Redcoupe,
I agree the clutch pressure plate diaphragm failure is probably unrelated to the engine detonation.
The engine builder is a small shop and dedicated to classic Porsches. Clean environments and meticulous methods are the currency of their reputation, however we will hopefully soon find the evidence we need to verify these failure causes.
I also don't believe the engine was overstressed.
The Eurospec version of this motor came with a 10.2:1 single plug design.
Porsche made & still makes engines that run at 11 or even 12 to 1 compressions.
This engine was built to accommodate a slightly higher than standard compression ratioat 11.2:1, but other than that everything else is an over the counter bolt on modification. By all accounts the engine work is a fairly mild modification and 255HP is not such a volatile stress that the motor should detonate after 11 000miles of sensible/informed use.
Investigation is definitely needed to get closer to cause, which will also ultimately help clarify any potential cost sharing.
My opportunity is to decide if I go back to a standard configuration, or if I use the unfortunate circumstance to build a different bottom end, since the top of the motor is ready for a high flow, twin plug configuration.
- Standard 3.2
- Higher compression 3.2
- Standard compression & increased displacement (3.4 or 3.5)
- Higher compression & increased displacement