1. What is a Compression Ratio Calculator for SBC Engines?

Definition: This calculator estimates the compression ratio of a Small Block Chevy (SBC) engine based on swept volume and clearance volume.

Purpose: It helps engine builders and automotive enthusiasts determine the compression ratio which affects engine performance and fuel requirements.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( CR \) — Compression Ratio (unitless)
• \( swept \) — Swept volume (cc)
• \( clearance \) — Clearance volume (cc)

Explanation: The compression ratio is the ratio of the maximum to minimum volume in the cylinder.

3. Importance of Compression Ratio

Details: Compression ratio affects engine efficiency, power output, and fuel requirements. Higher ratios typically mean more power but may require higher octane fuel.

4. Using the Calculator

Tips: Enter the swept volume (displacement per cylinder) and clearance volume (combustion chamber volume plus gasket volume plus piston dome/dish volume). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical SBC compression ratio?
A: Stock SBC engines typically range from 8:1 to 10:1, while performance builds may go up to 12:1 or higher.

Q2: How do I measure clearance volume?
A: It's the sum of combustion chamber volume, head gasket volume, and piston-to-deck volume (including any dome or dish).

Q3: What's the relationship between CR and octane?
A: Higher compression ratios generally require higher octane fuel to prevent detonation.

Q4: What's a safe CR for pump gas?
A: For 91-93 octane, typically 10.5:1 is safe with proper tuning and quench.

Q5: Does this calculator work for other engines?
A: Yes, the formula works for any piston engine, though values are optimized for SBC applications.