GM Ponders Reviving 4.5-liter Duramax V-8 Diesel

GM Ponders Reviving 4.5-liter Duramax V-8 Diesel

Last year, General Motors shelved plans to offer a 4.5-liter V-8 Duramax light-duty diesel engine in its half-ton pickups as the market for personal-use pickup trucks shrank, the U.S. economy nosedived and GM went into survival mode by shedding brands and restructuring.

Now, with signs that truck sales and the economy have turned a corner and GM refocused on its smaller product portfolio, some at GM wonder if the 4.5-liter Duramax could be revived to play a broader role, not just in light-duty pickups but in the automaker’s revamped heavy-duty trucks, too.

“The 4.5-liter V-8 is fully developed and ready,” said Mark Cieslak, GM’s full-size truck chief engineer. “[If we decided to offer it] we could launch it in a heartbeat.”

Also driving the decision to possibly pull the 4.5-liter Duramax off the shelf are tough new EPA fuel economy regulations for light-duty cars and trucks that are being phased in between now and 2016, and a new push to create fuel-efficiency standards for medium-duty and heavy-duty trucks – including pickups over 8,500 pounds gross vehicle weight – that would go into effect starting with the 2014 model year. Medium-duty and heavy-duty trucks aren’t required to carry EPA fuel economy ratings today.

“Fuel economy is top-of-mind in every vehicle discussion we have today inside GM,” Cieslak said. “Every powertrain discussion, we are breathing fuel economy.”

That has GM’s truck team wondering about using the 4.5-liter V-8 in GM’s HD pickups.

“The 4.5-liter V-8 is a legitimate contender for the 2500 segment, but are customers and [the economic environment] ready for it?” said Cieslak and Gary Arvan, Duramax chief engineer.

GM’s newly launched 2011 Chevrolet Silverado and GMC Sierra Heavy Duty pickups feature an updated 6.6-liter LML Duramax V-8 diesel, which GM says is rated a best-in-class power of 397 horsepower and 765 pounds-feet of torque while returning 11 percent greater highway mileage compared with the outgoing LMM model.

The 6.6-liter V-8 can tow up to 21,700 pounds and haul up to 6,635 pounds, but all that power isn’t necessary at the lighter end of the HD market, in the three-quarter-ton 2500 segment.

“[The 4.5-liter Duramax] could get a few miles per gallon more [than the 6.6 Duramax],” Arvan said. “It’s a high-performance diesel with a high level of work capability and fuel economy.”

The 4.5-liter V-8 might be a better choice for those who don’t need maximum capability from an HD pickup but still need a truck that’s tougher than a half-ton. It wouldn’t necessarily be compromise. It’s as strong as HD diesels were just a decade ago and more sophisticated.

“[The 4.5-liter Duramax] would have launched [with power ratings] about where the Duramax was in 2001 when it was introduced,” Arvan said.

Like the all-new 6.7-liter Power Stroke V-8 diesel that Ford introduced in the 2011 F-Series Super Duty lineup, the 4.5-liter Duramax was designed by GM entirely in-house with reversed intake and exhaust relative to a conventional diesel, so fresh air would enter the cylinders from the outer edges of the cylinder heads while exhaust gases would be dumped between the cylinder heads directly into a turbocharger. The design eliminated the intake and exhaust manifolds and other related components, saving weight, reducing size and lowering costs by up to an estimated $600 per engine compared with a conventional diesel. GM promised power ratings for the 4.5-liter Duramax would be more than 310 hp and 520 pounds-feet of torque with up to 25 percent better fuel economy than a comparable gasoline engine.

Even if the 4.5-liter Duramax cost less than the $8,395 6.6-liter Duramax (including Allison 6-speed automatic transmission), it would carry a higher premium over the standard 6.0-liter V-8 in GM’s HD pickups. Offering the 4.5-liter in GM’s light-duty pickup trucks too (as originally intended) might help make the business case that finally brings this engine to market.

What do you think? Would you opt for a lower rated, more fuel-efficient engine in your heavy-duty pickup?


