GM Shelves Innovative New 4.5 Liter V8 Diesel

By Chris Haak


2009 Duramax Diesel 4.5L V-8GM had been expecting to begin production of its all-new 4.5 liter Duramax light-duty truck diesel (pictured at left) at its engine plant in Tonawanda, New York this fall, but has now put those plans on hold, according to Automotive News.  The company blamed its deteriorating financial situation for the decision, and has noted in the past that all product decisions are up in the air at this point.  If GM ends up re-starting the program, it will take a year from the program’s re-initiation for the engines to reach Job 1.  One problem that GM has traditionally had over the past few years, and has become worse lately as it’s hammered on all sides by bad news, is that it repeatedly starts and stops projects, which adds significant time and expense to them.

The new engine was to have produced 310 horsepower and 520 lb-ft of torque, while returning highway fuel economy in the mid-20s.  The initial application for the new engine was to have been the Chevrolet Silverado and GMC Sierra full-size pickups.

It really is a shame to see what was seemingly destined to be one of the best engines in GM’s history shelved – and quite possibly cancelled permanently at some point.  The engine is a clean-sheet design that is able to fit into the space normally occupied by the very-compact small-block gasoline V8.  That meant that as long as the transmission application could handle its 510 lb-ft of torque (not necessarily a given), it could fit into nearly any medium to large GM car, truck, or SUV.  Possible applications that had been in the rumor mill from time to time included the Lambda crossovers (Enclave et al), Zeta cars (Pontiac G8, Chevy Camaro, Holden Commodore), and even the Cadillac CTS.  The new engine’s small footprint was attributed mostly to the intelligent way in which its exhaust and intake plumbing was reversed from the norm; instead of the exhaust exiting the engine on the outside of the “V,” it exited in the valley, and the turbocharger could be nestled between the cylinder banks for a much more compact design.

As we noted in our “Diesel Invasion” article way back in 2007, many manufacturers had plans or were at least considering selling diesel-powered cars and trucks in the US, hoping that bad memories of self-destructing Oldsmobile diesels from the 1980s were a distant memory for most consumers.  Since then, fuel prices shot up significantly, and diesel fuel prices exploded to more than $5 per gallon in most places.  Of course, the ensuing global economic collapse pulled diesel and gasoline prices down to lower levels, but seeing diesel prices last summer certainly didn’t help make the case for more diesels in the US.  Honda has shelved its US diesel plans for the Acura TSX, apparently because of emission worries, and Jeep is no longer selling the Grand Cherokee CRD that I enjoyed last summer.

There is another hope for the Duramax 4.5 liter diesel as well.  GM Powertrain spokeswoman Susan Garavaglia told Automotive News that it’s possible that rights to the engine could be sold to another company.  Auto writers who have sampled prototype vehicles powered by that engine have said that it was as smooth and quiet as a gasoline engine, and there are plenty of companies looking for new light-duty diesels for their half-ton truck applications – Toyota among them.

With the sales of GM’s expensive two-mode hybrid pickups and SUVs showing some pretty pathetic numbers, GM could have had better-performing, more-efficient vehicles in the light-duty truck class, while probably selling the 4.5 liter Duramax option for less than the nearly $10,000 premium the hybrids are going for, and for less than the $8,000 price difference the larger and more powerful 6.6 liter Duramax adds onto the price of a gasoline V8 in the three-quarter and one-ton GM pickups.  The Duramax 4.5 liter will probably turn into an interesting footnote in GM’s history, and yet another example of the coulda, shoulda, woulda that afflicts this company so consistently.

COPYRIGHT Autosavant – All Rights Reserved

Author: Chris Haak

Chris is Autosavant's Managing Editor. He has a lifelong love of everything automotive, having grown up as the son of a car dealer. A married father of two sons, Chris is also in the process of indoctrinating them into the world of cars and trucks.

