Darren - good to hear you're enjoying that combo. I honestly had no idea anyone here was using it. As for the piston to wall clearance, everything I've read suggest the 85.5mm (.020).
Why go bigger?
What are the advantages?
Ghislain - I had always thought the higher CR gives you a more torquey low end, but limits your max psi from a turbo. What turbo do you use?
Since you typed .020, I'll assume your talking about the pistons being .020 larger then stock? This is the piston size, not the PTW (piston to wall) clearance. Yes, typically get a .020 over piston, this allows them to bore the cylinder to the proper PTW clearance. That is, unless your cylinder bores are bad & require an even larger oversized piston.
At one time Wiseco use to spec something like .0020 PTW for our applications, way too tight. Under the boost/power you plan to make, pistons will be eating cylinder. Think they recommended something like .0030 or .0035 for big power back when I had my engine built. Still too tight from everyone I spoke to. Piston slap is more so to do with piston design (yes, with excessivly big PTW you can get slap as well), but .0040-.0050, is not considered excessive & should be quiet, even on startup. Believe one guy was running .0060 & still quiet on startup.
I had my work done by Gord as well.