I am confused. If I have two engines; one a 5 liter and another a 6 liter. Both rated at 400 HP and 400 pounds-feet of torque. The benefit of going with the 5 liter engine is that it gives you higher fuel economy. But what is the advantage of the bigger displacement engine?

@mmp: Please don't confuse this post with Ford's anticipated engine lineup for the F-150.

I wonder if GM is looking at other applications for this diesel to cover costs of production.? Like Ford selling their Brazilian built 4.4 to Land Rover

Please release this engine GM !

I would buy a 4.5 Duramax Suburban the second it comes out..


A bigger engine like a 6 liters instead of 5 liter will rev lower to reach max HP or torque if both are rated at 400 Hp and same torque. The engine should last longer and dissipate heat better.

For example Honda can squeeze out 240 Hp from a 2.2 liters engine. The specs 240Hp @ 8,300 rpm and 162 ft-lb @ 6500 rpm compare to GM 2.2 155 Hp @ 6100 rpm and 150 ft-lb @ 4900 rpm.

For the same displacement the torque is 8% higher for the Honda engine but horsepower is almost 50% higher. That's why there is no substitute for cubic inch. Or torque is related closely to displacement and Hp for the same displacement is related to RPM.

I think it's a great Idea, most people with three quater to don't use their trucks to fullest capabilities. If I haul my 11k camper trailer twice a year, then 4.5 Duramax would do just fine, while I could save fuel money for the rest of the year.
And half ton's and Suburbans with 4.5 Duramax is a must!

Hey Mike any more news on Ricardo's 3.2L V6? Would that be able to compete with this?

My thoughts are:

GM, what are you waiting for? Price this 2 to 3 grand less than the 6.6 and make it available in all BOF vehicles from 1/2 to 1 ton pickups and SUVs including tahoe, yukon, suburban, and Yukon xl. That would help the CAFE average for those vehicles and give people an improved towing capacity and better fuel economy.

GM, be the first to market with the small diesel. Basic marketing. The first to market helps a lot when it comes to making sales.

This engine is a must for the next generation midsize pickup!

the big diesels really come in to their own when pulling big enclosed trailers/goose-necks/campers/anything heavy with lots of wind resistance. a smaller diesel with better economy and 60-75% the capability would be the hot ticket for everything else like running delivery's using the bed all day, or a small flat bed truck, utility bed truck, off-road truck, commercial vans, yada yada yada....

the running gear required for this engine would completely eliminate the point of a midsized truck. a small 4-6 cylinder turbo diesel would be much better suited to that.

I think it would be a decent motor for the half ton or 2500 truck. The true heavy duty applications (such as the 3500)will probably stick with the heavier duty diesel.

GM needs to be first with a small diesel application for multiple vehicles. They have takin way to long to bring new vehicles and technology to the market place in the past.
"Just Do It"

yada, yada, yada, we've heard these proposals before. Prove you can do it first GM THEN blow your horn. I for one am sick of talk/speculations/promises. You screwed the pouch.
Smaller pickups, even half-tons (though to a lesser degree) are about getting the job done with less cost. Cost, DO YOU GET IT GM???!!! cost cost cost cost cost cost cost cost cost

GM: PLEASE build a small diesel for the ½-ton market. Everyone I talk to wants this option. GM said it themselves that the development and testing is complete, and your waiting to see the results of a business case analysis. By the time you guys figure it out, ford will have built a light duty diesel for their half-ton, and Cummins will pull one off the self for Ram. GM: Please stop reacting to consumer trends, and start introducing NEW products. Marketing these new power plants will be easy, and being 1st is usually not a bad thing IF it is your intention to lead the segment. Consumers have been waiting for a product with these characteristics for years. No one in Detroit is listening, but maybe they will when the foreign competition delivers before we do. Please keep in mind that the foreign automakers all have well recognized and developed diesel power plants (with some emissions teaks) could be here in no time at all. I drive a ¾-ton diesel daily, and would like something more well rounded for daily driving that offered power, efficiency, and longevity. Build it, and they will come!

For heaven's sake GM, you've done it before; do it again!Half-ton v8 diesel baby!

