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?


Oh and although both the 4.5 and 6.7 are almost identical to say it was a knockoff... I think both companies keep their cards to their chest pretty good so I'm sure this was just a case of both companies realizing that this was a better design. It saves on weight and its more efficient. Funny though that it is almost identical to the 4.5 but GM says that the way the motor is set up it is torture... well then what would that make their 4.5 then?

@Greg, the Range Rover is using a Ford-sourced 4.4L V8 diesel for the 2011 model. It's all over the Internet.
308HP/516lb-ft in the Range Rover with 23mpg average. Not bad considering it's dang heavy and is full-time 4x4.

As far as Ford copying GM's diesel? How would Ford get the GM diesel that's not even out yet to copy? Also, did you know the GM 4.5 is just a bigger version of the 2.9L V6 that was developed as a joint venture between GM and VM Motori? The diesel technology came from VM Motori, not GM.

As far as who patented the reverse air flow, I have no idea. I think the concept came long before these GM diesels. I think GM unveiled it first, that was it.
Ford brought it to production first, none of that really matters anyway. You would think if GM invented it, they would have patented it. They patent screw holes, why wouldn't they patent something as big as reverse airflow?

"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)."

Not true at all. The GM 4.5L wasn't announced until June of 2007. In the same month, Navistar sued Ford for working on their own diesels in preparation for a split between the two companies. We were already seeing 6.7L spy shots by early 2008. There is no way Ford would have had enough time to develop a new diesel based on GMs designs unless they practiced industrial espionage.

If you want to go back a bit further, BMW actually released the basic reverse intake/exhaust design first in that time frame. Their 4.4L gas V8 for the 2008 BMW X6 features a reverse intake/exhaust flow design, just like GM's 4.5L and Ford's 6.7L diesels.

"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)."

Not true at all. The GM 4.5L wasn't announced until June of 2007. In the same month, Navistar sued Ford for working on their own diesels in preparation for a split between the two companies. We were already seeing 6.7L spy shots by early 2008. There is no way Ford would have had enough time to develop a new diesel based on GMs designs unless they practiced industrial espionage.

If you want to go back a bit further, BMW actually released the basic reverse intake/exhaust design first in that time frame. Their 4.4L gas V8 for the 2008 BMW X6 features a reverse intake/exhaust flow design, just like GM's 4.5L and Ford's 6.7L diesels.

just do it gm

I don't have anything new to add, but I want GM (and the other manufacturers) to know that a 1/2 ton diesel is the truck I have been waiting to buy. I hope they are listening.

This would make entirely too much sense.
They'll never do it.

GM is too busy shredding documents to have time to build a new diesel.

@Mike Levine, I know that this is a shot in the dark, but are there any plans of these comments being sent to GM as it would be an indicator (even if it is a small one) that there are people out there waiting for a small diesel to be placed into a half-ton truck? I agree, that despite what GM has gone thru in the past year or so, they need to stop the pondering and get this 4.5 Dmax into production.

Yes GM, put the diesel in 1/2 ton's, suburbans, and vans...NOW

Oh ya, more good news from GM. 5.0L cummins, or 4.5L Duramax, yough decision to make. 8 speed trannies and half ton diesel will come, that you can be sure of ,just be patient.

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?

1. The 400hp 5L would make less torque aka tow less payload V.S. the 400hp 6L would make more torque aka tow more payload . . .

2. The 6L would last longer in the long run . . .

Why do you think a 350hp 12-14L engine will last 900,000 miles as where a 350hp 5-7L engine will only live 200,000 miles ?


LOL so Mike... tell me, by that logic, if I bore my engine out, will it last longer? Because it will have a bigger displacement. Therefore the structural integrity of the crankshaft, connecting rods, pistons, fly wheel and everything else automatically gets tougher and lasts longer? LOL. So even though the GM 4.8 and 5.3 are the same engine, the 5.3 is much tougher? And even though the Ford 4.6 and 5.4 are the same engines, the 5.4 is obviously tougher?
What if the 5.0 had a long stroke design, and the 6.0 had a very short stroke but a larger bore? Would the 6.0 still have more low-end torque? What if the 6.0 was naturally aspirated, had 400 lb-ft, but the 5.0 was an EcoBoost or supercharged and had 700 lb-ft?
What if the 5.0 was made of thick titanium in every part and the 6.0 was made of thin 24ct Gold?
Sorry Mike, I should let you live in the world of simplicity in peace.

C´mon bring the 4.5 Diesel for the Tahoe and you´ve got a cashcow here in Europe. It might even work with a half ton pickup.


