2017 GMC Sierra HDs Gain Power With New Duramax

2017_GMC_HD_Dually_A17_1351[3] II

By Bruce W. Smith

Towing a 26-foot, 9,600-pound Jayco Eagle HT fifth-wheel trailer up the twisting 8 percent grade between Paradox and Telluride, Colo., can put a strain on a pickup truck as the elevation closes in on 10,000 feet. But behind the wheel of the 2017 GMC Sierra 3500 Denali dually I recently drove, the travel trailer barely affected driving performance, requiring little more than a light touch of throttle to maintain speed.

The all-new 6.6-liter LP5 Duramax turbo-diesel under the Sierra Denali 3500 hood is one of the strongest engines on the road in a heavy-duty pickup, with a factory rating of 445 horsepower (tops in its class) and 910 pounds-feet of torque (second place in its class). Combined with a well-appointed interior and sound levels rivaling a library, GM's marquee full-size heavy-duty pickup should be on the radar of anyone who tows big trailers long distances.

"The typical Denali buyer is a self-made individual that is a disciplined achiever, highly organized, with high standards," said GMC Marketing Manager Stu Pierce. "They typically tow big trailers in both their business profession and as part of their personal lifestyle, all of which is what attracts them to GMC Sierra Denali HDs."

The Denali trim level is undeniably the flagship of the GM heavy-duty pickup lineup when it comes to style and luxury, but it's the new 6.6-liter V-8 Duramax LP5 diesel engine that will be the attention grabber for anyone thinking of stepping into a one of GM's 2017 HDs, be it a GMC or a Chevrolet at any trim level.

Inside the Duramax LP5

While little has changed structurally with the 2017 HD pickups, including their appearance, the changes to the hood and what lies beneath the diesel are significant. The new hood sports a multistage air-induction hood scoop that now provides more than 50 percent of the air to the LP5's intake, supplementing the previous generation's intake located in the fender well (as before). The induction system provides the coolest air source into the charge air cooler, which is especially helpful during the summer.

That supply of fresh, cool air dumps into a new BorgWarner turbo that flows more air than the outgoing, less powerful LML Duramax. In fact, in addition to the new turbo, 90 percent of the parts on the LP5 are also new. The only common part shared between the two turbo-diesel engines is the 90-degree V-8 block.

The LP5 turbo-diesel has new heads, valve-train parts, rods, pistons, camshafts, crank, turbo and injectors. They combine to give this latest-generation Duramax 19 percent more torque (910 pounds-feet compared with 765) and 12 percent more hp (445 versus 397) than the previous engine. The new engine delivers 90 percent of its peak torque by 1,500 rpm.

According to Eric Stanczak, vehicle chief engineer of GM full-size trucks and SUVs, who accompanied me on that Colorado drive, the LP5's heads flow 20 percent more air, the internal sealing is tighter, the rods are stronger and the forged crankshaft has larger journals. This combination of upgrades allowed GM to bumped up the cylinder pressure 20 percent higher than the LML.

2017 Duramax Emblem Hood IMG_6457[5] II

Another upgrade that has a significant performance impact is the LP5's use of aluminum pistons that have bowl rims "remelted," which is a strengthening process similar to what's used to harden steel. Stanczak said GM is the first automaker to use this technology in a full-size pickup engine, which should help limit or prevent "thermal-cycle fatigue," a failure commonly seen as hairline cracks radiating out from the center of the piston after heavy use, caused by the ever-changing temperatures inside the combustion chamber under repeated high-load, high-stress, high exhaust gas temperature situations such as towing.

Change in Fuel Delivery

The LP5 received another big change: It now uses solenoid-activated injectors instead of the earlier piezo type. Tom Dye, the lead development engineer for GM HD pickups, said going to solenoid-activated injectors allowed engineers to fine-tune the LP5's overall performance in many different situations.

