Could GM be loading up with a massive 8.3 L Duramax engine in their HD trucks? Well, as a diesel mechanic I’ll tell you what I, think! Well, if I remember correctly, it has been a little bit since we’ve had the old Duramax on the channel um. Actually in 2024 they bumped up the numbers for the 6.6L.

but we’re not talking about the 6.6 L today welcome back to the channel guys. Last week, the wonderful fellows from tfl truck broke the story about a potential 8.3 L Duramax engine in the works from GM. Now again, this is complete.

Rumors GM has not confirmed anything. However, I found this very interesting for a number of reasons. The first thing that comes to mind is how much power and torque this massive engine could be potentially putting out as well as how it’s going to affect Towing numbers, but also why um, it seems like we are fully in the era of trying to downsize engine Displacement as well as utilizing, hybrid or even fully, electric Solutions um for not only passenger vehicles, but also looking into pickup trucks as well, especially since this rumor engine would probably not come out until, like 2026 or later, potentially having even stricter emission protocols. By that time, tfl does claim that this potential engine could put out 600 horsepower, as well as more than 12200 ft-lb of torque surpassing forward in this ever increasing arms race between the big three manufacturers in terms of power numbers. One thing that I think is somewhat clear is that GM is probably going to be releasing a new Duramax engine in the future um.

The current l5p Duramax engine that sits in this truck right here has been around since 2017 and and I personally think it’s actually a pretty well-built engine, I think owners consumers um, would tend to agree with that rewinding a little bit. The 6 

6 L durmax package has been around since 2001 and it’s had to deal with the implementation of EGR in 2003 DPF filters in 2007, as well as the introduction of an scr system with diesel exhaust fluid in 2012 and looking at the big three manufacturers, the Duramax Platform is really the only engine that has not changed its displacement size in the last 20 or so years. Uh cumin went from the Glorious 5.9 L to the 6.7 l in 2007 and then Ford bounced around from the 73 to the 6.

to the 6.4 and now to its current form. The 6 

7 L Power Stroke um, so it does make sense that GM is potentially looking at tweaking the Duramax displacement size for the first time. Are they going with the full-blown 8.3 3 l of displacement?

We don’t know. Potentially, what could be happening is GM is trying a multitude of different displacements. Looking at the balance between power, fuel economy and Emissions, which is important, um and potentially maybe just the 8.3, is the biggest engine, and that’s why it was leaked. We don’t know.

One reason mentioned why GM could be making this big engine is to re-enter the medium duty truck World. It could be advantageous, but I honestly have my doubts about that. Looking at something like an F650, which is a medium duty, chassis that Ford makes um, they simply just put their D- tuned 67 power stroke in there, and it does just fine. Cumin puts their 6.7 l or their ISB commercial engines in everything from school buses and small freight liners with perfect functionality.

We start to see bigger cumin engines like this isl9 um in full-on class8, heavyduty Twin drive; trucks like dump trucks, fuel tanks, anchors um. So my point is: is that the current 6.6 L Duramax engine should have more than enough power to be put in a medium duty truck chassis? What about Towing could that extra displacement and power potentially help increase Towing numbers? Yes, absolutely it’s not going to hurt, but I would strongly argue that the max towing capacity 36,000 lb for the current 66 Duramax is held back by the truck and Chassis, not the Eng.

So here we have an ISL, a 9 L. Actually, it’s 8 

9, L of displacement. Officially, this thing is putting out a whopping 325 horsepower, as well as 825 lb feet of torque. Despite that engine not putting out as much power as the current 6.6 L Duramax.

 

 

 

This thing has a gbwr of 60,000 lb and can tow more weight behind it. The reason why this truck can haul so much weight is because of the drive and we got a really really beefy Allison Transmission up there huge Drive Line. This is some thick stuff up here and then look at these differentials. These are massive rear axles. So drive line has a huge impact on towability, so simply adding more engine power does not mean you have the ability to tow more weight.

 

 

 

My point is the current 6.6 L durmax is putting up more power than that 8.9 L cumin ISL engine, yet that 8.9 l engine can handle more than 60,000 lb with the right, gearing axles and drive line. I think this current uh 6 

6 L Duramax engine could tow well over the max 36,000 lb, simply just putting a bigger displacement.

 

 

 

Engine into this chassis is not going to necessarily increase that Max towing capacity. Gm would have to increase the truck and Chassis as well in order to boost that Max Towing ability. In my opinion, now it’s not all negative. I do think there are some real reasons as to why GM could potentially bring this big engine to life. Um.

