The Summit CFM Calculator is an invaluable resource for anyone looking to optimize their engine’s performance through precise airflow calculation. It helps in determining the required cubic feet per minute (CFM) of air that an engine needs to operate efficiently. By calculating the ideal CFM, users can select the appropriate carburetor size, which is pivotal for achieving maximum power and efficiency from their engine. This tool is essential for both amateur and professional mechanics, as well as automotive enthusiasts who aim to tailor their vehicle’s performance to either street or racing standards.
Formula of Summit CFM Calculator
The Summit CFM Calculator employs a simple yet effective formula to calculate the desired CFM:
CFM = ((Engine CID × RPM) × Volumetric Efficiency) ÷ 3456
Where:
CFM– Cubic Feet per Minute (desired output)Engine CID– Engine Cubic Inch Displacement (engine size)RPM– Revolutions Per Minute (engine speed)Volumetric Efficiency– A percentage representing the efficiency of your engine in filling its cylinders with air (estimated values: 85% for street, 110% for racing)
General Terms and Conversion Table
| erm | Definition/Value |
|---|---|
| Cubic Inch Displacement (CID) | The volume displaced by all the pistons within the cylinders, measured in cubic inches. |
| Revolutions Per Minute (RPM) | The number of turns the engine crankshaft makes in a minute. |
| Volumetric Efficiency (VE) | The efficiency with which the engine can move the charge of fuel and air into and out of the cylinders. |
| CFM | The volume of air flow per minute that the engine requires to operate efficiently. |
Estimated Volumetric Efficiency Values:
| Application | Volumetric Efficiency (%) |
|---|---|
| Street | 85% |
| Racing | 110% |
Conversion Factors:
- Cubic Inches to Cubic Centimeters: To convert cubic inches (CID) to cubic centimeters (CC), multiply by 16.387. For example, 350 CID * 16.387 = 5735.45 CC.
- RPM Levels: Typical street engines operate between 2,000 to 7,000 RPM, while racing engines may exceed this range.
Example of Summit CFM Calculator
Consider a street-tuned engine with a displacement of 350 cubic inches, operating at 5,000 RPM, and with an estimated volumetric efficiency of 85%. Using the formula:
CFM = ((350 × 5000) × 0.85) ÷ 3456 CFM ≈ 429
This calculation indicates that an engine of this specification requires approximately 429 CFM to operate efficiently, guiding the selection of a suitable carburetor.
Most Common FAQs
Volumetric efficiency (VE) measures how effectively an engine fills its cylinders with air. It directly impacts CFM, as higher VE indicates more air-and-fuel mix can be combusted, potentially leading to increased engine power. VE varies by engine design, modifications, and operating conditions.
Once you’ve calculated the CFM, select a carburetor with a CFM rating that matches or slightly exceeds your engine’s requirement. For street applications, a carburetor that closely matches the calculated CFM is ideal, while for racing, a slightly higher CFM rating may provide better performance.
Yes, the Summit CFM Calculator is versatile and can be used for a wide range of engine types and sizes. However, it’s crucial to input accurate values for displacement, RPM, and volumetric efficiency to ensure reliable results.
