LBZ cracked piston - What long block to with ?

[OleBlackyLBZ]

I seen in a post from Jon/Fingers, that high cylinder pressure and big fast temp swings is what kills cast pistons. So here we go again, really aggressive tuning could probably kill race cast pistons at 900-1,000. Where as if you went a little heavy on the air side with some-what conservative tuning down low they would probably live at that power level for a good long time. Same with my New de-lipped lb7's, I'm running lbz rods so Mark is conservative with my tuning, on that set-up I'm betting I could get some real good life out of the de-lipped lb7's.

 

[OleBlackyLBZ]

I know Verlon that worked for Idaho Rob back in the day cracked a de-lipped lb7 piston at 650hp with compounds and injectors. But he was towing and pulling hills at wot on the big tune. I don't think he had an oil temp gauge so really high oil temp could have definitely played a role in that piston failure. I think that was back before the realization that two turbos raised oil temperatures.

 

[NevadaLLY]

I'm just wrapping a build from a cracked OEM LLY piston - I went with the Mahle Performance Cast pistons .020 over with the coating from SoCal. It'll be running with wagler rods, compounds, 100% overs, and a 12mm stroker S&S. I also upgraded to a 3388 CAM. It's mostly a tow pig but I'm expecting 100k out of this build. I don't plan to go much past 800 on the hot tune but will love to throw it on a Dyno one day to see what it's putting down. The performance cast take .010 of the CH and with the 100% over's, cylinder pressure should be better than the OEM setup. Also, I've lowered drive pressure with PPE manifolds, up-pipes, and a Stage 3 64MM turbo. I think this is going to be a great setup. From an Oil temp perspective, I also threw on a 2020 L5P oil cooler, heat wrapped the pump-cooler water pipe (a lot of people said don't worry about it but I was already there so why not?? ) but also have an external oil cooler up front. I'll keep everyone posted if I have any piston problems but I really think this is the ideal street/tow build with a side of fun.

 

[OleBlackyLBZ]

I'm just wrapping a build from a cracked OEM LLY piston - I went with the Mahle Performance Cast pistons .020 over with the coating from SoCal. It'll be running with wagler rods, compounds, 100% overs, and a 12mm stroker S&S. I also upgraded to a 3388 CAM. It's mostly a tow pig but I'm expecting 100k out of this build. I don't plan to go much past 800 on the hot tune but will love to throw it on a Dyno one day to see what it's putting down. The performance cast take .010 of the CH and with the 100% over's, cylinder pressure should be better than the OEM setup. Also, I've lowered drive pressure with PPE manifolds, up-pipes, and a Stage 3 64MM turbo. I think this is going to be a great setup. From an Oil temp perspective, I also threw on a 2020 L5P oil cooler, heat wrapped the pump-cooler water pipe (a lot of people said don't worry about it but I was already there so why not?? ) but also have an external oil cooler up front. I'll keep everyone posted if I have any piston problems but I really think this is the ideal street/tow build with a side of fun.

What did it take to crack the LLY piston?

 

[NevadaLLY]

What did it take to crack the LLY piston?

It could have been remnant damage from hills during the drive but I was towing in my tow tune, flat ground for about 30 min cruising easy and boom white smoke, loss of power, shuddering, and puking oil out of the PCV. My guess is the piston, with stock compression, and a suspect injector was the culprit. There was evidence of advance timing and I was on stock injectors so that could have been it as well. The tow tune is very mild so I was leaning more toward a stuck open injector. I was having some hazing during startup but it was winter so I had thought it was just temp related. Egt’s were always controlled and never run past 1200-1250. I went big and new on injectors to take both question marks out of play. Also coated the piston to help with heat protection for those heavy pulls for 10miles up 7% grades with a 20k load.