Summit Racing Cfm Calculator (2024)

FAQs

How to calculate how much CFM your engine needs? ›

CFM = ((Engine CID × RPM) × Volumetric Efficiency) ÷ 3456

Hopefully I did the math correctly, but even if I got it wrong, VE is not an easily-sourced figure. (Finding it might require an engine dyno to know the truth.)

An engine with a carb that is too big will put out less Torque and Horsepower . It will be difficult to drive due to poor low-end torque. If you drag race your car, an oversized carb will produce slow 60 ft. times.

To arrive at the most appropriate carburetor choice, there's a basic formula: engine displacement multiplied by maximum rpm divided by 3,456. For example: a typical 355ci small-block—a 0.030-over rebuild—with a 6,000-rpm max engine speed would work well with a 616-cfm carb ((355 x 6,000) 3,456 = 616.32).

CFM Formula

Use the formula below to calculate CFM: CFM = (Room Volume in cubic feet) x (ACH) / 60.

If you have a 6-cylinder engine then you'll need to be up in the 2,000 CFM range and for v8 engines, if you have a smaller cubic inch v8 2800 to 3000 CFM. For larger cubic inch of v8 engine you're going to be looking at 4500 CFM range, it can go up from there depending on the size of your engine.

How much CFM do you need per square foot? For general HVAC purposes, the typical recommendation is approximately 1 CFM per square foot of floor area.

As an example, a 750-cfm carb on one of my street/strip Chevy 383 small-blocks can make more than 600 streetable hp, whereas an engine less well spec'd may only make 540 to 550.

Take 350 ci multiplied by 5,500 maximum expected rpm equal 1,920,000. Then, take 1,920,000 and divide this number by 3,456 rpm and get 557 cfm, which calls for a 600-cfm carburetor if you're planning 5,500-6,000 rpm. If you're expecting a maximum of 6,500 rpm, you're going to need a 650- to 700-cfm carburetor.

The larger the space, the higher the fan CFM must be in order to efficiently cool a room. CFM for fans is a critical measurement for determining the right fan for your space. If the CFM is too low, the room will be unable to be cooled and undermine any energy efficiency of the fan.

No, the usual size on a stock engine like that is the 625-650 carburetor. (Carter calls it 625, Edelbrock says 650 – same carb). In fact, CFM refers to the maximum Cubic Feet per Minute of air/fuel mixture that a carburetor will flow.

Is Edelbrock better than Holley? ›

Our Overall Pick

Choosing between Holley and Edelbrock carburetors ultimately depends on your specific needs and preferences. If your vehicle primarily sees street use (more than 80% of the time), Edelbrock carburetors are our top recommendation due to their reliability and easy maintenance.

Typically for the size selection you need to know approx. horsepower (be honest). 600 cfm carbs best suited for low 300hp, 650cfm 340hp-390hp, 750cfm 400hp-460hp, 950cfm 490hp-575hp 1000cfm 575-595, 1050cfm-1250 600hp and up.

AIRFLOW. Air quantities (cfm): 400 cfm per ton of cooling is needed for normal comfort applications, 500 cfm per ton of cooling for heat pump and high sensible heat applications, and 350 cfm per ton of cooling for high latent heat applications.

This CFM calculator will help you determine the required air flow rate in CFM units for any room square footage and air change per hours, or ACH.

The engine manufacturer should specify the technical information required for this air consumption (CFM). When we don't have the airflow numbers, we can use the general rule of 2.5 times the horsepower of the engine to get an approximate amount of air required.

Calculating Air Flow ( Wa = HP x A/F x BSFC/60 )

Mass Flow Rate is the volume of air flowing through a compressor and engine over a given period. This is commonly measured as lbs/min of air flow. This calculation tells us the air flow we need to support our required horsepower target.

Engine Mass Air Flow Formula

To calculate the engine mass air flow, multiply the rate of fuel flow by the air-to-fuel ratio.

Gerr calculates the minimum total vent area in square inches for a passive ventilation system, i.e, no intake or exhaust blowers, by dividing total horsepower in the engine room by 3.3. He recommends adding 20 percent for most systems to make up for resistance from the ducting system.

If displacement is L cu. meters and rpm is R, you get L * R cu. meter per minute coming out of the engine if it's a 2 stroke, L * R/2 if it's a 4 stroke. In order to determine, exhaust gas flow rate in mass or volume, the formula for total mass of exhaust gas is m_a (mass of air)+ m_f (mass of fuel).