First Look: 2011 Duramax Diesel V-8 Engine

First Look: 2011 Duramax Diesel V-8 Engine

We’ve shown you spy photos and shared what our sources have told us, but now GM has pulled back more of the veil surrounding its next-generation heavy-duty Duramax diesel V-8 engine program. The illumination happened during a future product briefing at GM’s Milford Proving Grounds.

Why the need for a new round of updates to the Duramax just three years after the current engines arrived? Come Jan. 1, 2010, all new diesel-powered vehicles will have to meet tougher federal diesel emission standards that will reduce allowable nitrogen oxide levels by 90 percent from today, 96 percent from 1994 levels.

NOx is a major air pollutant that contributes to smog, asthma, and respiratory and heart diseases. It's a byproduct of diesel’s high combustion temperatures.

The new Duramax diesel engines are built to meet new clean-air regulations, plus they feature other key improvements in technology and capability. Like today’s Duramax, the Isuzu-GM joint venture engine will continue to be available in two versions.

“The new Duramax diesels are based on the same engines that have been around since 2001,” said Gary Arvan, a GM diesel powertrain engineering chief. “The 2500 and 3500 Chevrolet Silverado and GMC Sierra HD pickups receive the high-power LML motor [replacing the 2007-10 LMM], while the 2500 and 3500 heavy-duty vans receive the lower-rated LGH engine [also replacing the LMM]. Both have iron blocks, aluminum cylinder heads, and their [6.6-liter] bore and stroke are unchanged.”

LML 6.6-liter V-8 Duramax Diesel

The LML will be paired with an Allison six-speed transmission while the LGH will be mated to GM’s in-house 6L90 six-speed gearbox, which is also matched with the 6.0-liter V-8 gas engine.

The two biggest technical changes Arvan shared details about are the Duramax’s all-new selective catalytic reduction and its enhanced exhaust gas recirculation systems -- which are needed to scrub NOx down to no more than .2 grams per horsepower/hour -- as well as its approved use of B20 biodiesel. That’s 80 percent ultra-low-sulfur diesel and 20 percent biodiesel.

NOx selective catalytic reduction uses diesel exhaust fluid. The urea-based solution (32.5 percent industrial urea and 67.5 percent deionized water) is held in a 5.5-gallon storage tank and injected as a fine mist into the Duramax’s hot exhaust gases. The heat turns the urea into ammonia that -- when combined with a special catalytic converter -- breaks the NOx down into harmless nitrogen gas and water vapor.

The exhaust fluid refill point for the HD pickups is mounted under the hood of the engine, while the vans’ is positioned next to the fuel door on the side of the vehicle. The tank is mounted on the side of the driver-side frame rail.

Arvan says diesel exhaust fluid refill intervals will vary depending on duty cycle. Some customers will only have to refill during routing maintenance, such as when the oil is changed, while others will have to top off the tank sooner.

DEF fill port on Chevy Van

“If they’re towing frequently, they’ll [likely] have to fill up with DEF again sooner,” Arvan said.

To ensure that the exhaust fluid tank is refilled, Duramax-equipped trucks will warn the driver when the fluid is down to a 1,000-mile range. A series of start-up warnings -- including lights, chimes and messages -- will become more frequent until the tank is empty. If the driver continues to operate the truck with a dry tank, after a final warning and restart the truck will only operate in a “limp-home” mode that limits speed to just 5 mph until the tank is refilled.

The selective catalytic reduction and diesel-particulate filter systems depend on a diesel oxidation catalyst that’s positioned downstream, behind the engine, to start the NOx and soot-scrubbing processes. The catalyst requires high temperatures to perform. Those temperatures are achieved on-demand by the addition of a new fuel injector that’s been positioned directly behind the exhaust outlet of the Duramax’s variable-geometry turbo instead of using the engine’s eight existing in-cylinder injectors. Fuel is squirted into the hot exhaust and burns, quickly raising temperatures in the catalysts.

The LML and LGH also make greater use of exhaust gas recirculation across the Duramax’s power band than did the LMM Duramax. The system recirculates a portion of the engine's exhaust back into the engine at a lower temperature. The cooled gases have a higher heat capacity and contain less oxygen than air, lowering combustion temperatures and reducing the formation of NOx. Exhuast gas recirculation is prevalent in today’s clean-diesel engines to reduce NOx, but it’s not efficient enough in its current form to meet 2010 emissions levels in GM’s trucks, hence the use of selective catalytic reduction also.