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  1. is getting thrashed by the current environment. It could have been first in the market with this sort of engine in kight trucks, but they don’t have the money to bring it to market. Someone else will bring a similar engine to market soon, and then the unknowing public will say, “Man, GM is just so dumb. They should have produced an engine like this.” I’m not a GM fan, but they just can’t win these days.

  2. Quick clarification, we won’t just outright sell this diesel technology to another company. If a strategic partnership arises that provides us with enough capital to build GM vehicles with this engine, then we would consider sharing the technology with another company.

  3. I think the ultra low sulfer mandate has killed a lot of the market for small diesel engines. With diesel now consistently costing 20-25% more than gas the payback time for the more expensive desel engine is effectively infinity.

    The market is clearly light trucks. A large number of 1/2 ton Silverado buyers would opt for a small diesel if one were offered, just as a large number of Ford F-150 buyers would opt for a small diesel. The question though, is how much would that canibalize sales of 3/4 ton trucks.

    From a consumer standpoint, the best thing would be if Cummins could offer their I-6 diesel to all of the US manufacturers. Everyone I know who uses a pickup for towing wants the same thing, an F-150 (Ford), with an Allison (GM) transmission, and a Cummins (Dodge) engine.

  4. God forbid we actually get a smaller diesel engine in this country from somebody besides VW. While I would be interested in a CTS with a V8 Diesel, I’d find a compact pickup with a I4 or V6/I6 diesel engine infinitely more useful and attractive. My hopes for something like that were dashed when Daimler divested itself of Chrysler and the Jeep Gladiator concept died.

    @ Mark: Europeans have been operating under low sulfur restrictions for literally decades and diesel fuel is cheaper there than unleaded gasoline. I’ve never been able to figure out why (short of typical conspiracy theories) diesel in the US is so much more expensive than regular, even before the low sulfur mandate. That’s one of the reasons diesel passenger vehicles are so popular over there.

  5. Phil, thanks for the clarification. I, for one, would love to see this engine see the light of day.

    With Ford supposedly also working on its own smaller V8 diesel for light duty trucks, GM may be missing a good opportunity to get a jump on the competition and have some serious torque/mpg bragging rights.

  6. The Australian Zeta cars are slated to get TDi engines next year but not (and not ever) this monster….they are looking at a VM Motori engine about 2/3rds the size of the Duramax…..and not far short of the grunt either.

  7. GM needs to “shelve” a lot more than that…Sad to say, but the company really needs to fail instead of having countless taxpayers continue paying exorbitant salaries for unionized GM workers to produce products that no one wants/is buying…

  8. Mark: “I think the ultra low sulfer mandate has killed a lot of the market for small diesel engines. With diesel now consistently costing 20-25% more than gas the payback time for the more expensive desel engine is effectively infinity.”

    First, as stated by others, it is not ULSD that caused the higher cost of diesel.

    In my area of NC today, diesel is within 6% of the price of unleaded, 4% if tax differences are taken into account.

    I suspect that the major cause of the previously high cost spread between diesel and gasoline was the high demand (much HIGHER price) for diesel in Europe and Asia.

    Those previously high prices and the diesel/gasoline price spread are not sustainable now that petroleum demand has fallen approximately 20% from 104 million barrels per day (2007/8) to about 84 million barrels per day today.

    This 20% reduction in petro demand is an excellent indicator of world economic conditions.

    Further OPEC will probably cut production volumes any day now to push up crude prices.

    Further, as domestic diesel fuel demand increases relative to gasoline, the US refineries will consider shifting their processes to yield more diesel versus gasoline, as has been done in Europe. This will be necessary to keep the diesel/gasoline production ratios in alignment with demand.

    This should stabalize diesel fuel prices versus gasoline.

    So GM may be missing an opportunity trying to bring out the NEW 4.5 diesel … BUT … they are really “missing the boat” completely by not introducing their MATURE 1.3 to 3.0 liter turbo diesel engines (Opel from Europe) here in the US!

    Just an opinion ….

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