Dye said the computer controlling the injection system can activate as many as "seven distinct injections in a cylinder during a single combustion event, allowing fuel to be delivered at precise timing and amounts depending on the engine load and operating conditions."

There have been changes getting the fuel to the high-pressure fuel pump and how the turbo is used. The new engine now employs a low-pressure electric lift pump to prime the fuel system faster, and the BorgWarner turbo has a newly refined variable-vane system to help increase engine exhaust braking in different stages. The turbo system can now deliver 75 to 180 brake hp between 1,600 and 2,800 rpm, according to Dye.

The LP5 also employs a dedicated turbo oil circuit separate from that of the engine, which is specifically designed to keep the bearings cooler, improving long-term durability. On the downstream side to better reduce emissions, the diesel oxidizer catalyst has been relocated from the truck's exhaust that runs under the floor so that it now connects at the turbo. Dye said this change was done to provide the maximum heat in the shortest amount of time to the catalytic converter, firing off the catalysts, which lowers nitrogen oxide and hydrocarbon emissions, making the LP5 the cleanest and most environmentally friendly diesel GM has ever produced.

Speaking of emissions, GM said the 2017 HDs' selective catalytic reduction system has been improved, reducing the number of regens per tank. It now uses a 7-gallon diesel exhaust fluid tank, replacing the smaller 5.3-gallon tank and giving owners more miles between fill-ups. Unfortunately, GM continues to locate the DEF tank under the floor of the front passengers, making it quite exposed to underbody damage. Thankfully, it remains well insulated.

More Downstream Upgrades

2017 GM LP5 Illustration[3] II

In addition to the engine changes, the Allison 1000 transmission received a few changes in its solenoid control pack so it would continue to respond seamlessly and handle the extra power and performance increases from the new engine. For example, the six-speed automatic now provides the driver with three separate modes of grade braking: Manual, Tow/Haul and Cruise Control, each of which has a unique set of parameters and capabilities.

We saw the direct results of those improvements during our drive event, with near instant cold starts and the strong exhaust braking coming down several steeper grades (one as much as 8 percent) where we never had to touch the brakes during our descent. Both the transmission and software upgrades are big improvements over the 2016 Duramax powertrain.

Bumping up torque by 145 pounds-feet and hp by 48 also necessitated a couple of upgrades in the drivetrain to ensure long-term reliability under demanding conditions. Those upgrades include stronger and thicker drive shafts for both the 2500 and 3500 models, and the use of bigger Dana Spicer 1485 series universal joints to hold it all together. Model-year 2016s used the Spicer 1410s.

From new hood technology to stronger U-joints, the 6.6-liter V-8 LP5 Duramax/Allison 1000 combo in the 2017 GM HD pickups will make them a force to reckon with in the towing world. Moreover, the luxury level of the GMC Denali trim wraps all the new-found power and performance in refined elegance. While we know pricing for these trucks pushes $70,000, the upgrades and improvements make a strong value case at this level — especially if you've got a big trailer and a lot of miles in your future.

We'll have more to say about this new Duramax in May when we roll out our 2017 3/4-Ton Premium Truck Challenge. For that competition we brought together four crew-cab 4x4 luxury-level diesel pickups for a head-to-head competition in scores of categories. We'll have more to tell you in the coming weeks.

Cars.com photos by Bruce W. Smith

 

2017_GMC_HD_Dually_A17_1369[3] IIThe 2017 GMC Sierra 3500 Denali dually is rated to tow up to 23,200 pounds when equipped with a gooseneck/fifth-wheel hitch. GMC only offers one axle ratio with the 6.6-liter Duramax V-8 turbodiesel: a 3.73:1 gear with an auto-locking limited-slip rear differential.

 

2017 GMC Denali 2500 ATV Trailer[3] IIGeneral Motors no longer requires the use of a weight-distributing/weight-equalizing hitch when towing trailers "on-the-ball" up to the 2017 HDs' maximum 14,500-pound weight-carrying capacity. We were told that's because of the way the receiver hitch is attached to the frame; the front receiver attachment point on the frame is almost to the rear axle, allowing it to achieve similar results to what a typical weight-distributing hitch can accomplish.

