the heaviest, which goes against logic, but I am witness, its my first truck that regularly pulls over 20 mpg, highway, My 2011 was 375 lbs lighter but averaged only 18 or so mpg highway.
Well this is interesting…
There has been almost zero rumors about any powertrain updates since the 10 speed Allison, and the 6.6 Gas.
Almost makes you wonder where they have the ability to even upgrade. 10 speed gas I could see.
The 7.3 Ford seems popular, but I feel a proper big block would be unlikely. (even though incredibly welcome)
As ludicrous as it sounds, I’m convinced a turbo big block direct injection engine could deliver similar performance and economy as the diesel.
6.6L gas + 10 speed makes sense to replace the 6-speed.
Power and torque improvements to L5P make sense.
Big block? Fugget about it.
GM needs to get out in front of the media’s love affair with the electric F-150. That’s it.
My youngest son just purchased a new GMC truck in January on Mother’s day it develop a knock in engine and was towed to dealership in Eden and has been their over two weeks with no response. Kinda tough for a new purchase and making payments for NEW TRUCK in shop .
It happens sometimes… very rare though to see a new truck eat the engine.
That’s why manufacturer warranties exist. He should be driving a comparable loaner that meets his needs. It sucks and definitely leaves a negative impression. Anecdotal stories on the internet are tough because for every one person who has an issue there are hundres or thousands with zero issues. I bought a 2018 Silverado LT with the 5.3L and have had ZERO issues with it for 3 years and 30,000 miles. Oil changes and tire rotations.
alright guys, I keep reading all the comments. Should I buy 2021 hd 4/3 ton or wait for the 2022?
Good luck finding a 2500HD right now. They are very tough to come by.
I just sold my 2017 2500 LTZ duramax and bought a 3500 LTZ duramax. WOW what a difference of a truck in Generations. The 10 speed is amazing. i cant feel the shifts like the old 6 speed. just order a 2022 now. Order books are closed for 2021 and nothing on the lots thats not sold already.
It is weird, I put a post up about GM and GM authority chart on the powertrain. Go back look at the chart nothing on MPG. I stated that GM should also put its MPG in these charts. With gas prices now back over $3.00 a gallon that the MPG is a big deciding factor on auto purchases. I also stated I have a 12-year-old Silverado and my 12-year-old truck gets about the same combine MPG as the new trucks GM build today. I stated that GM management and engineering stop the effort of improving MPG, and this is a shame. I got a lot of thumb-down reactions, don”t know why I am only stating the truth, and I am a Silverado owner. With new transmissions and all the new technologies today, I believe the MPG should have improved more than it has over the last 12 years. I am ready to purchase a new truck, and I think a new truck should be getting better combine MPG than my 12 year old
MPG and efficiency has improved drastically. What class truck do you drive? If it’s a 1500, compare the specs of you truck to the new colorado. They get 26 mpg. If it’s a 2500, look at a 1500 with the 5.3 and max trailer package. Same stats power/ and capability but gets 22mpg, not 14. The real difference with the fuel consumption war is that trucks are getting so much more capable and the efficiency increases in the motors are being eaten up by the additional frame/body size….. But you also can now go down a truck class and get massive fuel savings for no Compromise in capability
The most heartbreaking line in the entire article was the rumor the HD refresh could get pushed back to ‘24.
GM should offer more engines.
Offer the 3.0 I6 for customer that need a big truck for hauling big, but not necessarily heavy items.
Offer another gas powertrain, maybe something like the 6.2 as well.
The point of the 6.6 gasser is reliability. Some people don’t care about that as much, and MPG may be a bigger concern.
If you aren’t hauling heavy loads just get a longbox light duty.
The timeline works for me. I’m thinking about trading up my 2015 Heavy Duty in 2025. Hopefully the interior upgrade of the Heavy Duty includes a nice twelve-inch flat-screen display. If it includes some electric powertrain parts, that cool too! However, it would be great if the new truck is software editable with something like HP Tuners software.
I expect to be disappointed…with the “powertrain upgrade” to the gas engine being a switch from the 6 speed auto to the 10 speed. Yes, that’s a respectable upgrade, but it should be accompanied by power and torque increases, too. I never understood why they created a unique crank for this engine; upgrade it to LS7 dimensions (4.00″ stroke) and the engine grows to 6.8 liters, with an even greater emphasis on torque – really low hanging fruit stuff.
The D-Max has to cross the 1,000 ft lbs threshold to remain viable (on paper). At <1,000, it's too easy of a target for Powerstroke and Cummins salesmen, despite the fact it handily outperforms the Ram in the real world.
Going back to 3.73 gear on Duramax and have 4.10 available on 6.6 gas should be the first place to start with the upgrades.
There is zero reason to go back to a 3.73 with the D-Max when it’s backed by the 10 speed. With the old (Allison) 6-speed, first gear (3.10:1) produced a “net effective” first gear ratio of 11.56:1 (3.1 x 3.73). But the 10-speed has a 4.54:1 first gear, resulting in a net effective ratio of 15.53 (4.54 x 3.42). If you put a 3.73 behind the 10 speed, it would be the equivalent of a 5.00 axle ratio behind the old 6-speed – pointless.
The numbers are similar with the gas engine, but the spread isn’t as big…10-speed & 3.73 is equal to 6-speed (6L90) and a 4.35 axle. I agree they shouldn’t have dropped the 4.10 while sticking with the 6-speed, but no point in going back to a 4.10 if they simply upgrade the transmission to the 10-speed – which should have happened when they introduced the 6.6 gas.
Part of the higher gear ratios is a larger/stronger/more efficient input gear. They have already increased the sun gear ring size as well. The reduction is done in the tranny. These higher ratio differentials are way better and have no interchangeable parts with the old 3.73 and 3.42 diffs they replaced.
It´s time for GMC to follow the other two Ford and Ram by using modern Compacted Graphite Iron( CGI) in the blocks. This is a must when they will acceive +500 hp and a class leading torque. The blocks will be made at Tupy Foundry in Brazil and sent to Brooksville for machining.