Power ratings play a role in how much emissions equipment is needed.

“We’ve improved the performance of the Duramax in the van to 250 horsepower and 500 pounds-feet of torque from today’s 250 hp and 460 pounds feet,” Arvan said. “We aren’t prepared to talk about the new power figures for the heavy-duty trucks yet, but we won’t let the new emissions regulations bring us down [in power]. We’ll produce at least the 360 hp and 660 pounds-feet of torque [with the LML] that we make with today’s engine.”

DEF tank

We think there will be a significant power bump when the final numbers are revealed.

The LGH Duramax has a smaller exhaust gas recirculation cooler than the LML motor because of its lower power ratings. It also has a smaller radiator and cooling system.

Efficiency improvements to the recirculation system include new separate cold and hot circuits that allow exhaust gas to recirculate immediately after engine startup, when engine temperatures are still relatively cool and when the engine is idling.

In addition to burning cleaner, the LML/LGH Duramax can also burn greener. It’s certified to burn B20 biodiesel, up from the LMM’s B5 rating.

“We made a lot of enhancements to make sure the new Duramax is robust with biodiesel,” Arvan said. “The engine uses our latest-generation fuel filter that includes a coalescing filter to trap any water that could be present in the fuel. The downstream injector [behind the exhaust] for diesel particulate filter regeneration means we also won’t have a worry of oil dilution with B20 fuel from in-engine post injection [like is used on the LMM diesel]. There’s also additional heating to the fuel circuit so the filter won’t get plugged from old [B20] fuel gelling or waxing.”

Another big change to the Duramax’s fuel system is the first-time use in the Duramax of piezo electric injectors, which can react faster to fuel demands than the old solenoid injectors could. Fuel pressures are up from 1,800 bar (26,000 psi) to 2,000 bar (29,000 psi) for improved fuel atomization and combustion control. The piezo injectors run on an all-electric circuit in the engine, which helps explains the high-voltage cable we’ve seen in spy photos of the engine.

2011 Duramax-powered Chevy Van

The new Duramax keeps the same Garrett-supplied single turbo setup of the LMM Duramax, though the compressor and turbine wheel diameters and blade trims have changed. The turbo also uses the same “boreless” compressor wheel.

The Duramax also continues to use a conventional gray iron engine block, but it’s been structurally enhanced around the lower skirt to help reduce noise, vibration and harshness. Combined with a new pre-combustion fuel-injection scheme that injects two pilot injections into the cylinder before the main injection, noise levels have been reduced up to 50 percent in the 1,500-1,600 rpm peak torque operating range.

“We focused on getting NVH down in the heaviest driving points,” Arvan said.

We briefly drove a 15-passenger Chevrolet Express 2500 van with the LGH Duramax diesel under its hood. While we weren’t able to do much more than a few quick starts and stops and some city-driving route simulations, we could immediately tell the engine was much quieter than the current LMM Duramax. Arvan said the van we drove was pre-production and only about three-quarters of the way through finalizing its engine calibrations.

Another change is reduced engine-idle speed. Arvan says it’s been reduced from 720 rpm to 640 rpm in the pickups. The van is able to idle at only 600 rpm.

All new engine controllers are needed to manage the sophisticated fuel and emissions system. Arvan says they have twice the number of calibrations as the previous LMM diesel to help the engine run as efficiently as possible across the widest range of operating conditions.

The oil pump is slightly bigger, plus there have been some minor changes to the crankshaft and pistons. Aluminum heads -- a Duramax hallmark -- remain. Engine weight is said to be comparable to the LMM engine.

2011 Chevrolet Silverado 3500 mule
2011 Chevrolet Silverado 3500 mule by Chris Doane for Brenda Priddy & Co.

Arvan also says fuel economy will remain the same -- a key concern of any new diesel owner given the emphasis on clean emissions over operating efficiency.

What isn’t GM yet sharing about the 2011 Duramax? We still don’t know final power ratings for the HD pickups, and there are still a few surprises for a later date -- like perhaps an integrated exhaust brake.

