To measure both the deck height volume and the piston dome volume, the piston is initially positioned 1 inch below the block deck. An O-ring is used in place of the top ring to form a seal. When ...

Strictly defined, compression ratio is the total volume above the piston at bottom dead center (BDC), divided by the total volume above the piston at top dead center (TDC). First, let's look at the ...

A revised test at 130°C aims to end off-season speculation — but could shift the debate into 2027.