Ford is already in the market this summer with a 4.4-litre V8 diesel from the Chihuahua-plant, same that makes the 6.7-litre Scorpion for Super Duty. This coold be a good trigger for a debute soon in thje F-150.

That engine could have saved the Hummer brand. Oh well, too late now

GM- produce a 4.5-liter Duramax diesel Surburban with a self-leveling MagnaRide suspension option as well.

i don't need a hd,,but if they have a diesel half ton ,,,my god y get one today,,,ford have a new engine 6,2in gas,,a smart move to gm is bring this diesel.....if you need the hd get one,but you don't need one get half ton,,,one day the gas price come back take this opportune you have one of the best diesel on market whit proof,,,foot pound compare to gas,,ford 5,4 is not the best to pull,gm 5, need to go 6.0 for gm is good but ,,,y no price of the engine is bigger but this is marketing,play the game..

Promises of 25% better fuel economy than a comparable gas engine? Count me in. 5.3 are currently rated at 21 mpg x 1.25 gives over 26 mpg! Plus the epa always underrates the diesels. VW jetta has seen over 50 mpg and it's rated at 40ish. maybe this can translate to a heavy duty truck pushing 30mpg hwy?
Even if it's just the light duty getting 30, still an amazing feat.

If they release the 4.5L for both 1500 and 2500, not sure which one i would buy. If the price isn't substantial, might as well go with the 2500. But if it's released for 1500 only, no complaints here.

I hope this doesn't "kill" the 6.6L program. Offer both options. Some people *need* the extra power.

@Mike -

Any idea as to what transmission would back the 4.5 up in the HD chassis? Last I heard for the light duty applications GM said their 6-speed would be used. I wonder if they would use that in the HD as well or use the Allison? Or give us a choice?

@mic, you haven't towed with the 5.4 and 5.3 have you? The 5.4 is much better, though both are crap compared to a diesel.

If the small diesel is $5000 extra over the V8 gasser, would people still buy it?


"If the small diesel is $5000 extra over the V8 gasser, would people still buy it?"

You may get 2-5% at the most of the light duty market to buy it (especially suburbans and expedition owners that tow), but I also think there are a lot of the current HD diesel owners that might look at it as well. Guys that don't tow all the time and don't need the big numbers from today's diesels.

Stick it in the 1/2, i will be first in line to pick one up. Put it in the Tahoe and my wife will drive one also. I love my current 2500 Duramax but its unloaded 90% of the time and the ride gets old.

My guess with the 4.5 in the 2500's will sell for fleet customers but consumers like big hp/tq numbers and bragging rights so im sure the take rate on the 6.6 will be higher.

Come on GM build it and they will buy! You have already spent the money developing the 4.5 now recoup some of that cost.

“The 4.5-liter V-8 is fully developed and ready,” said Mark Cieslak, GM’s full-size truck chief engineer. “[If we decided to offer it] we could launch it in a heartbeat." -- GM, I am upset with you for holding out on us! Launch this thing. Stop teasing us! All 3 of you (GM, Ford, Dodge), we are ready! You're like a bunch of high school girls stringing us along!

Look at the positive feedback from this post. I would prefer a 1500 4.5, but I would take a 2500 4.5 too. Make it a $3k option, pair it with a solid tranny, and make it B20 capable.

Step back and look at this fully. It isn't any different than choosing a diesel over a gasser today. You'd probably pay $5,000 over a large gasser as an option to get it in a 1500 or 2500. Another $2-3,000 and you can get the grown up DMax. Aside from SUV buyers I am not really getting the point here. Your still paying more start up cost than a gasser and in most cases still spending up to $.30 a gallon more for fuel. This was a better idea back when diesel was cheaper than gas. It loses it's luster when you spend more to get the priveledge to pay more at the pump. This is like coming out with a slightly higher mpg 4 cylinder that costs $2,000 to get as an option and needs to run 93 octane. Feel good about the mpg numbers but don't th ink you are saving money.

