--- title: "GM’s New 8.3L Diesel Borrows Something Crucial From the Canceled ‘Baby Duramax’" date: "2026-09-24" modified: "2026-09-24" authors: - name: "Caleb Jacobs" job_title: "Senior Editor" link: "https://www.thedrive.com/authors/caleb-jacobs.md" url: "https://www.thedrive.com/news/gms-new-8-3l-diesel-borrows-something-crucial-from-the-canceled-baby-duramax" categories: - "Chevrolet News" - "GM News" - "GMC News" - "News" - "News by Brand" tags: - "Chevrolet" - "GM" - "GMC" - "pickup" - "sierra hd" - "Silverado HD" --- # GM’s New 8.3L Diesel Borrows Something Crucial From the Canceled ‘Baby Duramax’ ![2027 Chevy Silverado HD towing a trailer with two UTVs loaded on top]() *\Chevrolet\* I'm exceptionally giddy that [General Motors]() is actually building the 8.3-liter Duramax. Call me a nerd if you want—you wouldn't be the first—but I never thought I'd see such a gargantuan pickup truck engine in my life. Of course, I was already quite fond of GM's diesel V8s, as I wrote [a detailed history of the almost-revolutionary LMK Duramax]() that the company canceled after the 2008 financial crisis. And because of my past research on that engine, I noticed something in the manufacturer's press release today. The new 8.3-liter "Mongoose" boasts plenty of impressive specs and stats. It makes 555 horsepower and 1,230 lb-ft of torque, towing up to 38,000 pounds in an appropriately spec'd Chevy Silverado 3500HD or GMC Sierra 3500HD. However, it wasn't until I read that it's being built with a compacted graphite iron block that I had my "aha" moment. See, the reason I call the ill-fated LMK Duramax "almost-revolutionary" is that it would have introduced some crazy tech to mass-market pickups almost 20 years ago. I'm talking about a hot-vee turbocharger, split-cap main bearings, and—ding ding ding—a compacted graphite iron block. [Diesel tuning godfather Gale Banks told me]() these were some of the 4.5-liter Duramax's most impressive features way back when, and GM is only just now building a diesel with a CGI block. (The outgoing 6.6-liter Duramax engine uses a cast gray iron block.) https://www.youtube.com/watch?v=dBsgw4Qm1x4 Lest you believe I'm making a mountain out of a molehill, I know that other vehicles on sale today use compacted graphite iron. Heck, the 6.7-liter Cummins in a Ram HD does, too, so it's not even new in this segment. But it's the fact that GM thought to utilize this lightweight, high-tensile-strength material in a truck engine all those years ago that has me thinking. Compacted graphite iron is different from cast gray iron on a microstructural level. Its structure is rounded and worm-like, whereas cast gray iron is sharp and flake-like. These rounded edges are better for stress management, and they increase rigidity to better withstand high cylinder pressures. Compacted graphite iron also has a far greater fatigue limit, all while weighing less. You'll save all the poundage you can when you're stuffing 8.3 liters under the hood. ![8.3L Duramax engine]() ![8.3L Duramax engine]() ![8.3L Duramax engine]() ![8.3L Duramax engine]() ![8.3L Duramax engine]() I won't pretend to be some expert in metallurgy, and I'm far from an engineer. It just clicked with me when I read that the 8.3-liter would rock CGI, as I vividly remember Gale Banks making a big deal of it in our conversation a while back. GM isn't revolutionizing the heavy-duty pickup industry with its choice of materials, but it just might start a trend of truck manufacturers bringing bigger engines to market. I guess we'll just have to wait and see on that. *Got a tip or question for the author? Contact them directly: caleb@thedrive.com* ## Author Caleb Jacobs is The Drive’s senior editor. When he’s not searching for stories or poring over copy, he’s usually driving his dump truck or wishing it was running so he could drive it. He was born and raised in the Missouri Ozarks, and he lives there today with his family. ### Author social links [LinkedIn]() [Instagram]() [Twitter]()