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.
Comments
Not surprising as if you check the Fuel and Emissions standards on the 3/4 and 1 ton are much less strict than the Half ton class.
Also there was no way they would make this premium required as that would be a sure way to kill sales. This is not a performance vehicle like a Corvette or CTSv that people expect to pay more for better fuel.
Wouldn’t have been on there, this is an engine for big trucks, and big trucks aren’t gonna f with that as long as they aren’t required to. Another reason that I’m glad that I can justify only having HD trucks.
Can we get an amen?! Thank you GM for ridding us of those gimmicks! Cheers.
yup AFM is a gimmick, that’s why i achieved 28 MPG in a 07 Yukon XL the other day for an 8 mile stretch in 4-cylinder mode…granted i wasn’t doing 75, but always a nice thing to see at 58 mph! Just imagine the amount of money the buyers would save over the life of the vehicle…not that it matters to them, they are already paying $20,000 too much for the vehicle in the first place. However, it better be bulletproof as it has only taken 13 years and the addition of 9/10 of a liter to lose 4 hp and gain 64 lb ft of tq over the LS6! But then again, this generation of pickups have been so astounding with fuel economy gains thus far! I am sure that we will be blown away with the progress in that department too! *eyeroll*
Comparing a Z06 Vette engine to a HD truck engine, do you know how ridiculous you sound?
It’s just an engine, dude … different characteristics.
AFM/DFM is a clever fuel savings mechanism that will get better every year – or, we could adopt the Ford strategy of small displacement engines with turbochargers …
I like V-8s with AFM/DFM myself. My 6.2 Silverado does 24 mpg at 75 mph on flat roads. I’ve gotten near 28 mpg when held to 65 mph on generally level backroads.
Just wait until a valve spring breaks & destroys the engine. AFM is a joke.
GM uses different parts on an engine for HD truck compared to the same basic engine used in a lighter vehicle. One of those things is better quality valve springs, camshaft and oil pumps. After buying hundreds of brand new GM vehicles, we knew the difference between a regular vehicle and one without a trailer pkg.
I have a 09 Silverado, the one with the afm “problem”. 190000 Mike’s and still ticking strong!
my 2014 sierra 6.2 engine had a lifter go out around 120K miles and needed to have lifters, cam shaft, timing chains, etc all replaced. 6,500 dollar repair later my engine and running again until another lifter or spring decides to break.
Geeze, I thought GM was supposed to be a Technology company per Machete Mary. They cannot even get these rudimentary features to work?
My AFM works flawlessly.
As i mentioned in my comments under other articles about the use of regular fuel to get those 464 lbs feet of torque number, this was a GM engineer speaking, so i did all the real torque and HP numbers if Super Premium gas was used and also if E85 gasoline with 95 octane was used. GM has shown the big difference in both torque and HP if E85 is used in car engines. I think it was about 511 lbs feet of torque on E85 for the 6.6 liter L8T. Remember than there are fewer BTU’s in ethanol, but the GM engine computer is programed to change the richness of the fuel mixture, so this is why you get more HP and torque.
Only if the truck has the alcohol sensor and proper A/F tables in the ECU.
I drive an 2018 with the L86 (6.2L). It is NOT flex fuel compatible. I can add the alcohol sensor easily. Just plug it into the existing harness. I would have to get a custom tune as the ECU is not setup for E85. This will void my warranty.
All American gasoline can contain up to 10 percent alcohol ) ethanol ) E85 is of course, 85 percent. The E15 fuel is about to be or has already passed U.S. government approval. Actually, i prefer the dry propane fuel which is 105 octane. The 3 different fleets that i helped manage over the years have traveled over 40 million kilometers which is 25 million miles on propane. We left the gasoline system in place and just added the LPG fuel tank, LPG fuel lines and LPG fuel injectors. The engines start on gasoline and after 2 to 3 minutes, they automatically switch over to propane. The wholesale rail car load or truck load price of propane is as low as 73 cents per gallon last week in the midwest refinery areas. It’s actually higher in Texas….LOL. Our V8 engines would travel 750,000 to 850,000 kilometers in just 5 years. That’s the same as from 469,000 to 520,000 miles. Our engines had no noticable wear, but we also ran semi-synthetic oil which also helps reduce wear. Most of the guys driving these cars, would buy them from our company at the 5 year point and give them to their wives and kids. Then they would drive them well past one million Km or 650,000 miles, with almost no oil consumption.
I was hopeing Atkinson cycle with DSF. The AFM show uneven wear with the cyinders that operate the 4 always on pistons show standard wear, and the off cylinders exhibit only partial wear. DSF would even it all out, reducing overall wear as well as saving fuel cost. Atkinson cycle i hope become standard one day
People seem to forget about one big thing.