GM has a Golden opportunity to beat everyone to the market and introduce something we've all been hoping for, for years! If they offered it in their SUV lineup, forget about it!!! I would LOVE a 4X4 Suburban with this diesel and would camp out overnight for several days just to be able to order one! All of their vehicles would benefit and the fleet sales of these vehicles with the diesel motors would probably be more than GM could handle.

I'm serious GM, build the 4.5 diesel, but don't be a Pansy about it and only offer it in the 1/2 ton truck! Mass produce this thing and offer it in everything that's not a car! This is your Golden Ticket now that Ford and Chrysler have backed out of building it! Although I'm sure Ford would jump back in to the race once they saw the success GM was having with their smaller diesel. Ford has a way of copying everything GM does successfully.

So maybe we can assume if it was up to a $3,000 option, it would be very popular. Anything higher would probably remain a low volume for now, especially approaching $5,000+

As an owner of an '02 Crew Cab 2500 Duramax/Allison with 195,000 mi, I would buy a smaller 4.5L in a heartbeat. I don't need 400 hp or 8000 lb-ft to pull my 6000 lb boat.
Heck I would be interested in a 4 cyl diesel in a 1/2 ton truck if it could turn out 225 hp and 325 lb-ft of torque.


Ford has a way of copying everything GM does successfully.


On the other hand Ford will come with their 4.4-litre in a few months. Long before GM even has proper machininglines installed. They let MAG take away all the equipment that was installed at Tonawanda and that will take e few years to go for the Duramax 4500. A long heartbeat...

Basically, if they've done all the work to bring it to market, they're throwing away all the development costs. It may not be a high volume seller, but as long as they make more money for each engine than it costs for them to build it, they will be ahead. I don't think this motor will be a large percentage of either the light duty or heavy duty or suburban market. But add them all up and it is worthwhile. Heck, it might even be a niche motor in the Camaro! Talk about a tire peeler! About 100 less HP than the 6.2, but that torque number is pretty sweet, and mileage would be insane. If it can outpower the 5.3 truck engine, with better mileage, it's worth it.... as long as it's not excessively priced. But that's the sticking point then, isn't it?

I whine and bitch about how much potential the Silverado Hybrid has. I'll shut up if this comes out, the potential of the 4.5L is awesome and the reliabilty is likely much better.

GM corp. Make an intelligent decision for a change!
Offer it in all of your large SUV's, 1/2 tons, and 3/4 tons.
I used to see company owned Ford diesel Excursion's all over the place. I barely see large gasser fleet SUV's. This makes more sense than a hybrid. I have yet to see a hybrid pickup on the streets.

Stick the 4.5L in the 2500 Suburban and I'm buying one. I've been waiting since the duramax came out for them to put a duramax in the Suburban. I've got a 1995 Suburban with the 6.5L Detroit that is just about ready for replacement.

Anyway, this 4.5L diesel should have been offered years ago. It's cheaper than the big diesel, it gets better mileage, and it is small enough that it can be used in a lot more applications than the larger duramax can. Trucks mid size and full sized, Vans 1/2 ton through 3/4 ton, SUVS like the Tahoe, Suburban, Yukon, Avalanche, ect; even possibly large cars. That can really help to bring the cost down. Not to mention, cost is also saved because it doesn't require the Allison transmission and the body modifications that the Allison requires.

What it comes down to, is that, with the economy the way it is, people who like diesels are having trouble justifying their purchase. ~$8,000 is a lot of money, especially if you need to buy multiple trucks. A less expensive diesel with better fuel economy makes the option more feasible for more people/companies. In this case, more options is a good thing. Especially if it allows GM to sell more trucks since they have something the competition doesn't.

At roughly 78% of the hp and 69% of the torque of the 6.6 Dmax, and Better fuel economy. IF GM could keep the cost lower then the 6.6 I would consider this as a 2500 even if I can't stand the look of the GM HD's. Hell I think it would get better mpg's then my ranger. It would have to be a denali though.


Especially if it allows GM to sell more trucks since they have something the competition doesn't.


Wrong, Ford is coming with a similar engine this summer. It can be monuted in a F-150 like a heartbeat. GM will lose marketshare if so.

