Tearing down the engine I discussed in this thread
https://www.ford-trucks.com/forums/5...new-motor.html
Brings the number of catastrophically failed engines (due to cylinder meltdown) I have encountered or inflicted to 5. With this comes an interesting trend I have found as to which cylinders are failing first...and in all 5 engines, it has been the back 3 cylinders of the passenger side (RH) of the engine, cylinders 3, 5, and 7.

The first engine I destroyed from overtemp had catastrophic piston failures on these same 3 cylinders. Cylinders 3 and 7 had holes burned either through the center or on the outside between the skirt and rings, and the cylinder walls. Cylinder 3 melted totally down until the point where the wristpin seperated from the piston on the exhaust stroke and crashed into the cylinder head. Next engine I damaged from this same issue was on cylinder 7 also, where the piston dome started to melt on the bottom outside corner and deposited aluminum plasma onto the cylinder wall and valve seats. Another engine likewise had dome damage to cylinders 5 and 7.

After getting our friend w00t's engine apart, cylinder 3 was melted to the point where some of the piston skirting and outside wall was actually deposited to the top of the cylinder wall at the head, and 5 and 7 had similiar damage to a less severe extent.

Seeing that from a statistical standpoint, 100% of the heat damage failures I have seen in a 6.0 engine are on the same three cylinders on 5 seperate engines, it brings me to take a hard look at what could be causing the issue. There are only a limited number of reasons that particular cylinders in this engine could run hotter than others, and this is what I have thought of thus far.

Fuel Delivery (combustion temperature)
-positive cylinder differential in fuel pressure
-positive cylinder differential in injection pressure

Volumetric Efficiency (combustion temperature)
-negative cylinder differential in intake charge
-negative cylinder differential in exhaust charge

Cooling deficiency
-negative cylinder differential in piston cooling jet flow
-negative cylinder differential in water jacket surface area and/or heat
absorption

Seeing that HEUI-style injectors don't rely directly upon actual fuel pressure to alter fuel delivery, I don't see that as the culprit; especially considering that if you look at the routing of the fuel lines, the passenger side head would be MORE likely to be starved for fuel than the drivers side head due to the longer fuel line. A change in injection pressure at the back of the passenger side oil rail causing higher fuel delivery in those cylinders is possible, because the stand pipe feeds fresh high pressure oil in at the back and the branch tube from the HPOP is somewhat (though minimally) shorter to the passenger side over the driver's side.

As far as airflow is concerned, a lack of fresh incoming air or restricted exhaust flow would both cause a cylinder temperature increase. Less airflow and positive manifold pressure to the back of the heads would make sense given the horseshoe shape of the intake manifold, but I can think of no immediate reason why there would be any difference between the RH or LH cylinder head given the relatively symmetric shape of the manifold. Exhaust restriction would be unlikely since the exhaust runners are symmetric across both heads, and the passenger side exhaust manifold actually has a less restrictive bend into the uppipe than the drivers side.

As far as cylinder cooling is concerned, water jacket flow could be a possible cause, but no cause for flow differential between the RH and LH engine banks is apparent. Cylinder wall overtemp would also result in scored cylinder walls and galling, which doesn't seem to be the case in what I've seen. What DOES seem to be the case is a direct issue of piston temperature, which is controlled by the piston cooling jet spraying oil onto the back side of the piston to remove heat. A negative trend of oil flow and pressure to the back of the RH bank would theoretically result in exactly what is being seen thus far, and leads me to believe it is likely the problem. Now assuming that it IS the problem, I'd like to know exactly why it is happening and a good fix for it.

I can think of a few things that could cause a drop in oil pressure to the cooling jets, but can't really nail down a specific reason. Do any of our resident techs or anyone familiar with the oil plumbing of the 6.0 know of a plausible reason for it?