Originally Posted By: dnewton3
Originally Posted By: Realtech214
Hey there! Just FYI the only engines that are AFM in 2014 to current are the 4.3L 5.3L and 6.2L
The 6.0 in the 2500 trucks is not AFM
I've heard that, too. I am not saying you're wrong, but I've found more than one reference that says your info is incorrect.
Looking at this, it shows the LY6 having been DoD (or AFM, or whatever we want to call it) since 2007 ... Would that not include all of GM's light duty trucks?
Read down into the Gen IV data ...
https://en.wikipedia.org/wiki/LS_based_GM_small-block_engine
LY6
The LY6 is a Generation IV small block V8 truck engine with a cast iron block. It shares the same bore and stroke as its LQ4 predecessor. Like other Gen IV engines, it features variable valve timing and displacement on demand. It generated 361 horsepower at 5,600 rpm and 385 lb-ft of torque at 4,400 rpm using "regular" gas, or ~87 octane. Redline is 6,000 rpm and compression ratio is 9.6:1. This engine uses L92 / LS3 style rectangle port cylinder heads, though without the sodium filled exhaust valves of the LS3.
Applications:
2007–present Chevrolet Silverado HD
2007–present GMC Sierra HD
2007–2013 Chevrolet Suburban 3/4 ton
2007–2013 GMC Yukon XL 3/4 ton
There are a slew of references at the bottom of the Wiki link; there are clear indications that other sources believe that the 6.0L in the HD trucks does (or at least did) have some form of AFM. They may or may not get the VVT, however ...
In the chart towards the end, it shows the 6.0L LY6 getting VVT, but not AFM; that's in direct contradiction to the quote in red above. However it also shows the 6.0L L77 as having AFM, but not VVT. Certainly at least some of the 6.0L engines got AFM, and some of them ended up in HD trucks. AFM may not be in all 2500HD 6.0L engines, but it's at least in some of them.
I'm not a GM engine expert; I don't know the genealogy that well. (I know the Dmax well, but that's about it).
However, what's readily apparent from my data is that the 4.8L engine has lower wear overall, and sources indicate it never had AFM.
Your point may or may not be true; but what is known for sure is that the 5.3L and 6.0L have higher wear, and most of them do get AFM. Essentially, the Gen IV engine was designed as an outgrowth of the Gen III, for the purpose of adding fuel management features, and Gen IV came out in 2005 or 2006 depending upon what source you want to credit.
Perhaps GM used AFM in the 6.0L HD trucks for a while, but then quit? I have no idea.
I'm not convinced you're right or wrong. Just noting that other sources contradict your info.
I can't comment about the 6.0 without some research, but I can most decidedly concur that the 2007 mid-year body changeover included the change to ALL 5.3s including AFM. Our 2009 5.3 was an unfortunate one to develop massive oil consumption due to the design infancy of the AFM lifters & PCV valve system.