I’m kinda surprised that nobody agreed nor disagreed on my post regarding the lifter bleed down potentially leading to it’s demise. If you have aeration going on and lifters are bleeding down wouldn’t that potentially throw off geometry and possibly causing the failure of?

Looks and sounds like Dan’s taken about every precaution on reducing aeration to a minimal along with having the ideal components to stabilize his valvetrain.

So many factors that could lead to failure. It’s nearly impossible to fully determine by looking at wrecked parts.

Lifter mass, valve train natural frequency, hydraulic lifter pump up and leak down.

At some point we’ll just be reaching the material property limits of trying to put 600lbs force through a .842” wheel.

Piston update

jb weld and a polishing wheel =,good to go.

what cylinder was that?

5?

Looking at everything here. My thoughts are the real problem being your running this engine as batch fire for the fuel injectors through the throttle body. I've been through this before. You should change the intake manifold the make it port injection. the problem with batch fire injection is the front cylinders get all the fuel on a whipple set up and the back ones get leaned out. Tough to read off an O2 sensor. Only can really see it on a dyno watching EGT's. Whipple sells a manifold with port injection now. In the past I had to modify ones to make it work.

Is that the intake side of the piston. Looks like detonation. Or combo!

I’d agree Dan should go port injection and skip the TR’s. Sell those to me! I’d imagine he might do both though. 😊. Also what’s the ground strap look like on dat ho?

Quote "Tough to read off an O2 sensor. Only can really see it on a dyno watching EGT's."

Even watching the EGTs per cyl it can happen in the blink of an eye

So very true on the the fuel distribution and more so on a Marine Endurance set up!

Seen it happen in recent years! with a seasoned dyno expert melting pistons down!

Just my 2 cents for what its worth

#5 and 6 on both engines .
You can see the heat at the bottom of some of the pistons (burned oil), others are like new.

Ive learned not all gas stations are the same , if it`s not top Tier fuel it`s kinda junk and more prone to detonation.
https://www.toptiergas.com/

Secondly, my effective compression with todays fuel is too high (engine builder opinion) with 10psi. My engine builder says at 6psi it`ll live a good long life, 8 psi on the edge , 10 psi better use race fuel.(14-1 compression no bueno)

add into that a tight wall to piston clearance .045 one engine .055 the other , no room to grow.
add to that I leaned it out to 12.5 afrs at 4000rpm and 32* of timing. My other tune was 28* and low 12s .... and here we are .
Time to put a passcode on my laptop so I stop messing with stuff.

The new engine builder is very detail oriented. Hopefully that helps.