Maybe GM opted to not include it because of reliability. Yeah sure, theses systems maybe somewhat tried and true now that they have been out for some time.
But more often than not, the more technology you add to a vehicle the less reliable it will be.
Correct me if I am wrong! But doesn’t the Ram offer cylinder shut down in their heavy duty trucks with a gas engine? If they are able to do it, I see no reason GM cannot do it successfully.
But we don’t want it.
I don’t think you understand that AFM was one the one major concern heavy duty users (and many light duty users, too) had but are now relieved with it’s absence in the 6.6. Just because they install fuel saving tech doesn’t make it good. If you are interested there are endless articles and threads about AFM technology issues. GM hasn’t been hitting too many home runs lately but leaving it off the 6.6 was a great move.
Dave,
Please list those articles and the DATES. The reason engines today can easily go over 200,000 miles is because of technology. You may not have been around when there was absolutely no emissions controls on engines, crappy oil technology, points ignition, new plugs every 10K, and the worse, leaded fuel. Also no anti lock brake and shoes for brakes, not even passenger side mirrors. I many a time had to adjust points on the side of the road, you were lucky to get 20k on tires and plenty of blow outs.
Technology will always be infused in the latest vehicles. It’s takes thousands of smalls steps to get to the perfect performance, I don’t see anytime soon that it will stop, thank goodness. Now, if they could get the Auto Stop feature to be seamless. ?
George, the 200,000 mile rating for average engine life was on the GM 496 cube, 8.1 liter truck engine. It had inconel steel exhaust valves and was rated to run on propane which burns very, very hot. GM stopped making it in the 2011 model years when GM stopped selling medium duty trucks. Of course no idiot truck user back then would use a 5W30 engine oil in a work truck unless it was a full 100 percent synthetic. It’s all about the best quality of semi-synthetic or full synthetic oils. Nobody with a brain, should use non-synthetic oil even in a small gasoline car today because the direct Injection engines of every brand build up more carbon than non-DI engines.
George S.
https://www.google.com/search?client=firefox-b-d&q=gm+afm+problems
I’ll just give you a Google link instead. More info than you can shake a stick at.
AFM is prone to certain issues and it’s fact. Technology exists to build a 30+ mpg truck but we don’t want what it would end up being so they do this instead.
Among the most popular mods on a modern pickup is overriding AFM and auto/start stop. Everything you mentioned has been drastically improved for many reasons like reliability, driveability, safety and economy. The only thing AFM does is marginally improve economy and that’s assuming you don’t use your truck as a truck.
Adding AFM to an overpowered and overweight V8 truck is backwards logic. Look at what’s happened to diesels. They have not come close to making DEF and regen long term reliable. Like AFM, it’s the band aid for regulation and what we want to drive.
If the modest savings one will see from an AFM engine is the difference between owning the truck and not I’d suggest they’d be far better off with a car.
Did GM have as much fun as Honda’s vaunted engineers?
https://settlement-claims.com/enginemisfire/CourtDocuments.html
Gawd! That close up photo of this thing is UGLY!!!
All American gasoline can contain up to 10 percent alcohol ) ethanol ) E85 is of course, 85 percent. The E15 fuel is about to be or has already passed U.S. government approval. Actually, i prefer the dry propane fuel which is 105 octane. The 3 different fleets that i helped manage over the years have traveled over 40 million kilometers which is 25 million miles. The wholesale rail car load or truck load price of propane is as low as 73 cents per gallon last week in the midwest refinery areas. Our V8 engines would travel 750,000 to 850,000 kilometers in just 5 years. That’s the same as from 469,000 to 520,000 miles. Our engines had no noticable wear, but we also ran semi-synthetic oil which also helps reduce wear. Most of the guys driving these cars, would buy them from our company at the 5 year point and give them to their wives and kids. Then they would drive them well past one million Km or 650,000 miles, with almost no oil consumption.
I think GM should be responsible for the cost of replacing the lifters that go bad because of their AFM.
My 2017 Suburban was sweet at 23mpg trips and 18.7 around the house. BUT, when you factor in at 36,800 mi the $2,300 repair bill for lifters and 2 injectors. Then again at 41,122mi we repeated the other 2 cylinders with $1,946. I said bye bye and can handle the 15mpg in my Silverado 2500 6.6 gas burner at $469 a month payment for 4yrs. I feel sorry for whomever bought the suburban. Im sure it’ll run fine for 20-30k miles then repeat my expenses. I can live without the AFM, this is GMs last chance with me before I go back to 7.4 or 8.1 old dually restoration.