 

2017_GMC_HD_Dually_A17_1364[5] IIGM's LP5 turbo-diesel has new heads, valve train, rods, pistons, camshafts, crank, turbo and injectors, all combined to give this latest-generation Duramax 19 percent more torque (910 pounds-feet versus 765) and 12 percent more horsepower (445 versus 397) than the LML it replaces. The new engine delivers 90 percent of its peak torque by 1,500 rpm.

 

 

Comments

These are still aimed at the recreation crowd. If you want to operate a commercial fleet or use it for serious work, the Super Duty has you covered.

We just got one of these at work and that DEF tank is horrible looking hanging under the truck. It looks like an after thought.

Great looking truck with class leading horepower, what more could you want? Plus it always beats Ford in the truck challenges!

Sweet truck GM, maybe one day Trash Motor Company will be able to build something as nice.

@papajim,
This will not be my next truck.

This is bound to stir the hornets nest ;)

Towing with a truck like this is nice.

But if anyone has traveled to the US you will see that most pickups haul air with one passenger, not tow trailers, with 3 abreast in the rear.

From the comments on PUTC you would think if you were an overseas reader you would assume that the US is full of pickups towing trailers.

This just ain't the case, but we need more regulation in the US against trucks like this. Because those who are towing trailers need to be regulated so they stay within the law.


I doubt that this Sierra's suspension will hold up if someone actually utilizes the weight rating. This is just a fact.

That's the best HD truck on the market. Packed with technology like Duramax engines and Allison transmissions. This will be the last truck you will ever need to purchase.

Great looking truck with class leading horepower, what more could you want? Plus it always beats Ford in the truck challenges!


Posted by: TruckKing | Feb 27, 2017 11:30:28 AM

It will still fall short behind the Leader. It's already been tested.

http://www.tfltruck.com/2017/02/early-access-dually-duel-2017-chevy-silverado-hd-vs-2017-ford-f-350-vs-2017-ram-hd-video/

That's the best HD truck on the market. Packed with technology like Duramax engines and Allison transmissions. This will be the last truck you will ever need to purchase.


Posted by: GMSRGREAT | Feb 27, 2017 11:53:34 AM

That's because this junk will kill you.

The GMC Sierra with the mesh grilel has to be one of the ugliest trucks on the road today.

But anyway did you see what GM has been doing? GM boosted incentives in February. They scared now!

https://twitter.com/mrlevine/status/836189222969180160

Many of us Ford "losers" started out as Chevy guys. But we then tried Ford and found out why Ford has the best built, best selling trucks and we will never go back to Chevy/GM.

Many of us Ford "losers" started out as Chevy guys. But we then tried Ford and found out why Ford has the best built, best selling trucks and we will never go back to Chevy/GM.

Posted by: Dave | Feb 27, 2017 12:17:12 PM

You can't compare the purchase of a 15 year old 200,000 mile chevy as your first vehicle to the "I fell for a Ford marketing ad" new Ford.

Congrats to Ford for winning 3 of 4 major races at Daytona.

http://www.autonews.com/article/20160304/OEM11/160309909?template=mobile

Wow, NHTSA involved, another Ford cover-up exposed.

the twins seems to be happy with second place, this is a bad business model to go by, copying others but not striving to be the leader seems to be the twins new slogan.....

Isn't that GM junk the truck that got its butt kicked by a superduty with less HP and heavier. Hahaha

Injectors on all these new diesel engines are the weak link.
I went through 2 sets of injectors during the 298K I owned my Duramax. That's an unexceptable expense which I why I'm back to burning gasoline/E-85.

This is how GM engineers spend thier time, then there's the Ford dumb dumbs spending all thier time trying to figure out how to get V8 sounds blare out of the speakers.!!! LOL
I know which one I'd rather have.

