I will post the data of everything when I get home. The engine is 9.0:1 CR and the wet intercooler keeps the IAT's down pretty good. I would think if it was going to act up it would have happened at 22 PSI and 18.5 degrees of timing on 73% ethanol.

 

At 9.0-1 I think you were ok at that timing level. I thought you were higher CR.

 

I run -11 cc wiseco pistons.

After doing the CR on a calculator it looks like I am at 9.16:1.

 

How does the cylinder look? If you need another piston, I still have 6 good ones I pulled out when I had my mishap.

 

It isn't too bad. I didn't inspect it real well. We're your pistons .030? It would be a K444X3 wiseco.

 

I am using the same piston in my new motor.

 

Can you replace just the piston and get a new head? Or is the cylinder bore damaged?

 

I'm hoping to be able to replace a piston and go. There were a couple nicks in the cylinder and I honestly didn't inspect it that we'll as it was late and I was tired. When I originally purchased the heads I never intended to be making this much power and had them milled for a boost in compression(back when I was supercharged). If I replaced a head I would have to geta CNC'd head from TSP. I think I will just go with a used set of 799's and do a little work by hand.

 

Yea with compression that low I think you were fine. If you had said closer to 10.0 I would have questioned it.

Do you know what springs you had on there? Any idea on their mileage? A little float on the exhaust side could have very easily caused this. Seems likely to me at this point.

here's to hoping its a quick recovery that only requires one piston and some heads

 

They are Brian Tooley Racing .660 titanium springs. I have about 3k miles on them. I turned the engine 7200 on the dyno last year with them. If I had to guess I think the engine let go at around 5900 RPM's. I didn't inspect to see if a spring was broke. If I had to guess by the looks of the piston it appears that valve floated and got broke off when it touched the piston. If there isn't a broke spring, I'm sort of at a loss. Maybe I'm thinking too much into it, but if a valve were to float wouldn't it be the intake valve? I would assume it is heavier, it has a shorter duration therefore it is opening quicker, and has boost pressure helping it open.