It's all fun and games until someone burns a piston...

[ijames]

How about the ring end gaps and the piston-bore clearance? Any chance something started to bind up and made a bunch of heat? Any signs of burnt oil on the plug before the meltdown? Bad ring seal or maybe bad guide/guide seal and oil in the cylinder and detonation and and ... .

 

[TurboBuRick]

Looks like the far edge of the piston has some dents. When I think abuot it the valves would not hit there if they did get smacked but why the dents?

No doubt about it that sucker got HOT!

Do you have a data log from that run?

 

[DR BOOST]

i burned a piston exactly like that when my alky pump started going south. on a fast car make sure the alky tank is filled to the top because a hard launch will uncover the pickup.

 

[disco stu]

Gap, .019 top, .020 bottom, leakdown less than 5 percent, piston bore clearance fine.

Those pistons had valve reliefs. No valves touched anything. Car made plenty of dyno pulls and 1/8th runs.

 

[vacuum 6]

Sorry man. Let us know your findings.

 

[ijames]

Only other thought is that the methanol injection might be having distribution problems? Normally without alcohol injection the back cylinders get the most air so tend to run lean. With methanol and wet flow it might work the same way, with the back cylinders getting the most methanol and the front cylinders getting starved. Just a theoretical thought, no hands-on testing to back it up. What manifold, upper plenum, what mods, power plate, where are the methanol jets (you know the list of questions to ask )? Sure hope you find it.

 

[turbo6randy]

Stu
I had the same thing happen at the GS Nats this year, but mine burnt the piston and cracked the block. Usually run mine 1/8 mile with no problems but the 1/4 is a different story. May have to start using race gas for the 1/4.
Like you I suspect a fuel supply issue but I opened my ring gaps a little also just incase.
Randy

 

[murphster]

I had a similar thing happen to me earlier this year. Melted the #1 plug and scorched the piston. The same thing happened at the end of last year, but I was on a single pump then and it melted through the head instead since there was some excess sealer on it and it provided an easier path. Repaired the head and upgraded to a double pumper and then the plug melted.

I flowed the 83# injectors and they were all good. I was running a champion fuel rail with an inline accufab regulator, stock fuel lines, Precision plenum and a power plate. After playing with other cars over the summer, finally upgraded to -8AN line from the double pumper and then split it to dual feed both rails. I got an external regulator about a foot off the rail and am using the stock fuel line as a return. Hoping this will fix the problem. Talking to other people and reading a lot it seems like the #1 becomes a problem with single fed rail/inline regulator setup for some, but not all, at these power levels.

While I don't have a multiple EGT setup, everything looked fine and no knock and good EGTs until the problem hit. Also running pump gas and alky. Maybe with alky any problems with an inline regulator are magnified. Will be posting some pictures of my setup soon.