So pulled my motor apart after I had noticed some blue smoke and loss of compression in one cylinder..this is what i found. All 4 pistons are the same.. its the intake side of the valve....sleeved H22 motor...professionally tuned motor making 300hp at 16psi..the motor was recently built with maybe a thousand miles and was properly broke in.

What do you think happened?

 

were you running to much nos.

 

Did you give the motor time to break in after it was built? You say it was only 1000 miles old.

 

detonation looks like a big factor. what octane gas were you running and how conservative was your tune?

 

hmmmm ,i say either the pistons where installed upside down or you had a valve train issue ,mainly a spring problem

 

i'd have to say detonation

 

94 octane and air/fuel is always between 11.3-11.8... i also have a wideband installed...i do think it detonated...but after the pistons broke apart..

 

how do the valves look ?

 

Looks like things got really hot!!!

 

The dark tops of the pistons makes me think it was burning some oil. The marks on top of them kinda looks like detonation, or maybe just parts of the pistons as they broke apart and went into other cylinders.
How do the valves look? Any contact marks?
Weird how all the pistons broke in the exact same spot. Maybe defective pistons?
Are they CP pistons by chance?

 

yes they are CP...how did you guess??...the head is fine... alittle bit of piting from pieces of piston bouncing around in there, but it doesn't look like the valves were contacting the piston.

 

I saw another build do something similar somewhere on here...No apparent cause and all the pistons had the same damage.
If you inspect where the piece broke off, youll see what I believe is not enough material in that intake valveseat area.
Should have designed another .100" into the bottom side, IMO...

 

It's obviously a piston design issue (i.e. atrociously bad piston design). Look how close the corners of the valve recesses in the crown come to the top of the ring groove, very little metal there (you can see this clearly in the 3rd pic from top). The valve recesses are either too deep or the top ring groove is too high. Never use this brand of piston ever again...

I'd be presenting these pistons to my supplier for a refund, and I'd be after a free rebuild too if I could twist arms hard enough.