Don't forget, though, that horsepower is nothing but work done over time, and that, all things being equal, the engine turning a higher rpm is going to develop more horsepower. It'd be interesting to see what the Honda's numbers are at 6100 & 4900.

Anyway, GM, why stop at a 4.5l V8 for fullsizes? How about a 2.0-2.5l I4 or I5 for midsizes and smaller, both cars and trucks? 

It's long over due. U.S. drivers like trucks and SUVs and there are no full size SUVs with a diesel. With this 4.5L diesel, it would be well suited and widely accepted in the SUV market. Additionally, diesels perform much better and provide tremendous low end torque, provide better fuel economy, and are as clean, if not cleaner than gasoline engines. It's about time!

Build it and they will come!!! I agree with one of the other it and offer it in everything that is not a truck or even in the bigger sedans! Anybody been in Europe lately or any other part of the world. Ford, Cummins, and GM all have the half ton diesel ready to go. Pull the trigger!! I would be the first to order a 4X4 Suburban LTZ with a 4.5 Diesel in it!! Better yet, put it in your full size vans with the 6 speed and AWD and I will have it converted at Explorer and have a Perfect people mover, 4x4, compfortable, roomy towing machine that gets relatively good fuel economy and is fun to drive because it is not an underpowered dog. I drive diesel VWs now and there is nothing like driving a diesel. The torque is just plain exhilerating! and you don't spend all your time at the gas pump either.

Put it in the Tahoe/Yukon/Suburban and I'd be trading in tomorrow.

Diesel in a 1/2 ton pick up...good idea! A better idea? Build a 1/2 ton crew cab with a 6.5 foot box!!

It will take some two years to production after/if GM pulls the trigger. The entire machining equipment installed by MAG at the Tonawanda plant was taken away at the time GM froze the engine. GM people are saying that it will be made "in a heartbeat" but the heart was stopped.

Anyone see where the new Ford 4.4L gets 30mpg + in the new Land Rover? If it can pull those kinda numbers in that heavy hog then what could it do for the F150 and F250? As someone who only pulls a camper or a trailer a few times a year I don't need all that extra horsepower... I will opt for fuel mileage.

Land Rover--
it’s the company’s new 4.4-litre twin-turbo diesel, which replaces the current 3.6 V8. We hear power goes up from 267bhp to around 310bhp, the torque output climbs from 472lb ft to 516lb ft (a nice round 700Nm), and fuel consumption improves from 25.4mpg to over 30mpg. The CO2 figure gets better too, dropping from 299g/km CO2 to somewhere in the region of 250g/km. Made at the same plant that makers the 6.7-litre Ford V8.

Dodge and Cummins had an I5 back in 06 planned for the 09 Dodge 1500 and shelved it. I know because I was one of the engineers. I recently bought an old GMC 2500 to pull boat cause no one has offered a 1500 diesel. I had enough saved for 50% down, but no one makes what I want so buy old and deal with repairs. Whoever has the small diesel first is the future of 1/2 ton trucks. Make it no more than a $3000 option and for god sakes give the option of manual or automatic tranny.

2010 Suburban 2500 Z71 Duramax 4.5 Liter
This is a prototype that was recently seen and photographed at the Louisville RV show.


I have a 96 GMC 2500 Xcab long bed 2WD 6.5 diesel now with 185000 miles. No problems since injector pump was rebuilt under warranty. Mixed driving with about 30% pulling a farm trailer with hay or farm equipment. I have record of every gallon of fuel used and for the first 100000 miles I averaged 15.26 mpg. A gasser to give the same performance would have done well to average 10 - 11 mpg. So much for making the case for diesel. The 4.5 has better specks (HP and torque) than my 6.5 and with MUCH better economy. Come on GM, do it and I'll trade at the drop of a hat. Otherwise I'll keep my 6.5 for another 100000,

Remember when the old cars had less than 200 hp? I want a chevy 1/2 ton with 150 hp diesel and 35 mpg. I am retired, speed kills and 150 hp diesel would go any posted speed limit in the US of A !!!!!!!! Just not 80 in the quarter mile......slow down a little and save a lot...

Get er done........

I want to know where is this engine going to be made? It better be made at the Dmax plant where it all started.