First of all, tfl correctly pointed out that the current diesel engines in the big three manufacturers, the power stroke hummin and the 66 Duramax they are all very tightly wound they’re tune – is very aggressive and they’re. Just making a ton of power out of a relatively smaller displacement, and while that’s not really great for longevity or reliability, so potentially having a bigger displacement engine would mean you don’t have to have such an aggressive tune on it, and that could lead to better longevity. As well as reliability, so using cumin as an example again because well I actually work on them. Um this ISB commercial grade 67 cumin is putting out probably around 250 horsepower, maybe 500 550 pound feet of torque again, depending on the tune. Your high output, 67 commment is putting out 420 horsepower and 1,75 lb feet of torque.

 

 

 

The commercial grade engines are tuned to be strong, reliable and last the high output Commons, as well as the ISB commercial grade Commons, obviously share the same displacement. They share a ton of Base engine parts, yet the high output commin is putting out a ton more power than the commercial grade, and I highly doubt that leads to Greater longevity as well as reliability. So maybe GM is exploring the idea of a slightly detuned big displacement, diesel still being able to maintain those high power numbers. However, simply just relying on the displacement, instead of a more aggressive tune, potentially resulting in more longevity and more reliability. The last reason, and personally my favorite reason as to why GM could be making this engine comes down to emissions um with a bigger displacement, dtune engine.

If you will that’s going to mean you have lower cylinder temperatures as well as lower cylinder pressures, and this can result in lower nox emissions being produced, therefore, making it easier for an engine like that to be emission compliant potentially, as you may have heard, just got completely nailed trying to sidestep nox gas emissions, and maybe GM is trying to get ahead of the curve by going with a different route. Um smaller displacement, highly tuned diesel engines are going to have higher cylinder pressures and higher cylinder temperatures, and this is going to result in a ton more nox gas emissions being produced. As diesel engines come closer to complete combustion, they end up producing more nox gases and the way manufacturers try and combat that is by putting more EGR gas into the engine more EGR gas. It cools the cylinders which therefore produces less nox gases. Furthermore, Downstream in the emission system, you have your strr and that’s where your diesel exhaust fluid comes into play more DEA fluid, ideally, will eliminate more nox gases so, with a bigger displacement engine not having to run as hot.

 

 

 

This could mean that potentially GM could run much less EGR gas through the engine, which will greatly increase longevity as well as reliability. Well, this is your map sensor here, guys we just pulled it out, as you guys saw, it does not look healthy this. This is all carboned up from what your EGR for those of you who don’t think EGR gas is that destructive um. All this stuff is going through your engine. This is just the sensor.

 

 

 

Imagine what the piping looks like imagine what your intake looks like it’s all, going through your engine, not good, so to have the ability to put less EGR gas through your engine can be highly advantageous in terms of reliability and Longevity. If you don’t know, this is probably the number one issue with the 5lp Duramax uh. These things tend to get clogged up. This is what reads the air flow into your engine and uh. If you guys have not cleaned yours, I would highly recommend to do so.

 

 

 

This truck has about 66,000 km on it and you guys can see it does not look healthy. So that is what a map sensor should look like pretty big difference. Um, if you guys, are more interested in how to clean it made a full article on it. I’Ll I’ll link it in the description but yeah EGR gas is not healthy for an engine and if you can eliminate some of it, it should make a big difference. Now.

 

 

 

The flip side of that is, when you run cylinders at a lower temperature. The engine naturally gets more so um, so that’s something GM will have to find a way to deal with um. It could result in more clogged uh dpfs diesel particulate filters, potentially more frequent Regens, but again that’s something. Gm will have to explore, with which I’m sure they are doing if they are potentially going to be releasing such a big displacement engine. Now, some of you guys may be saying hold on Alex this bigger displacement engine is surely going to produce a bigger carbon footprint than the 66 Duramax, and you would be correct to think so.

 

 

 

This bigger displacement engine will probably, without a doubt, um create more carbon dioxide. However, the EPA at this point really is not too interested in carbon dioxide coming out of diesel engines. They are interested in three things: diesel particulate matter or soot, or that black stuff you see coming out of older diesel engines, um nox gases, which we talked about as well as carbon monoxide. Obviously, those three things are what the EPA actually really monitor. They don’t really monitor carbon dioxide, because technically carbon dioxide is not a toxin um.

 

 

 

So at this point, diesel engines are free to produce carbon dioxide as much as they kind of want before we get too ahead of ourselves again. This is all just rumors. Nothing has been confirmed um, but it is really interesting and those are some points as to why I think GM might be looking at this engine and some points as to why GM probably is is not um. Let me know what you guys think. Do you think this is just a little bit of a fugazi it?

 

 

 

It does not exist, or do you think there is some real possibility that GM is going to be looking at such a big displacement Duramax for each HD trucks in the future? As always guys, if you like the video, don’t forget to leave that thumbs up and if you like cool stuff like this, don’t forget to subscribe, we’d love to have you guys on board anyways enough of me we’ll see you in the next freaking video