Alloy LS-1 series Chevy V8's like the ZO6, the 5.7 and 6.0's, are postive deck engines from the factory.
Over 9 thou of the piston pokes into the chamber. Yeah, its a dished piston for sure, but the edges of the piston block the hot anular wall of the cylinder walls at maximum squeeze, and rise right into the 27 thou gasket. Chevy engineers discovered mixture motion and spark flame travel could be effectively managed like this, with the abilty to run very efficent combustion process.
It looks like this is the ideal if you are able to ensure there is at least 15 to 30 thou distance from the open valves if something horible, like cam chain failure happened. Mopar B and 426 Hemi-engine guys have been doing it for years at the drags. Setting the bump (cylinder to valve clearnance at top dead centre) is both a diesel trick and a rather sad consequence of the 426 Hemi combustion chamber. It is time consuming job wet building up each rod and crank journal with a blue printed piston of a stock deck height, and then adding as much plasticine to the top of the piston until you can run the piston right into the compbustion chamber. The cam has to be fitted, the valves, the steel shim or copper gasket and then everything checked, and then disassembled again if the plasticine gets hit by the exhast or inlet valve.
Finally, the pistons are blue printed and the final amount of deck height on the block can be decked down to get the ideal amount of piston bump.
I'd say there are 20 influences into detonation, but having the best piston deck would give a 1 to maybee 5% help to getting a high compression ratio to work on the street, if you were fastidious drag race prep detail freek . All Detriot engines have tended to stick to 25 thou below the deck, and zero deck production engines were really rare because of rod stretch at maximum revs. This can cause a large cracked piston if the anular region around the piston hits the quench area of the head. Even the Boss Cleveland 351 with 11.7:1 compression had a 16 thou below deck piston!
To ensure a zero deck 200 or 250 engine never comes to grief via vlave or piston contact, the piston would have to be machined back to ensure it never comes within 45 thou of the head and valves under maximum revs. Rods can grow up to 30 thou under load. That kind of detail costs a bucketload of machine engineering and process engineering time. This was impossible for Detriot to do until the advent of totally new engine plant tooling.
Chevy do it from the factory, and its just one of the many reasons the car can run huge compression ratios with rich air fuel settings without detonation.