I'l tell you what, this sound's like a winner and if you guy's don't get around to offering the American public an efficient,reliable,midranged powered , do it all vehicle soon , the Japanese or Chinese are going to, hell they're already building these types of truck's in other part's of the world and have been for years, the only reason were not driving them is because the big 3 wont let them import them, because they now once we get our hands on them, it'l be no going back to 2nd best, so boy's if you got winner bring it on !!! or we'l just sit around and watch what used to be the backbone of this nation go out of business , because the American people can't afford second best anymore ! Don't get me wrong I drive a big Dodge diesel and love it , but if I could buy a 20+ mile / gallon 2nd family vehicle (utility)truck my wife would be driving one too !! the technology is their and has been for year's , but the big 3 and the oil industry are in bed together and love having a choke hold on the american dream, instead they would rather suck us DRY !!! Power to the People , so to the big 3 I say if you want my $, it better be a superior more efficient product or I can wait and fix what I own for the next Decade !!!

finally. With a family including a 6'2" son who camps, hauls mulch, firewood and other 1/2 ton level home owner stuff, I want/need a nice riding daily drive 1/2 ton that can gets 25+ mpg every day back and forth to work while handling all the fun stuff upto my 5000 lb trailer we use half dozen times a year. I agree, my diesel jetta gets almost 50mpg which is well above the advertised rating. 1/2 ton silverado 4 door is the perfect fun family truck, with 25+ mpg, thats huge.....

Sell this as a retro-fit crate engine to convert from gas to diesel. I would be able to drive my half-ton to work everyday with this motor.

GM please make a half ton diesel, I would buy one the second they go on sale!

Mr. Mark Cieslak What are you waiting for? Be the first of the big three to launch this 4.5 Duramax diesel in the half ton world. With the possibilities for the 3/4 ton,suburban,suv's etc. what a seller! Now I'm going to wait before purchasing to see what you decide. I'm a definite buyer. Thanks Eric

I am looking for a mid-sized diesel truck for hauling a trailer - the 4.5 with six speed automatic and exhaust braking would be perfect.

I am an avid Avalanche buyer but am concidering the HD because of the Diesel but it would be had to part with the Avalanche's ride and versitality. When i worked at GM I heard that this engine was in Development and woud beutilized in all variations of the Light duty line. I am hoping this still holds true because as others have said I would be the first to put my name on the list, reguardless of price.

I would trade my 2500 6.6 dmax for a 1500 4.5 dmax. It would be a smoother ride, better fuel economy, with plenty of power. I can only hope for one soon

Hopefully GM pulls the trigger on it. They may be waiting for the apparently less than rosey initial public offering. In the meantime Ford's EB will take away more market share.

A suburban with this engine would be it GM!

Personally, I thinks its an awesome idea, as for the initial cost, I buy my diesels to keep not trade all the time. So, there for the initial cost is recouped in the longevity of the engine. I've got a '04 Duramax now that I will never get rid of, until it falls apart, it gets around 16-17 city and at 70 or under on the intestate with cruise set it gets 22-23, at 75-80 it will still get 18.5-19. I'd be interested to see fuel economy under a load for the 4.5, (the fuel mileages above are just truck, no load). I've got a 35 foot fifth wheel travel trailer it will drag it fast as you want to drag it, cruising at 75 with the fifth wheel, I'm getting 17. So GM all I can say is "SHOW ME"!! AND NO, IT IS NOT CHIPPED OR NO PROGRAMMERS!!

If this comes out I'm running to the dealership to get a 4.5 crate with matching tranny for my Astro since the 4.5 was also designed to be a direct drop in replacement for all Chevy small blocks. With the Allison tranny and proper differential gearing I could get over 25mpg with it.

I believe the 4.5 diesel would be a boon for GM however top brass is so slow and confused that they will just screw it up and drop the ball once again. This engine can represent all the right moves in one fell swoop , American jobs, quality engineering, energy efficiency, environmental consciousness with the use of biodiesel fuel and the potential for even more MPG with hybrid technology already utilized with GM v8 engines.This engine can go into luxury sedans, trucks, vans, military vehicles and maybe even find its way into marine applications. HELLO??? Does anyone have a pulse at the heartbeat of America????

In 2000, I was looking for a vehicle to pull 10,000 lb. wnclosed car haulers in the winter time, and haul 3-4 riders, saddles and horse trailers in the summer. Chev/GM had no diesel option in the Suburban. I was preparing to trade in my 6th Suburban since 1976. Several GM dealers and GM itself, said a diesel Suburban was a year or two away.


I have 325,000 miles on a 2000 7.3L PowerStroke Excursion Limited 4x4 (9200GVWR) with the 4 speed automatic. It was chipped almost immediately to 300hp and 625lbft. This has been excellent for my needs.

