The time has come, we finally get to see the LZ0 engine make it's way into the 2025 SUV's but unfortunately Cadillac felt the demand was too low and they decided to not release it as an option. The LZ0 is the engine code for the latest 3.0 Duramax Diesel. The prior code was LM2 and it held a soft place in many hearts as an incredible engine option offering amazing fuel economy and power to match !
With the LM2 being scrapped for the LZ0, the engineers had to find a way to stuff the extra emissions components int the engine bay. I am assuming this was one reason why it took a few years for this engine to become available as it's also included with a whole new front end as part of the update to the Tahoe and Suburban. The grilles are clearly much larger and an added area just below the grille that is likely to help promote greater airflow.
So why is this a big deal? Well, it's good and bad. Let's get the good out of the way first. The additional power is welcomed with horsepower going from 277 to 305 and the torque skyrocketing to 495 from 460. The LZ0 engine has upgraded steel pistons which are superior to the previous aluminum pistons as they can withstand heat better and also include a new bowl design which will help with noise, power and emissions. These new steel pistons are also riding in improved sleeves within the block which helps the engine to be more robust. Fuel and airflow improvements were made by way of a new intake camshaft, new cylinder head to help promote greater oil flow as well as greater airflow to work with the longer intake valves. This airflow enhancement works off the revised turbocharger with a larger impeller and overall greater airflow. More air means more fuel needed and this comes by way of new fuel injectors which outflow the previous injectors and has an updated spray pattern to better work with the new piston design. I encourage you to watch this video for even more in depth information from the changes that were found by DemonWorks when the engine was first released in the trucks.
Now for the bad... The emissions components were "improved" and by improved I mean they added more. To keep this simple, I will be referring to the exhaust filters as just that, they have very long names and for simple sake, that's what we are calling them. For the long names, see way down below. The first of 2 exhaust filters is moved close to the turbocharger to help get up to temperature quicker. Heat allows the engine to get to operating temperature and when it's at operating temperature the emissions tend to be less. This is important because they took the giant exhaust filter the LM2 had and the chopped it into 2 then made them a little larger and now we have 2 heat generators inside the engine bay. In doing so, they added a second def injector, not for efficiency but to spray twice as much DEF fluid. That's where the bad starts, the LZ0 engine in the trucks has doubled and tripled the amount of DEF fluid used. If you plan to tow with your SUV, you better be prepared because towing absolutely chugs the DEF fluid. The other down side is the fuel economy, while some trucks are reporting close to the same mileage as the LM2, many are reporting mileage lower. this sin't terrible as the LM2 got amazing fuel mileage and the LZ0 has to accept "great" mileage.
One more thing to point out is the new 2025 Suburban / Tahoe is now available with the diesel and the offroad Z71 package. This wasn't available before and the rumors were all about the cooling and ability to make everything fit. Looks like they made it fit and increased the cooling !
Final thoughts on this are that the new design is amazing looking, very aggressive and sporty. Having the LZ0 engine stuffed in will be welcomed by many and I think this will continue to be a hot item! Your loss, Cadillac.
The big words for the exhaust after treatment system - Close Coupled Diesel Oxide Catalyst (CCDOC) Selective Catalytic Reduction on Particulate Filter (SCRF)
*there is misinformation out there about the Bore and Stroke being changed. Bore and Stroke remain unchanged but the confusion comes from the thicker cylinder sleeves ( the block is machined more, the piston bore remains unchanged) and the misinformation on the stroke comes from the piston being shorter and therefore the rod becomes longer as the pin height is moved. The math is still the same, just the mass has been changed with the stronger pistons.
Changes:
Steel Pistons
Thicker head gasket
Cylinder head changed for greater oil flow and intake valves (longer)
New Fuel Injectors
Thicker block inserts (sleeves)
Revised turbocharger with increased impeller
Larger water pump impeller and increased flow
Revised coolant control valve, more simplistic
Exhaust filters increased to 3 total (2 in the engine bay and next to transmission)
Back pressure valve moved further back in the exhaust
exhaust resonator added to exhaust system (LM2 straight piped)
Second DEF injector added
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