“We’re working on some things in that area [exhaust brake integration],” Arvan said. “We’ll see. It’s part of future discussions.”

We’re definitely looking forward to those conversations and spending some serious time testing the new LML Duramax clean diesel.


Cool a new diesel engine! We dont need all the new emissions crap though! Its uneccesary ( the EPA's emissions standards can go **** themselves). Diesels already cleaner than gasoline without any emissons equip. and with the use of biodiesel its much cleaner!!! Diesel trucks should come from the factory with a straight pipe from the turbo-back and thats it as far as exhaust emission equip. goes. But once the aftermarket catches up with the factory computers diesel enthusiasts will just rip the emissions crap out anyway.

Cool. Would they built them for summer of 2010 ( prior to may 2010 )

Diesels are not cleaner, and anyone who doesn't like the regulations that protect us and make living in the US an great, healthy, and safe experience can go live in a country without it... have fun.

So lets place bets on length of time from when it hits dealers lots until the aftermarket boys can bypass the whole new system like they did on the current models? With twice the number of calibrations.... may take 6 months?

Fuel economy will be "the same". Is that the 8.5 mpg some guys get, or the 19 some guys get?

Can't say as I'd be too excited for a fuel injector firing into the tailpie or keeping a tank of 'exhaust juice' topped off.

id still take a cummins anyday

Has anything been mentioned about them possibly putting the new diesel into the Suburban/Yukon chassis? Or, even that other little diesel they have? I would love to be able to get a 2500 suburban/yukon with a diesel. After all, if the trucks and vans can get it, why not the suburban?

I'll keep my 2005 LLY. Figure I should be able to get at least another 400,000 out of it!

The pollution tank urea will be a reason for me not to buy this vehicle. I don't want to have to put an additional liquid in my truck. And where do you buy this urea. And if I let it run out I'm down to 5mph till I find some urea. This is not the way to go. I'm sure this system will be easily bypassed by the aftermarket but I'm still not interested in the urea solution. I'm also sure that many other feel the same.

2011 Chevrolet Silverado 3500 mule.....that is one ugly looking truck in the last photo.

Not intentionally trying to be humorous here, but if your Urea tank runs dry, can you pee into the tank to get you home since that's the primary "stinky" ingredient in urine? 5 mph going home will get you killed. Thanks, Marc

@C4DB: Nope, you can't pee in the tank to refill it. DEF has a specific formula that will be monitored by the truck's diagnostic system. Don't try to make it at home either. If I recall correctly, DEF will cost about $1.50 a gallon.

- Mike

You diesel drivers better get used to the urea idea. It's here to stay. My guess is Cummins will have it soon, too. And there's talk about making retrofit systems for older diesels as well.

dont worry theyll figure out how to bypass that crap in no time and then you can let the smoke roll ;-)

The next Cummins powered Rams will have the DEF tanks too. I've seen the mules running around town for the past few months with their big blue DEF caps proudly on display.

this is getting ridicules. my diesel days are done.

This is GREAT technology! much better than what they offer now. With the exhaust fluid refill tanks available...I may be in the market for a diesel. Of will be the FORD Scorpion.

maan, pee in the tank !?? one day I can just gas up from my own backyard with fuel converted from my septic tank.

I have to say this is a move in the right direction. First off, they got rid of the "Rich" running mode by putting an injector downstream. This means less fuel in our oil. This also means it'll be easier to run bio diesel in these newer trucks. This also means less fuel washing down the walls in the engine. I don't mind DEF. we have lots of cows that make lots of wee, I know that agricultural bi-product is one of the main ingredients in DEF. I heard that many trucker places are retrofitting to include Urea pumps with the diesel pumps as well. Soon, it'll be like going over to Schuck's or Autozone and buying a gallon of DEF. And mind you, this little 5 gallon tank lasts at least 10,000 miles. You also get a 1000 mile warning... I'm sure you can get DEF before you run out with that much warning. I mean c'mon, you'd go get oil right away if your oil lamp lit up, DEF isn't that big of an issue.

I agree with manuskrapus.

