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So I just bought a 2020 Silverado 2500 HD, LT Trim in Summit White, with 16K miles, ordered side steps/runners and might go from 265/70/17's to 285/70/17's one day, but thats it.
I love it, great power, tows very well with the 6 speed and 3.73 gears (did not want an 8 or 10 speed) and I don't care what folks say, I've been in a new Ram 2500 and F250, I like the feel and look of the Silverado interior/exterior, better, just my .02, although I would have been very happy with any of those. This new 2020 also has more interior room now then any other 3/4 ton, but anyways this thread is to discuss the motor.
These are direct injection, 401 cubic inch small blocks making 401 HP and 465 TQ. There is no cylinder de-activation tech, thank god.
The L8T has a forged crank and rods, and while setup for low torque and pulling, I am sure folks will want to convert it to hot rodding/drag racing configurations.
It's also a cast iron block with aluminum heads.
Here's an article on the L8T: https://www.enginelabs.com/engine-te...ers-will-love/
Sounds like with some tweaking, this could be a great engine for monster N/A builds, or supercharged builds.
Has anyone built one of these yet? Does anyone on here plan to?
Be interesting to see how they do!
I like the cubes, and I REALLY like the no AFM crap. A compression bump, cam swap and usual mods should net 450+ whp easy. 500+ on a more radical cam is there im sure. Any idea what the heads flow?
Obviously its still to new to have many floating around for grabs.
I just cant get over not wanting the 8 or 10speed and opting for the 6 speed instead.....
lol
Im not all that in love with the multi speed autos. Even the 6L80/90 im a little ehhhh over. Its that feeling of torque they lack vs a good 4spd stick or 3spd auto with a high quality stall. Theres good reason all the fast drag cars run 2spd power glides
Obviously its still to new to have many floating around for grabs.
I just cant get over not wanting the 8 or 10speed and opting for the 6 speed instead.....
lol
Jury is still out on the new ones and there are cases where they constantly search for gears, albeit I am sure thats exaggerated most of the time.
For me, I wanted proven durability with the proper gears.
GM was smart enough to match 3.73 gears with the 6L90E on this 6.6L, and it's fantastic.
Maybe I'm a little old school? Dunno but I just like knowing how reliable this setup is, even if an 8 or 10 gets a few better MPG.
Subscribed, Friday I just ordered a 2021 GMC reg cab 3500hd, 6.6gas,onyx black, x31 package,E-85 option....with options It was still cheaper than a SLE 2500.... For now I'm just doing a borla xr1 round muffler 3.5 inlet swap from factory trash can. Almost this same truck but, black grill,small mirrors,no cab lights,same wheels and multi pro tailgate.
and seat covers. But when it's out ove warranty my mind tells me TVS 2650/ headers... I hope someone can figure out some tuning solutions between now and then.
Had an older 2500HD 4x4 Xtra-cab (2004) and it had the 6.0, 4 speed auto, with 3.42's. Not the greatest MPG, but towing 6-7000Lbs. hardly knew it was there.
More motor, better gears, 6sp.... I bet that's nice.
Subscribed, Friday I just ordered a 2021 GMC reg cab 3500hd, 6.6gas,onyx black, x31 package,E-85 option....with options It was still cheaper than a SLE 2500.... For now I'm just doing a borla xr1 round muffler 3.5 inlet swap from factory trash can.
Almost this same truck but, black grill,small mirrors,no cab lights,same wheels and multi pro tailgate.
and seat covers. But when it's out ove warranty my mind tells me TVS 2650/ headers... I hope someone can figure out some tuning solutions between now and then.
Sweet truck, regular cabs are getting so uncommon, very cool. Pardon my total ignorance here regarding tuning solutions does HP or Efi live not support these new systems?
Jury is still out on the new ones and there are cases where they constantly search for gears, albeit I am sure thats exaggerated most of the time.
I have driven them all and of course if you leave it in drive and your not staying above 60mph they will certainly shift alot on hills or without a steady right foot (Even the 6speed). Most people cant figure out to pull it down a gear or 2 when not at a constant cruise speed or load.....
anyways Id LOVE to see that 6.6 with the TVS2650!!
Last edited by Ls7colorado; 03-17-2021 at 06:40 AM.
Sweet truck, regular cabs are getting so uncommon, very cool. Pardon my total ignorance here regarding tuning solutions does HP or Efi live not support these new systems?
From my understanding it's not supported right now, I've done (some) research on it and eventually it will prolly be available/ cracked. I'm not sure if it's similar too how hard it is for the c8/ or what the deal is, maybe a tuning guru could step in here and give more info on the subject. It would be much appreciated.
The problem here lately is even getting your hands on a new HD truck from GM. They can't keep any in stock here in Utah. I test drove 2 so far but not exactly what I wanted at the time. I love a diesel but the price and how the new emissions are hurting diesels in general, the new 6.6 seems like a great setup.
