Ford Truck Enthusiasts Forums - My Theory on cause of 6.0L failure

Ok, we'll start this from the beggining and explain it.

My truck was a 2006 F-250 6.0L with the following mods:

Jobe Performance Intake
Banks Techni-Cooler
ARP Head Studs
Stock Ford Head Gaskets
Bean's 225cc Injectors (Stage II)
Return Regulated Fuel System
Pro-Street 64 Non-VGT Turbo
4" Downpipe to 5" Straight Exhaust
FASS 150/150 Fuel Pump
FS-2500 Oil Bypass Filter
Precision Industries Torque Converter
FluidAmpr
Nitrous Express NxD Stacker System
Snow Performance Stage III Water/Meth Injection
SCT xCal2 Tuner with Extreme Tunes by Eric

With the above mods, she was putting down very close to 700HP to the ground.

We took her to the drag strip and made 3 passes that were very poor due to the fact that I hadn't had any practice getting the turbo to spool up.

On the fourth pass I really wanted to see what she could do with everything she had. I spooled her up to 6-8 pounds at the staging light, which was not quite enough, but it's all she'd get before the lights. I punched her on the third yellow and got a very good reaction time. At apporoximately the 60', I turned on the NOS and then the Water/Meth, which was set to Boost Only activation. She pulled so hard on both that I could hardly hold her straight! At about 1/2 track, she shifted into either 3rd or 4th (I couldn't keep up with it) and then, she started to make a gear on gear noise like a blower whine. I saw the oil pressure drop to zero, but really didn't compute what that meant. At this point, I think she was still running. At about 2/3 track she totally gave out and began to coast. I pulled off the track at the end and she was dead.

1.) So, what happend?

She over reved to 4500-4600 RPM's and then shifted. This way overstressed the LPOP gears (which was the nose I heard) and they broke cutting all the oil. So that's the cause of the gear failure, IMO. I don't personally believe that the FluidAmpr affected this as I think even with a stock dampner they would have gone at this RPM.

2.) But why did she overrev if the programming defueled her at 4000 RPM's for the shift?

Simple, the #2 fuel was cut, but the Water/Meth and NOS were still flowing full on and giving her fuel to burn. Enough so she couldn't shift. When she reved high enough to give out, she shifted.

3.) So what blew the turbo then?

The EGT's were at around 1700* and the oil, that cools and lubricates the high RPM vanes of the turbo quit. So she was spinning dry and very hot. Also, the boost was near max around 36-38PSI. That boost had to exit somewhere, so it went back out the intake thus backspinning the turbo. It went from spinning 100K RPM's one way, to 100K RPM's the other way. The two together would take the bearings out in a hurry.

4.) So why did the engine come apart so long after?

Well, I cranked her several times at the end of the track trying to determine the issue, so the bearing didn't get a chance to lock up there. Then we go her running a couple days after, but she had quit dry of oil and most likely the oil took a bit to get flowing after the restart, so she was run dry and hot. After the no boost discovery, we had to shut her down another couple days to swap out the turbos. Once that was done and she ran again, we got on a main road and built a bit of boost that was enough to blow out the already very weak bearings. So she put a rod through the block.

5.) What do we think we need to do to prevent this issue again?

DON'T SOUP IT UP AND RACE IT! ROFL

6.) Ok, well, that ain't gonna fly, so now what?

a.) First issue I'd look at is a window switch on the NOS AND the Water/Meth. They need to cut off around 3800-3900 RPM to allow for the shift. They should also both be progressive so they don't hit all at once after the shift, but come on gradually.

b.) Second issue is the durability of the LPOP. There's really two ways to go about this issue. One is fairly inexpensive, but possibly less reliable.

i.) The inexpensive fix might be to clearance the stock gears. This would involve radiusing the outer sharply machined edges front and back. Then shaving just under a thousandth of an inch off the teeth on either the inner or outer gear. This would reduce the chance for binding if the gears started to float. There are hardened H-11 gears out there that would be stronger to replace the stock gears, but IMO, I think that could hurt other things. If those gears were to bind as the stock ones, what would happen to the crank? I'd rather lose the gears then the crank. Of course there's also, I lost the gears and still lost the crank. I did say this was all theory.

ii.) The right way, IMO, would be to develop and external belt driven LPOP that could handle the added stress. The gears are subject to issues with crank deflection at higher RPM ranges. This makes them more prone to binding and breaking. An external oil pump would eliminate this added problem.

So, when money becomes available again in the future for me, I plan to start thinking things through after learning from my latest lesson. I need to resolve oiling issues and not rely on the chemicals.