Instead of the 6.2 in the F-150, put the diesel.

@EB - Especially if it allows GM to sell more trucks since they have something the competition doesn't.

You've attributed this comment to me. I did not say that.

Since you brought it up - if GM is the first one to put this on the market, they will gain market share.

To quote the news story:
"It’s as strong as HD diesels were just a decade ago and more sophisticated."

Decent power with good MPG and a reasonable price - that's what people need.

We need to get over the whole my @#$% is bigger than your @#$%.


Would I opt for this, hmm? How about, we are tired of this carrot dangling. See you in an EcoBoost F-150, idiots...

Oh and only put it in the HD's, great call. You all know so much more than us average minded folk.

Do gm and brett farve have the same pr people? just make a decision and go with it, and stop tormenting people. for the record I dont like either so it might be even more annoying to me.

I would buy a 1/2 with the 4.5 in a heart beat . We need a lighter duty diesel . Come on GM wake up there would be a big market for a 1/2 diesel. After owning 5 , 6.6 duramax I have gone back to a 98 Z-71 6.5 because I do not need that big of a truck GIVE US A 1/2 ton DIESEL !!!!!!!!!! PLEASE !!!

Oh if ford does put the 4.4 in a f-150 I would push my Chevy before I would buy a ford

If GM would offer this with either the max tow 1500 or a 2500 thats not crazy $$$, they would finally have something to replace all those <06 1500 heavy half crews with the gas pig 6.0Ls that fill the campgrounds everywhere...

"I'm serious GM, build the 4.5 diesel, but don't be a Pansy about it and only offer it in the 1/2 ton truck! Mass produce this thing and offer it in everything that's not a car! This is your Golden Ticket now that Ford and Chrysler have backed out of building it! Although I'm sure Ford would jump back in to the race once they saw the success GM was having with their smaller diesel. Ford has a way of copying everything GM does successfully."

Posted by: Chris | Jun 9, 2010 9:57:28 AM

Uh Yea I don't think Ford copies a damn thing from GM there buddy. More like GM knows the Ford 4.4L is coming and they are getting worried. The 4.4L is being built for Land Rover but don't think for a minute that Ford doesn't already have plans for it in their trucks. Since its already in production it can be transferred over in a very short time.


I think you are right on the spot with " The 4.4L is being built for Land Rover but don't think for a minute that Ford doesn't already have plans for it in their trucks. Since its already in production it can be transferred over in a very short time."

It´s a low volume production for Land Rover that is starting this summer and I think the F-150 is a hot candidate. When it´s in production it can easily be made in huge numbers.

Gm should be very agressive with getting the 4.5 out.

Should Ford jump all over this - A 3.5 EB and a 4.4 diesel as a "global" engine in cars, SUV's and pickups would be tantemount to a coup de grace for the competition.

@ EB, Shawn

Could you give us the link that proves your point about Ford's 4.4 coming out cause I haven't heard that yet. And are you sure its being built for America and not just Europe since it's Land Rover? As for Ford not copying GM, Fords new 6.7L PSD is a direct rip-off of GMs 4.5L, just a larger version (thought that was pretty obvious to everyone).

@Greg - there is usually a 3 - 5 year time frame for a product development cycle. Ford probably started work on the 6.7 around the same time as GM started on the 4.4.

If you left engineers alone to come up with the best design for an engine, transmission or truck - they'd all come up with a similar design.
The laws of physics are immutable.
The best design is the best design.
Trademarks, patents, copyright laws are the things that force engineers to come up with different ways for doing the same thing.

GM ponders, the competition delivers.

@Greg well some of the info is right on this site. I know the new plant in Mexico that builds the 6.7 will also have a 4.4 line that will build that motor for Land Rover. So in theory Ford is already building the 4.4 or at least set up to start at any time. Maybe Mike Levine can comment on this? Also I believe I saw the same info on LLN's site also. But this is still my favorite site. Oh and I'm not knocking GM in anyway, I think this would be a great ideal for them to do also, but I'm still a Ford guy though.

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