CH Calculator
This calculator lets you test piston + rod combinations against a target deck height. It automatically calculates deck clearance and displacement.
Deck Clearance: in
Displacement: CID
→ Go to Compression Ratio & Displacement Calculator
📘 Theory
- Deck Clearance = Deck Height − (Rod Length + Stroke / 2 + Compression Height)
- Displacement = π / 4 × Bore² × Stroke × Number of Cylinders (default 8)
- Negative deck clearance means the piston is above the deck surface — this can cause mechanical damage.
📐 What this tool does
- This calculator lets you match piston compression height (CH) to your deck height, rod length, and stroke.
- The goal is to reach a safe and optimal deck clearance.
- If the value becomes negative, the piston will protrude above the block deck — this usually means the CH is too high or the combination doesn’t fit without machining.
- Typical clearances:
0.000" (zero deck) for high-performance builds
0.030"–0.050" for most street/strip engines