C409

..... Did a compression ratio adjustment at the track ... gonna head out to Walmart to pick up some JB Weld .....

PatternDayTrader

Lol ..

Tom400CFI

You got variable compression on that thing? That is quite the nice radius on that top ring!

tpi 421 vette

Wow, that sucks. Looks like it went lean.

JCrock

Bah! Amatuer!

383vett

Ouch. The run before this must have been quick! Block ok?

C409

..... Not too quick , I ran a 6.80 on the eighth ... this setup usually runs 6.76's ... my front brakes have been dragging a bit (now I have time to rebuild the calipers) and I thought that might have been what slowed me down ... anyway , the block cleaned up @ .0015 ... time for some custom pistons ... .....

C409

..... Still scratchin' our heads ... the datalogger showed the AFR on that bank @ 12.5 through the pass from 4500rpm up ..... and the spark was 2 degrees lower than I usually run ... I'm starting to think it was too fat .....

C409

..... ... Nice ! .....

C409

..... I lost 13.4:1 in a hurry ! .....

PatternDayTrader

The first thing I thought when I saw that pic was a foreign object of some sort was ingested by that cylinder ...

C409

..... Nothing extraneous here ! Foreign objects leave witness marks in the piston crown and the cylinder head ... this was a torch job ... arson , I tell you ! ... You can see how it melted through the oil ring and the oil ring support rail , not to mention the aluminum piston .....

PatternDayTrader

Yeah the crown looks damage free. At least free from foreign material type of damage.

1985 Corvette

Wow that sucks, Bob but you're not wasting any time getting it back together for more runs. A true gearhead! I'm curious to know how this happened if your readouts logged showed everything in tolerance.

C409

..... Top View .....

C409

..... Another angle .....

PatternDayTrader

Oh yeah that's unmistakable. Its just melted away ...

bjankuski

Definately detonated, I assume this car if fuel injected, I would look for a problem with that cylinders fuel injector. (Did the WB monitor a lean condition and add fuel to the other three cylinders while this one was still lean)? Was your water pump working on the run, (Hot spot like a steam pocket)?

C409

..... Hey Jamal ! ... The car launched normal ... 1.47 60' , had a little air under the fronts , but by half track I knew it was losing power and when I got off the pedal it smoked like 2 or 3 people vaping ... everyone was surprised that I drove it back to the pits ... the safety crew expected to see a couple of rods hanging out of the block ... by the time I put it on the trailer , it was wheezing oil and fumes out of both valve cover breathers ... thankfully , it started up when I got home so I could put it in the garage ... Gotta get it back together , this is our racing season ... the tracks shut down in July and August because of the weather ! .....

PatternDayTrader

That would do it. Lean mixture leads to combustion temps that are to high, which leads to a deformed piston, which leads to a stuck ring, which leads to blowby, which leads to the oil being burnt off the cylinder wall, which leads to metal transfer, which leads to the pictures above, which leads to new pistons. Therefore fords are junk and the c4 wins.