The problem here lately is even getting your hands on a new HD truck from GM. They can't keep any in stock here in Utah. I test drove 2 so far but not exactly what I wanted at the time. I love a diesel but the price and how the new emissions are hurting diesels in general, the new 6.6 seems like a great setup.
Diesels are great if you tow and haul a lot.
BUT....
I did the math a few years back for my type of use (daily driver, some towing) and for the approximately $10K more for the same truck in Diesel, between the MPG, fuel costs, regular maintenance, ETC...At 10 years you break even. Now this was before DEF was added into the cost also.
I overall like the L8T. It's got an interesting and ideal way of getting to 401 ci's. It uses a 10.7:1 CR like a LS3 and that might make it pretty friendly for boosting being a DI engine. (GEN3 Ecoboost is like 10.5:1 CR and 13 PSI bone stock before people turn up its bewsts) The N/A, GEN5 6.2L's use a 11.5:1 CR BTW.
Not a fan of GM neglecting to use their latest/greatest transmissions in anything but the top level trucks. Ford and Chrysler don't do this. The L8T should get a version of the ZL1's 10L90 IMO. It's stronger than the 10L80. Might be what the 10 speed Alison is based on but IDK.
I'm also not a fan of how is deliberately making the Sierra a better truck than Silverado. Normally I would careless whether I had a Silverado or Sierra, bur with how GM decided to make them look so different now you have to care. I seem to be one of the few who really like the look of the new Silverado, but I'm not of fan of the new Sierra and it's weird shaped wheelwells and foglight cutouts. But Sierra gets a bunch of little things that add up to it being a better truck. Sierra gets unlock buttons on all 4 door handles instead just the fronts like the Chevy. Sierra gets a power passenger seat unlike Silverado. Sierra gets rear seat climate controls where Silverado doesn't. Sierra 1500 can be had with the awesome CarbonPro bed and Silverado can't get it, but at least Silverado can now be optioned with the MultiPro tailgate. AT4 1500 can be had with the 3L Duramax, but that's not an option on the Trail Boss. Just a lot of little things that add up to the Sierra being better overall for not much extra $, but it's like why is GM doing that to their volume selling truck? It's not like mid to high $60K to $70K Silverado LTZ's and High Country's should get rear seat ventilation controls, or a power passenger seat, or a fancy CarbonPro bed, or unlock buttons on all doors. Can higherend Silverados even get rear heated seats like the higher time Sierras get? Again comparable Sierra models are only a few hundred more than the Silverado, but they get a bunch of little things that in a $55K+ truck the Silverado needs to have. And give us a RCSB offering in the 1500.
I will say that I think that Ford new 7.3L Godzilla engine is going to have huge potential with its 4.22" bore diameter. It's pretty sad and funny how all the internet Ford fanboys use to say things like, "LS engines are inefficient, outdate, POS pushrod having dinosaurs," but now that Ford has come out with their new OHV engine they want to get all excited, and jump on that bandwagon.
BTW if you post this in the GEN V section, it may lead to a better, or more interesting discussion from people more interested in the GEN engines.
Not a fan of GM neglecting to use their latest/greatest transmissions in anything but the top level trucks. Ford and Chrysler don't do this. The L8T should get a version of the ZL1's 10L90 IMO. It's stronger than the 10L80. Might be what the 10 speed Alison is based on but IDK.
Not everyone wants an 8 or 10 speed, they can constantly hunt for gears and the jury is still out on their longevity.
With 3.73's and a 6 speed (with the manual option to put it in any gear you want) its probably the most durable, reliable setup money can buy and it works great for most applications.
Although I agree, consumers should get the option of the 8/10 speed with the L8T, which I bet will be an option soon. But I'd rather have the 6L90, just my .02.
Originally Posted by JROC
I'm also not a fan of how is deliberately making the Sierra a better truck than Silverado.
In terms of what you get for the money, yes, the Elevation for example is a great bargain package.
Chevy charges a premium amount for their trims, and they should come with more features for what you pay.
In that regard I agree, in terms of build quality, dependability, they are the same.
Originally Posted by JROC
I will say that I think that Ford new 7.3L Godzilla engine is going to have huge potential with its 4.22" bore diameter. It's pretty sad and funny how all the internet Ford fanboys use to say things like, "LS engines are inefficient, outdate, POS pushrod having dinosaurs," but now that Ford has come out with their new OHV engine they want to get all excited, and jump on that bandwagon.
There's been alot of comparison tests done and the 6.6L pulls just as much as the 7.3L, and in some cases get's better mileage.
It's also stronger and more efficient then the 392, both are great options though.
Im a GMC truck guy always have been but I gotta agree the Silverado looks better than those fugly wells on the GMC this time round. They are growing on me but only on the higher riding models or lifted trucks. On the low ride Denalis the wells look like a mistake.
03-15-2021, 11:27 AM
Lets Talk GM's New 6.6L L8T Engine 