I can't understand why so many diesel enthusiasts are so proud of the black smoke and the oxides, which have kept diesel engine technologies from taking over North America. I much rather like the idea of diesels that are super clean while maintaining efficiencies over gassers, especially while towing.

And, with this new Duramax, we get the opportunity to use biodiesel. In fact, B20 is just the manufacturer being conservative. With the issue of post-injection in the chamber out of the way, any blend of good-quality biodiesel will work wonderfully in this new engine. The fact that GM is allowing up to B20 is a testament that any blend will be fine, since this will be the first on-road engine designed that will be recommended up to B20 for all drivers by any manufacturer. My 2006 Jetta TDI, for instance, is recommended up to only B5, but I can run it on B99 in the summer (can't do that with the '09, however). The only precautions I take are to half the times for the oil changes and I carry around an extra fuel filter, which I have never had to use. This new Duramax, however, with specific designs to help account for the use of biodiesel (like the specially-designed fuel filter), not even the extra precautions I take will be necessary.

Garret asked about the new little engine. I guess everything is relative, but I hardly think that of all the engines on the consumer vehicle market that a 4.5-liter V8 is little.

Anyway, GM has shelved this smaller Duramax and does not plan to introduce it unless forced to by competition. The 4.5-liter was designed for 1/2-ton and below designs and can fit in any application that currently houses the 5.3-liter, V-8 gas guzzler. If we see the 4.5, it will be most likely in the Silverado 1500, Sierra 1500, Sahara 1500, Savanah 1500, and possibly the Tahoe/Yukon 1500. If we see a diesel in the Suburban/Yukon XL 2500/3500 series SUVs, it will be the new 6.0-liter Duramax, which is designed for 3/4 and 1-ton applications.

I will not be buying one. I am a fan of the DMAX. All this emissions garbage is just going to cost the buyer ALOT more in maintenance costs, lowers fuel economy, and is just more red tape while waiting in the warranty line at the dealer.

I'll keep my 600+hp Duramax the way it is. And Im not a fan of black smoke(on the street). Good tuning is key to minimizing the smoke.

A Government designed diesel. No thank you.

Kurt, I'd never let you drive one of my trucks. If the oil light comes on, I'd recommend you not DRIVE to go get oil. I'd recommend you SHUT IT OFF.

I get the feeling a lot of people that post here don't use diesels like I do. On a weekly basis I use diesels that are 5, 10, 20, 30, and 40 years old. I like that they are reliable and are very simple. Adding all of this complexity, while it does have benefits to emissions, detracts from one of the diesel engine's greatest strengths: simplicity.

You are Truly right LT.. That the Gov. just want more money... A big waste.

@eric: I've never let an engine oil light turn on in any of my vehicles, but I was just trying to paint the picture that it isn't too big of a deal compared with the current setup. I think this new setup simplifies the engine again, getting rid of engineering issues of modern diesels. I do agree with all the added complexity, I'm a fleet analyst for a major transit agency. All I have to say is I love the simplicity of the L10 cummins, and am not enjoying the new ISL's with common rail.... These engines don't get as good of mileage, and just have soo many damn sensors telling us something is wrong at any given time... it's too bad that it's getting harder to service an L10 or M11 due to part availability :(

The next 2011 Cummins DOES NOT need DEF fluid, the EGR system is enough.

Only the chassis cab Ram for commercial use has it, which is what you would have saw driving around.

I would buy the new Ram based on that alone, along with the great new interior/exterior redesign.

Kurt, I'm glad to hear you dont' let your oil light run on your way to the parts store! I'm not sure I understand how this new setup simplifies the engine. Add a fuel injector in my exhaust system, I'm sure a pressure senssor for the fuel line there, a new tank for urea, a urea tank level sensor, a urea pump, a urea injector, exhaust filters, etc. you have a lot of added complexity. What simplifications to the rest of the system are allowed by adding these things?

Please put this engine to the FUTURE Escalades(all models), Suburbans, Tahoes and Yukon (also the XL ones) for the cleaner fuel!

Does anyone know the details on the auxiliary heater which is a part of the cold weather package if you order the rear heater in the van? It sounds like a diesel fuel fired heater used to keep the coolant hot while the motor is off but nobody seems to know for sure.