The horsepower of the GM 4.5L V8 diesel is slightly more than what I have now, the 100lbft less of torque, would be well compensated by the move up to a 6 speed transmission. In a 2500 Suburban 4x4, the empty weight with a full load of fuel, would probably be 1,500-2,000 pounds less than my 8,000 pound Excursion (44 gal. of diesel). It would have less interior room, mostly less leg room in the second row, better ride with IFS front suspension, and nice ergonomics.

When not towing, I get 18mpg, With a 10,000 pound 8.5' wide 6.5' tall interior trailer, I get 11-14mpg now. I think a 4.5L Duramax 2500 Suburban would do as well, if not better. Some type of an automatic leveling suspension system, would be terrific, but If I have to put on airbags, I will. Mr. Ford III abandoned the Excursion due to pressure from his environmentalist buddies, it is time for GM to step up to this market, and this would be a great package.

Many recreational and business owners, who tow 10,000 pound and less trailers would love this solution to their needs.

I know I would.

I see this is an old blog, but one more comment can't hurt. I hope GM has seen all of these comments, because the bottom line is that diesel engines are simply better than gas engines. I bought an 03 duramax and it was great other than the fact that it was more truck than I needed. I only bought it because I prefer diesel engines. At the end of the day, gas engines don't belong in ANY size truck. I'd buy a diesel Tacoma if they had one here, but would greatly prefer a half-ton truck.

I've got a '95 Yukon. The very best vehicle I've ever owned. Still love driving it. Especially on long trips. Only issue I have is 1990's fuel consumption rate at 2010's fuel prices. I've been looking at the German diesel SUVs. If GM doesn't offer one, I may just have to get one of them. I'd rather buy American. A 4.5L diesel Yukon will be perfect, I'd trade in my '95 in a heartbeat. or better yet, I'll keep the old lady and get her a diesel stable mate.

I've always been one to buy a genntly used SUV keep overall costs down for my family of 8. No I'm not purchasing a freaking minivan that would get us all killed if we were in an accident. I love the suburbans, everyone has enough leg room and comfort to help keep the bickering down. I've been pissed for years that I can't get one that achieves 25mpg city and 30mpg highway yet. Now I learn GM, you have a power plant that could most likely do this in a suburban, escalade, Yukon xl. Knowing you never find a gently used diesel and if it would get that economy for the same price as the gas version or a couple thousand more I would actually pay the astronomical $45k - $50k price Tag for a new one. Why even waste the money producing the standard gas option anymore? The suburban is awesome, I tos the family around all month, drive it to and from work. Then use it onc to twice a month on weekends to tow bass. Boat to tournaments. This with the third row seat out, second row flipped down and an air mattress in the back for me to camp in wet washington. Do it and i'll trade in my 2004 2500 suburban 3 row bench seats right away.

I'm with you Michael. Suburbans are the end all be all vehicle. I have a 2500 Suburban that has had myself, wife, 2 kids, 2 dogs, luggage for all, toys, pack and plays, and a trailer with a 60 hp Kubota Tractor with a front-end loader all at once. Yes the Vortec got me everywhere, but thank God it has a 37 gallon fuel tank. Yes these are huge vehicles and I really don't give a dang abut the dirty looks I get from the metrosexuals in their Cooper minis getting 50 MPG or whatever. It's the tools we need, and a diesel engine would be the ticket. My next truck, which will probably be this summer, will be the new Silverado HD. It actually has a pretty good price for what it is. Put a camper on it and it is pretty much a Suburban, just with some guts. Also, wouldn't have to worry about wife compaining about my muddy waders in the back. :)

I would love to see GM come out with the 4.5 in the HD Trucks! The 6.6 Duramax is great but in all honesty it makes WAY more power than the average buyer will ever use. I have one of the heavest skidsteers Case has ever built and the power rating out of the old 01 Duramax pulled it with ease, so I don't see why the new 4.5 couldn't do the same, but while still using less fuel. Also the 4.5 would be a great option for those who are looking for something inbetween the 6.0 (gas) and the 6.6 Duramax

I'd buy one in a HEARTBEAT. GM get off your ass and do something that actually makes sense for once. Not like that Chevy Volt that will go no where. I mean look at the Mustang. How much money did you lose dragging your feet in producing the Camaro. It's a no brainer. More MPG, more torque in a 1/2 ton pickup. First on the market. Ahh, let me see a gas engine that gets 15 MPG or a Diesel that gets 30 MPG. HMMMM. DUH>>>>

General Motors desperately needs this motor.

Ram desperately needs the 5.0L Cummins.

Ford can not have all of the glory?

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