Will General Motors design and build their own straight-six heavy duty diesel engine? It can be a 6.0-liter displacement or bigger and easily hit 1,000 lb-ft of torque. This is based on a question we recently received from Adam S, a TFLtruck viewer.
Adam writes:
“With the 3.0L straight six Duramax being so well received in the full size half-ton market, do you think there is any possibility GM will release a straight six configuration in the heavy duty class? Also, Ram + Cummins + Allison would be a major $$$ win for FCA.“
There is no information that suggests that GM is currently working on a whole new turbo-diesel Duramax engine for their heavy duty trucks. There is not insider source with this information at this time.
Still, Adam brings up a very interesting topic. What’s next for the big 6.6-liter Duramax V8 that is currently being used in the 2020 Chevy Silverado HD and Sierra HD trucks? Will GM give the well-respected V8 another update soon or is it time for something completely new?
GM has recently been on a roll with new truck engine introductions. They recently introduced a 2.7-liter I4 gas turbocharged engine in their Silverado 1500 and Sierra 1500 trucks. This is a very high-tech engine with a new turbocharger inlet design, different cam profiles (including cylinder deactivation), and a new coolant management system. The current output on this engine is 310 hp @ 5,600 rpm and 348 lb-ft of torque @ 1,500 rpm.
There is also the aforementioned 3.0-liter I6 turbo-diesel Duramax engine that earned our 2020 Gold Hitch best towing half-ton diesel award. The new diesel has even power delivery and a great 33 MPG highway rating by the EPA. The power output stand at a class-leading 277 hp @ 3,750 rpm, while the torque is also a good (but not class-leading) 460 lb-ft @ 1,500 rpm.
What if GM developed a heavy duty version of the straight-six diesel engine? What displacement would it have and how much power would it deliver? Let us know in the comments section below.
- Yes, GM should build and sell an all-new HD I6 Duramax.
- No, they should further refine the 6.6L V8 Duramax.
In my personal opinion, a new straight-six makes a lot of sense. If GM can maintain that smooth power delivery we see in the 3.0-liter I6 and provide good economy and emissions performance – yes! It should be possible to get the horsepower close to 500 hp and the torque to over 1,000 lb-ft.