It is nice to see GM is going to meet the new stringent emissions standards and still maintain the performance of the current diesel Duramax engines.

Propane conversion with a LPG fuel injection system, leaving the gasoline system in place it the best of all worlds. Any car or truck can be converted, the huge state and federal tax breaks are very significant. In the USA, the Fed tax deduction is at least $2,500 and many states gives sales tax rebates from $500 up to the total sales tax of the whole vehicle.
Propane has 18 percent hydrogen so it burns very fast and very hot. LPG burns 4 times faster than diesel and twice as fast as gasoline. The octane rating is 105 ( R + M ) so the engine computer will advance the timing to the max for very quick acceleration and better fuel mileage with the LPG port fuel injectors.
Let's not forget the extra cost of a diesel of about $9,000, the sales tax on the 9 grand and the finance charges on the total amount and you end up paying about $12,000 over 4 or 5 years extra over a gasoline engine which can be converted after you buy it. Or save even more and buy a 2 or 3 year old truck and have it converted to use both LPG and leave the gasoline system in place.
With the port LPG fuel injectors, you will only loose about 10 percent in power compared to the same engine running gasoline. Just add dual exhaust if you really want to get more HP and let her rip.
If you drive a lot, get a national LPG fuel discount card and save about 25 t0 40 cents per gallon over the pump price.
Read my articles about propane use at "Canada free press dot com" Just plug in my name MARK SMYTH and the articles will pop up. By the way, OPEC does not control the wholesale prices of propane. Most of it is supplied from Canada or South America, so it's TALIBAN FREE....LOL.

Matk Smyth is an idiot. Propane does NOT contain 18% Hydrogen. It doesn't contain ANY molecular hydrogen...

If that's an example of the veracity of the articles you write at that rag, the Canadafreepress (which incidentally, is NOT Canadian, but is an American Conservative propaganda vehicle), then enough said.

Don;t go away mad, just go away.

Diesel Is Cleaner than Gas!!! and i give it three months till urea and dpf (Diesel Particulate Filter) delete kits are made. I Have an 06 lbz but if this lml has twin cp3's stock im trading it in when the aftermarket makes Performance parts for it!!

Simply put these engines are far too complicated far too many systems. They are killing the diesel motors by adding all this crap on top of it. All they are basically doing making people hold on to their previous generation and killing sales for new diesels because any of these guys who work on their own trucks know more junk just means more junk to go wrong.
It also means your wasting more money making this thing reliable by removing this emissions crap and then putting it back on depending on your states testing.
i will be keeping either my 7.3 in the f250 or swapping a cummins if i really need more than 800lbs of torque, and yes i like my loud ass diesel.

what about all the people who cut off the catalytic converters and run straight pipes????

Propain conversion.... Yea I really want to have to stop at the gas station AND a propain filling starion to top off the truck.

Yes I spelled it proPAIN on purpose.

Yes, fred, PROPANE DOES CONTAIN 18 PERCENT HYDROGEN. I became a member of the SAE in 1988. Since you did not even do a search on what is contained in propane, what is the real meaning to your life? Do you hate all things conservative so much that you will attack anything they say? I would suggest that when you have driven over 1 1/2 million kilometers on propane on COMMERCIAL VEHICLES as i have over the past 26 years then you would have a clue. No one you can name has written more articles with my experience of use.

I usually don't get involved in pissing contests, but...

I'm barely old enough to remember the switch from "regular" gas to unleaded, but I assume the same pointless conversations took place then.

When we find out something is bad for our children (lead) or for our planet (some diesel emmissions), we try to fix it. sometimes that requires goverment regulations to really make it happen, so get of the EPA's back.

Most of the time the solution is initially expensive and less than ideal in terms of power, etc. Deal with it.

The pendulum will swing back, it always does. Manufacturers will figure out how to make engines that do what they need to do without killing us or wrecking our planet, the prices will come down, and consumers will get used to a few extra inconveniences in order to make that happen.

We are in a couple hundred year long transitionary phase, technology needs responsiblity.

As for me, I'm picking up my new 09 Duramax next week (my third GM diesel in 8 years), and I'm hoping in the next five or six years, they figure out how to give me just as much power with minor additional cost. I'm confident they will.