LOL! When are these people gonna learn that a truck is more than just the # of cameras or buttons up and down the center of the dash, both sides of the steering column, all over the door panels, etc etc,etc.


Posted by: GMSRGREAT | Feb 27, 2017 1:53:50 PM

Heck even GM can't even get that right. One day they will after Ford comes out with something newer and better.

@Jeff S. and @Papajim
"Towing a 26-foot, 9,600-pound Jayco Eagle HT fifth-wheel trailer up the twisting 8 percent grade between Paradox and Telluride, Colo."
That 5th Wheeler is not exactly huge or heavy.Going by the characteristics of the Denali, it should not be an issue at all

Wow, NHTSA involved, another Ford cover-up exposed.


Posted by: Sierra | Feb 27, 2017 12:42:59 PM

Just like your sierra your link don't work. Good thing I am able to get into the properties from the source of the link (your phone) and get it. Nice old article hahaha

Jeff S.

You sound like a tree hugger that got lost and can't find his way home.

But if anyone has traveled to the US you will see that most pickups haul air with one passenger, not tow trailers, with 3 abreast in the rear."
And your point is?

"From the comments on PUTC you would think if you were an overseas reader you would assume that the US is full of pickups towing trailers."
So?

"This just ain't the case, but we need more regulation in the US against trucks like this. Because those who are towing trailers need to be regulated so they stay within the law."
So because the trucks are not currently illegal you want stricter laws so that they stay within the law?????


"I doubt that this Sierra's suspension will hold up if someone actually utilizes the weight rating. This is just a fact."
Is it a fact that the suspension won't hold up or that you doubt something with no facts to back up your statement?

Boy with todays news on GM having hard time trying to sell any trucks, all those stupid truck commercials not even working.
News headlines from link posted above:
"GM Dials Up Profit-Sapping Pickup Discounts as Rivals Gain "

"GM spent 26 percent more in discounts on each Silverado truck than Fiat Chrysler paid per Ram and 85 percent more than Ford allocated for F-Series, according to the Power Information Network data, which J.D. Power doesn’t release to the public."

Ouch...

Junk!!!!!

"General Motors no longer requires the use of a weight-distributing/weight-equalizing hitch when towing trailers "on-the-ball" up to the 2017 HDs' maximum 14,500-pound weight-carrying capacity. We were told that's because of the way the receiver hitch is attached to the frame; the front receiver attachment point on the frame is almost to the rear axle, allowing it to achieve similar results to what a typical weight-distributing hitch can accomplish."

Mark, you should be embarrassed to have printed this. No, I am not challenging the rating but the statement explaining the rating is rediculous. A weight distributing hitch works by using the torsion bars to create a torque moment about the ball that forces the front of the truck down and lifts the rear. It also transfers some of the weight back to trailer axles. When setting up a weight distributing hitch you adjust the weight transfer by choosing torsion bars appropriate for the load and then fine tuning the tension on the bars, not by moving bolts holding the hitch to the truck.

If you want to verify this put a trailer on any other truck with a weight distributing hitch and document what happens to the height front and rear when you drop the trailer on the ball and again when you tighten the torsion bars. Then document what happens when you hook the same trailer to a 2017 GM truck. I am sure that you will see a difference.

What a beast. Guessing it's going to be the #1 rated truck for overall towing. Fords are nice but GM's are just more refined.

Jeff S.

I am still marveling at this statement:

"From the comments on PUTC you would think if you were an overseas reader you would assume that the US is full of pickups towing trailers."

What DID you expect to find on PICKUPTRUCKS.COM?, bicycles?

