2011 piston failure diagnosis discussion w/pics

[VET-KLR]

Must be kansas city luck.....the coyote in my 2011 f150 just blew....bone stock......4400 miles. I personally dont thinks these motors are all that great in my opinion. My 2012 gt was ok......sold it to buy a tow vehicle for the new race car. What a nightmare this turned out to be lol. Good luck on the rebuild.


Ricky

At least that one will get fixed under warranty. Sucks to hear. I would like a newer F150 but probably go ecoboost.

 

[DILYSI Dave]

Those tops look fine. I'm guessing detonation causing shock fracture, rather than a lean / heat related failure.

What fuel were you running?

 

[VET-KLR]

It was 93 octane pump gas.

 

[DILYSI Dave]

11:1 + 10 psi is A LOT to ask out of pump gas. Your AFR's could have been dead on, and still had detonation simply because the octane isn't high enough for the cylinder pressures you're seeing. I've done 11.7:1 + 10 psi, but I also was fueling with E85.

My gut feeling is that this one comes down to that fuel.

 

[RSKtakR]

I helped pull this motor apart, and the tops of all the pistons looked great just like a 7500 mile piston should, plugs looked good (except for the 3 that failed). There was a pretty good sized pile of shit that was in the oil pump pickup. I couldnt believe the chunks of rings and pistons that came out of there lol. As stated before this was never called a "#8 issue" and as you can tell by the pic's it wasn't.

 

[killswitch_c]

Dam that sucks man

 

[wproctor411]

I helped pull this motor apart, and the tops of all the pistons looked great just like a 7500 mile piston should, plugs looked good (except for the 3 that failed). There was a pretty good sized pile of shit that was in the oil pump pickup. I couldnt believe the chunks of rings and pistons that came out of there lol. As stated before this was never called a "#8 issue" and as you can tell by the pic's it wasn't.

Wow. I think you guys found the limit for 11:1/10psi/93 octane on stock parts. I've seen similar happen to a set of forged pistons as well. Everything has a limit. I'm guessing you were close to 800 crank HP at 10 psi.

 

[VET-KLR]

I also could've got a bad tank of fuel I suppose.

 

[SS KILLR]

Wow. I think you guys found the limit for 11:1/10psi/93 octane on stock parts. I've seen similar happen to a set of forged pistons as well. Everything has a limit. I'm guessing you were close to 800 crank HP at 10 psi.

Wow. I wouldn't have thout by the sound if the mods you where over 625-650

 

[wproctor411]

Wow. I wouldn't have thout by the sound if the mods you where over 625-650

You may be right. I was just looking at KB kit that was 675HP at 8psi on EVO's website. I'm talkin engine crank HP not wheel power. Either way that is a lot of power for stock GT parts.

 

[VET-KLR]

It was supposed to be 600rwhp or so. Never got to the point of dynoing. That will happen soon on new setup. I'll discuss fuel with my tuner.

 

[Scuba-Matt]

What was the MAF count ? Wondering if you pegged the MAF. Looks like a shock wave from detonation killed the cast piston. Do you have pic's of the plugs and heads?
Sorry to se this happen to you.

 

[VET-KLR]

I didn't have MAF count as an option to log. I don't have pics of heads or plugs but both looked fine. The heads looked like new and the plugs all looked good except the couple that were oil fouled.

 

[KenB]

FYI, 2011+ have a frequency based MAF, not measured in counts.

 

[Greg Hazlett]

Not to thread hi jack but I guess that makes MAFia's obsolete for the 5.0's?

What option do the 5.0's have then when "maxing out" their MAF's or is that not an issue with a frequency based MAF?

In laymans terms what are the differences between the MAF count way and the frequency way?

 

[VET-KLR]

I did have a frequency option that was logged.

 

[Scuba-Matt]

FYI, 2011+ have a frequency based MAF, not measured in counts.

I just learned something new.

 

[Bryan]

Damn sorry that your engine went south man, that sucks. What shortblock did you go with? What tool are you using to monitor knock?

I feel for ya man, been down this road many times with my v6 turbo engines


What was weak is now stronger

 

[VET-KLR]

2012 Boss shortblock. No tool to monitor knock. Datalogging and dyno tune happening soon. I have just over 1000 miles on it now and have taken it fairly easy.

 

[jaguarking11]

Seems like its more likely related to harmonics. The pistons would have pitting and burned off edges if it was detonation. First thing I thought to myself, wonder what the tops look like.

IMHO this was not due to fuel, or detonation. It was due to harmonics, how fast was it spinning when it blew? What gear? Did you power shift it? Or if an auto did you firm up shifting? Again harmonics and maybe shock loading. Fuel cut off? Detonation usually chips the face first, right around the valve releifs and the edges of the top. Usually it takes chunks out the heads too.

I could also be way off base here, however in the past I have seen engines that were built blow to shreds because of harmonics, especially with the size of the piston in relation to length. For all intensive purposes the 5.0L engine has bad geometry for high revving, but the factory does it. For that matter so do ls7's. I do feel the harmonics of this engine are quite different from my previous 3v engine. The 3v was rougher at idle to around 2800rpm, then it smoothed like butter until 6800rpm where my rev limit was. The 5.0 is rugh from idle to 1500rpm then it smoothness out to about 5500, after that I can feel some bad harmonics, however the engine is so much more eager to rev that its hard to judge exactly the cut off.