General Motors could be cooking up a 8.3L Duramax diesel engine for their future trucks. Let’s jump into our list of what we know so far. 

1. There Is No “Official” Confirmation On This 8.3L Duramax From GM

But according to The Fast Lane Truck, “a source with knowledge of GM’s internal powertrain development” has notified them of a new 8.3L Duramax.

The new diesel is likely in development and we might not get real substantial updates and news about it for a couple of years. (Maybe an ETA of 2026)

2. The New Diesel Could Push Up To 600 Horsepower & Up To 1,200 lb-ft Of Torque

The 6.6-liter L5P Duramax turbo diesel in the 2024 GM trucks is rated at 470 horsepower and 975 lb-ft of torque. If true, this new 8.3L would see increases of horsepower by 27% and torque by 23%. 

3. The 8.3L Duramax Could Be More Powerful Than Ford’s Top Diesel 

Ford’s 6.7L Power Stroke puts out a respectable 500 hp and 1,200 lb-ft tq and the 6.7L H.O. Cummins in the RAM trucks can push 420 hp and 1,075 lb-ft tq. (These stats are for the high output towing configurations for 2024.)

4. The New Engine Is Now Being Called The “MegaMax”

This is the nickname for it, however GM will likely name it something else.  

5. Not Everyone Is Buying The News

Over at, they think it’s a rumor and that it’s totally “off-base”. They don’t think bragging rights and a bigger is better mentality fits into GM’s brand strategy. They have stated “GM is more focused on delivering the power and torque levels that are useful and balanced for the specific vehicle application, not so much for the purpose of bragging rights. Rather, bragging rights seem to be more Ford’s focus.”

Let us know your thoughts and drop a message over on our contact page.

Diesel Enthusiast? Check Out Our Diesel Drag Racing Videos On YouTube. 

We also post videos on our Instagram account

Read More Articles On Trucks & Diesels.