I'm trying to find out what works, and what doesn't. It's an L33, 9.95:1 CR, 799 heads, trucker cam, MP112 at 10-11 psi, likely to see 14-15 psi eventually. There's also a possibility of some nitrous later on, but probably with 10-11 psi.

Anyways, for stock pistons, and stock rings, on a stock bore diameter, what's a good ring gap? Mine are currently at .020", and here's the aftermath.




On a good note, everything else is in great shape!

 

?? This just happen recently?

 

Yep. Heard a piston speed knock on Wednesday at lunch, and parked it. We pulled it apart on Friday.

 

Bummer. Time to buy the pumpkin truck and start your project

 

Pumpkin truck guy won't return a phone call.....

Rod bolt question-- Service manual shows the rod bolts and main bolts are stretch bolts. In my experience, that means DO NOT REUSE. What have you guys been doing?

 

Damn! That’s too bad. I’d respectfully attribute your piston failure -at least partially- to its marginal cast hypereutectic design.
FWIW, .004” to .005” per inch of bore diameter is the rule of thumb for appropriate street upper ring clearance. You’re certainly in the ballpark.

BTDT going lean with an unhealthy dose of detonation/pre-ignition thrown into the 18-psi mix:



reference:
http://www.rosspistons.com/informati...stallation.pdf
http://www.jepistons.com/PDFs/TechCo...instrc4032.pdf
http://www.cppistons.com/LinkClick.a...Ls%3d&tabid=74

 

Broken ringlan is common with detonation but with mods listed you should use forged pisrons. Also the rod bolts are reusable, I have reused them on every engine I've done.

 

**** Roger that sucks.

Its just so common for 90% of guys here including myself to just throw in stock long blocks and boost em with bolt ons a good tune and have no problems.

But after the whole HotRod mag. 4.8 ring gap article it seems we start thinking about it, and it affected you, i say you had a freak incident.

So you just going to throw a new set of pistons and rod bolts in the girl and get her back on the road?

Your Radix is a bully, picking on poor 5.3 pistons ! LOL!

Any one know what ring gap spec is for the LS9 / LSA engines and what rod bolts they use? This might be a good route to follow.

 

How do the rings look? Ring ends show signs of touching?

 

What would that look like? I can post a pic tomorrow... but I don't know what I'm looking for.