Blew another motor

[ShadowBolt]

Run forged stuff if you like. It will not make you one tenth faster but something else is going on.

JJ

[Pranav]

Oh I won't...

[Rob Liebbe]

Can this be some form of harmonic/vibration induced failure?

[dtanker65]

I see what James was saying about it being difficult to diagnose grenade damage. Looking more like rod bolt failure if the damage to the 1/2 cylinder walls is from shrapnel behind the pistons as opposed to seizing. I would be looking for what is left of the rod bolts. My local machine shop re-uses rod bolts which I am not sure is a good idea for the rpm range we operate in. I have been doing research on fasteners since getting my Ford which uses quite a few one time use fasteners. The instructions for the ARP rod bolts I used on the last Windsor motor I assembled said they are re-usable if they are measured with a stretch gauge prior to removal and re-torqued to the measured stretch length. I think using new bolts is more important than the brand of bolts. You have no idea if a used bolt has been previously torqued past its yield point, if it has, it will fail. The coating on the new bolts is also critical to getting proper torque which is really bolt stretch value.

[marshall_mosty]

Can this be some form of harmonic/vibration induced failure?

Michael had a balancer go bad (Romac) and grenade a motor... can happen

[ShadowBolt]

Michael had a balancer go bad (Romac) and grenade a motor... can happen

If this is the same balancer on all the blown engines maybe you just found the problem? I did not know Michaels engine tore up like this one.

[mach1]

Michael had a balancer go bad (Romac) and grenade a motor... can happen

Did he just buy another one? What was wrong with the bad one?
I feel like my 302 is a time bomb because of the cast crank and 50oz imbalance hanging way out from the front main cap, that plus the fact I take it all the way to the limiter.

[Pranav]

Funny ya'll should say that, I have the same ATI Super damper balancer the entire time across all three motors.

My first motor was a used motor that I never built, just re-gasketed it and threw it in; we found pieces of a broken lifter in the pan during re-gasket job when I first got it, that should've been our first sign to send it off for a proper rebuild but I was young and dumb. It had a bad ring out the box, and very quickly spun a lifter during comp school. This motor had also just overheated too many times at every event, along with residual block/hole damage from the spun lifter, so I was not comfortable rebuilding it. Rotating assembly and lower bearings were OK however...

I only saved the heads/intake/pan off it for the second motor.

Second and third (this motor) was built by the same machine shop using a different short block, reusing the heads/intake/pan off the first motor. First time with stock bolts and Clevite P bearings, this time with ARPs and Clevite H bearings. On their first build, I killed the rod rear bearings that were going for some time (which I believed to be caused by 3 events worth of ignition issues, so I paid for the rebuild), and this time it was the front two cylinders and an instant failure with me doing everything by the book.

I am sending the balancer off to ATI as a preventative rebuild, or should I just get a new one?

I have talked to another engine builder that a number of you guys like, I think I will be working with him now. The current engine builder has a great reputation and I don't want to think this is any of their fault, but I have to take engine building out of the equation by trying someone else out if I decide to rebuild the longblock I am picking up tonight. This is particularly difficult as this builder is in my backyard, remembers everything I say, and is spot-on with service and getting stuff done on time. Maybe if we find the root cause and/or they cut me a break I may still give them a shot...

[AllZWay]

Seeing the pictures, I still think it was one of two things.

Broken rod close to the wrist pin that mangled the piston.
or a busted piston, but not from the valve since it doesn't look mangled. The head area looks like pieces of the piston were being beat between the top of the piston and head until the piston completely came apart.

Could a bolt or something have fallen through the intake onto the top of the piston?

[Pranav]

Hmm, I haven't had the intake pipe off since June I think. To recall I'm pretty sure it hasn't been off since the summer. I didn't see anything off about the backside of the throttle body and not sure if anything can come off/fall off inside the intake as it should just be solid aluminum all the way to the ports?