Pushing 445HP and over 900flbs will definitely get the job done in a pickup truck ,but longevity and resale value can't hold with the diesel manufacturing experts like Cat and Cummins.
I wished Cat would have designed a small pickup truck engine for the US market and hooked up with Ram or Ford or even Toyota/Nissan.
I run a small fleet of Class 8s with C-15 acerts converted back to single turbo straight pipes and they are a BEAST at 550HP and 1900flbs backed with 18pds . Nothing better than a cat diesel when taken care of. A couple of my trucks are pushing 1.4mil on the dial having never been cracked open and purring like a kitten with better than average oil samples and blowby.
I guess I'll have to settle with a Cummins the second best diesel on the market instead of the best, I just can't decide weather to wait and see what the new Frontier offers or go ahead and buy a Ram 1500.
(hate the looks of the Titan)

@Walt: This isn't rocket science what GM is doing with their trailering hitches. The trailer tongue weight is carried through the hitch mounting points to the frame. Placing the mounting points further towards the front of the truck transfers more of the weight there.

Coming in second is not bad, better than being third,however not as good as First which is justifiably reserved for the mighty Ford Super Duty!
This may be the only bright spot for General Malaise this year. 2017 is going to be rough and 2018 even worse.

I hear that this truck includes the GM tone-technology that allows passengers to hear a slightly different engine sound. You just roll down the window and hear the beautiful sounds of a real engine....not some V6 popcorn fart!

Not to be outdone here a Ford engineer testing their new tone-technology....

https://www.youtube.com/watch?v=w9YluPOyXmg

IMPRESSIVE!

More bad news for shaky GOVT motors...geez :-(

http://www.msn.com/en-us/money/companies/gm-dials-up-profit-sapping-pickup-discounts-as-rivals-gain/ar-AAnxer6?li=AA4Zjn&ocid=spartandhp

Interested to see how this will affect Feb sales but for sure if will be another Ford sweeping win; one brand truck trumping shaky GOVT motors 2 brands with 2 trucks each strategy...now that's IMPRESSIVE!...HELL YEAH!!!!

@Lionel - Oh I think it will balance out with this Lionel....lol

http://fordauthority.com/2017/02/ford-focus-c-max-structural-integrity-welding-apron-joints-recall/

and this...

https://qz.com/901046/ford-recalls-exploding-kuga-suv-in-south-africa/

and this...

http://www.equipmentworld.com/ford-recalls-2017-f-150-for-instrument-panel-bug-affecting-gear-indicator/

But no worries...the crack Ford engineers are perfecting that tone-technology....

https://www.youtube.com/watch?v=iQNFTkR9cc0

Good work Ford!

@Walt: This isn't rocket science what GM is doing with their trailering hitches. The trailer tongue weight is carried through the hitch mounting points to the frame. Placing the mounting points further towards the front of the truck transfers more of the weight there.

You are correct that it is not rocket science, in fact it is not science at all. Moving the bolts does nothing, the load has to be moved. That is why goose-neck trailers and load-distributing hitches with torsion bars exist. You could bolt the hitch to the front bumper but unless the ball is moved or there is some method of transferring the torque all that is accomplished is taking some stress off of the back end of the frame. As I said earlier, try it both ways, take good measurements and you will see. One test is worth a thousand opinions.

Great point Lionel....I mean companies like Ford spend real money developing"tone-Technology".....

https://www.youtube.com/watch?v=YBx4J2HAwg8

How is it that you have the horsepower and torque numbers up but the tow number or low still

Lionel chevy will be in 3rd. I just hoped by the local ram dealer. Quad cab 4wd 5.7 hemi $27k. All 17 1500 trucks are $13k off.

hopped

How is it that you have the horsepower and torque numbers up but the tow number or low still
Posted by: Earl | Feb 27, 2017 8:59:21 PM

Because its about point less to have a 30,000 pound tow rating on a 1 ton truck. It's only amounts to like 3% of HD buyers a year. Seems most people at that point just buy the beefier medium duty trucks for bout the same price. Around 2:14 mark in the video below they talk bout it. Also something to think about 3 years from, now all new trucks will be out. No sense in wasting money to reengineer the current 2011 frame with all new one coming soon for only 3% of the market. That's my take on it anyways.

