New 8.3L GMC Engine

[M and E]

https://news.gm.com/home.detail.html/Pages/news/us/en/2026/sep/0921-mongoose-hd-diesel-engine.html

 

[Lantley]

Wow that's big news. I wish them luck with it. Hopefully it turns out great. The Duramax was due for a refresh. however I always stay clear of first generation things like that. Let them get the kinks out. I have learned there are always kinks

 

[RoadJunkie]

Can't say much for the timing; Bigger engines have traditionally meant more fuel usage.

 

[M and E]

Can't say much for the timing; Bigger engines have traditionally meant more fuel usage.

Gas for sure, diesel not as much. Larger displacement, same or even more torque produced, engine revs slower to produce the same energy. Smaller displacement, same torque as the larger displacement engine, the engine revs faster and relies on boost and EGR to make the same output....less fuel efficient. Plus, it will benefit form the new emissions standards. They'll add taller gears too, for sure. My bet, GM/GMC will be the class leader in torque and fuel efficiency.

 

[RoadJunkie]

Gas for sure, diesel not as much. Larger displacement, same or even more torque produced, engine revs slower to produce the same energy. Smaller displacement, same torque as the larger displacement engine, the engine revs faster and relies on boost and EGR to make the same output....less fuel efficient. Plus, it will benefit form the new emissions standards. They'll add taller gears too, for sure. My bet, GM/GMC will be the class leader in torque and fuel efficiency.

Regardless, I would wait a year or two before considering a purchase.

 

[M and E]

Regardless, I would wait a year or two before considering a purchase.

I'm with you on this one. A lot of these engines we get today are used in other countries before they come here. In those cases, I'm not as leery. That's not the case with this engine, as far as I can tell, and this is its first rodeo.

I'm only keeping this truck (26 GMC) for four or five years. ALl three should all have their ground-up rebuilds live, tested, and refined by then.

 

[Midnight Rider]

It sounds nice. But the old Duramax is a beast. No need to change any time soon.

 

[M and E]

It sounds nice. But the old Duramax is a beast. No need to change any time soon.

Agree completely, at least technically. But for me, I'm definitely going to buy one of the big three's next gen trucks in four or five years. Can't help myself!