I'd just like to say that I'd rather run diesel than gasoline any day and even more so than propane. Give the diesel engineers another decade and diesel engines will be almost exhaustless. Diesels are more heavy duty, last longer, more torque, tow about ten times as good, and are A LOT funner to drive. I don't care who you are you have to love the sound and feeling of a diesel motor. Enough said

All this emissions crap is killing diesel engines. Diesels would be much more efficient, run cooler, and have more power without them. The emissions control systems aren't needed. It's well known among scientists that carbon dioxide levels RISE roughly 600 years AFTER the average earth's temperature rises, not the other way around. Meaning, we're not the cause of the earth slightly warming, it's the earth's natural cycle. The earth will cool down in the future, so let our diesels be emissions free.

I sure hope their aluminum heads are better these day. They are known to have head issues, and they really have no interest in standing behind their products. When engine heads fail in less than 200,000 K with their gas engines, they better pull their heads out of their money holes when we spend 50 + K for our diesel trucks.

I wonder if DEf will freeze in the colder climate ?

OK guys we all have our own opinions on who has the best diesel and frankly i could care less! as a gentleman stated earlier if your happy with what ya have than YAY GO YOU! But i foresee lots and lots of problems in the future with all the extra technology the big three are adding to their diesel engines. The more things you have on somthing is more that could go wrong! but none the less nothing any of us has to say will make a difference in what the big three actually do! but LOL as my grandpa once said back in the day "Ford" was a family of fine cars! and "GM" was "general" motors! and without Cummins there would actually be no Dodge pickups!

Urea will freeze, bmw uses a heater on the "supply tank" on the new clean diesels. The reservoir that holds the bulk of the urea is not heated. We have had the diesels here in the states for 6 months or so and have had relatively few problems, (BMW) most problems have been attributed to programming. I'm not a "green" person, but anytime you can make a suv get 26 mpg and have almost no pollution is great.

Stupid emissions bullshit, i give it 6 months before my fellow diesel enthusiasts make that new "clean" diesel poor black smoke. Diesel already burns cleaner then gas engines. Ill stick to my LB7 duramax and ill keep pooring out the black clouds off death!

well first off to the retard before who said the "test mule is ugly" your not out to much because dumbass thats the current body style for the chevy pickups.

as for all you thinking that the new system is the best thing in the world YOUR ALL STUPID AS HELL you have obviously NEVER owned a diesel before and just need to shut up and go back to your lil ricer and support japan because your just stupid

Diesel manufators of aftermarket will have new bypass systems out about 3-4 months AFTER the public release to help us REAL diesel lovers and keep the 2011 up with piror year Dmax's.

i could honestly care less because it is what it is folks.

Testosterone! Amazing how many comments from people who are a good example of why some anmals eat their young. The EPA is activcely pursuing all chip manufacturers and shutting them down. If I see you smoking down the road I'll gladly give your plate to the EPA as those of you who need to blow smoke, if you have the money for your perks, you've enough money to pay the fine for altering eissions.
As for the Duramax, just another engine shoe horned into a vehicle... just like the Power Joke...
I'll keep my Cummins... I don't need to prove a point by stripping it of emissions.. I know it's good, nothing to prove and I don't need to make up for what I wasn't born with.

Yah, pull the emissions stuff off your new diesel, because it makes 400hp instead of the 140hp they had in 1985 (GM 6.5) and obviously blowing smoke means moah powah.

Yeah you can take off all that "epa crap" --- if you route the exhaust into the cab and keep it there. Otherwise I'm mailing your plate in the the state + the nasty 'ol EPA when I see you smoking.

I like fast cars but I don't like jerks. You can make 600hp without the smoke, if that's not enough build y'self a real race rig and trailer it to the pulls. Oh... it takes actual *work* to build a real pulling truck instead of f'ing up a work vehicle so you'll never do it.

I cant believe all of the greenies on here. Todays (pre Urea) diesels burn more than 90% cleaner than the engines just 10 years ago. Our air is already cleaner, enough is enough. It is time that King Obama and the EPA get off our asses.
The earth does indeed go through its own changes about every 16000 years. It has been 17000, so its time. You and I cant fix or change it.

The comments to this entry are closed.