https://www.youtube.com/watch?v=AtY2AiLNHPk
https://www.youtube.com/watch?v=AtY2AiLNHPk

Here in Pennsylvania there are construction crews building pipelines and the crews all use HD Ram Trucks.
They hammer and abuse these trucks by taking them to extreme off-road conditions, towing giant generators, steel pipe and earthmoving equip.
When I see how well those Ram HD's perform I can't help but being impressed.
My friend Donny (who's a Chevy Guy) says they only use Ram HD Trucks cause they cost less and are lowest price on a bid process.

If it was me and I needed a HD Truck I would own a Ram HD

AHAHA! Love how even on a GM article, GMS, Johnny and some others that post different names have to continue to defend the twins due to their second place showing, and under powered diesels, that also place them behind the leader FORD!

Posted by: Nitro | Feb 28, 2017 7:48:04 AM

Nitro your wife has been trying to reach you. The service dept called and said your Superduty is ready to be picked up......again.
Now, go....go,go,go and get out of here.

I like what GM has done by bumping up their 1/2 ton max tow rating to 12,500 lbs knowing full well that their platform can do it safely and confidently. Ford hasn't responded. LOL!

http://news.pickuptrucks.com/2016/01/whats-the-best-light-duty-truck-for-towing-2016-texas-truck-showdown.html

Sure is alot of GMS replies on here continuing to have to defend the twins, wonder why that is????
Posted by: Nitro | Feb 28, 2017 11:28:05 AM

They're scared.
Posted by: Frank | Feb 28, 2017 3:22:26 PM

How is that scared or defending? It's facts with links. Truth is Ford is scared, low profits with the newest trucks, and lowest retail buyers. Only their specialized truck beats 2014 GM numbers. Their everyday F150 gets body damage from a shoe box in the bed and car wash. Timing chains flop out faster then loose tire chains. Tied with the under dog Ram in 3 yr dependability in JD Powers. Ford is a joke and has been, thank Alan Mulally and Mark Fields for the failure.

I like what GM has done by bumping up their 1/2 ton max tow rating to 12,500 lbs knowing full well that their platform can do it safely and confidently. Ford hasn't responded. LOL!

http://news.pickuptrucks.com/2016/01/whats-the-best-light-duty-truck-for-towing-2016-texas-truck-showdown.html


Posted by: GMSRGREAT | Feb 28, 2017 11:13:21 AM

Well shoot, that is close to the ratings of GM 3500 series diesel. Let us know when GM steps up to the man

http://m.fleetowner.com/equipment/ford-2017-super-duty-payload-towing-data-released

Tom#3 I think I'd do the gm 2500 and 3500, but for 4500, ram all the way.

I disagree with the writer's assertion, "Towing a 26-foot, 9,600-pound Jayco Eagle HT fifth-wheel trailer up the twisting 8 percent grade between Paradox and Telluride, Colo., can put a strain on a pickup truck as the elevation closes in on 10,000 feet."

This is a one ton dually with 445 horsepower. Even at 10,000 feet elevation, it still has more than enough power to pull this trailer. This truck will have 312 hp at 10,000 feet.

Another great article from PUTC. I like how you presented the advanced technology and innovation engineered into this upgraded version of the segment leading engine.

Isn't it L5P, not LP5? Quite the mistake...



Post a Comment

Please remember a few rules before posting comments:

  • Try to be civil to your fellow blog readers.
  • Stay on topic. We want to hear your opinions and thoughts, but please only comment about the specified topic in the blog post.
  • Your email will not be shown.

If you have a TypeKey or TypePad account, please Sign In

Home | Buy or Sell a Truck | News | Special Reports

Powered by Cars.com. By using this site, you agree to our terms of service | © 2017 Cars.com | Privacy Statement | Contact Us