Definition of "CFM"

85_SS_302_Coupe · Apr 15, 2005

It dawned on me the other day that i don't know exactly what "cfm" stands for, so now i feel completely noob I've looked around and all i can find is some serious physics type definitions that i barely understand, mainly "contraint force mixing"....is this the right definition or am i going off on another path?

squeeeg · Apr 15, 2005

I think it is cubic feet per minute

Insane3D · Apr 15, 2005

squeeeg said:
I think it is cubic feet per minute

That's how I've always known it...

85_SS_302_Coupe · Apr 15, 2005

squeeeg said:
I think it is cubic feet per minute

Yea that's what i had guessed but then i got all this constraint force mixing crap and it totally threw me off. And then i read that cubic feet per minute is an assumption....

TheBocSez · Apr 15, 2005

85_SS_302_Coupe said:
Yea that's what i had guessed but then i got all this constraint force mixing crap and it totally threw me off. And then i read that cubic feet per minute is an assumption....

I think it would be an assumption. Using a carburator as an example, it assumes that a 600cfm carb would draw 600 cubic feet per min of air is left at wide open throttle for 1 minute but there are too many factors that can affect the carb to include air density. Now I may be totally wrong on that statement but if you read it, it sure does sound smart!!

5spd GT · Apr 15, 2005

Yeah it's cubic feet per minute which is a standard measurement of airflow that indicates how many cubic feet of air pass by a stationary point in one minute.

According to a definition "1 CFM equals approximately 2 liters per second"...but wouldn't that be 1200 liters of air in a second with a cfm of 600 (carbed example)...seems a bit high to me

Car RamRod · Apr 15, 2005

Insane3D said:
That's how I've always known it...

me too

HISSIN50 · Apr 15, 2005

and if talking about fan draw, note that the procedure used in measuring makes a world of difference (a better flowing fan can show poorer relative flow numbers than an inferior fan simply from different testing protocol).

Ordie · Apr 16, 2005

5spd GT said:
Yeah it's cubic feet per minute which is a standard measurement of airflow that indicates how many cubic feet of air pass by a stationary point in one minute.

According to a definition "1 CFM equals approximately 2 liters per second"...but wouldn't that be 1200 liters of air in a second with a cfm of 600 (carbed example)...seems a bit high to me

that would be 1200 liters per minute not second...

5spd GT · Apr 16, 2005

Ordie said:
that would be 1200 liters per minute not second...

If 1cfm equals 2 liters per second...and you put the 600cfm in place of the 1cfm you would multiply the 2 liters by 600 which would be 1200 liters per second...

mackey · Apr 16, 2005

5spd GT said:
If 1cfm equals 2 liters per second...and you put the 600cfm in place of the 1cfm you would multiply the 2 liters by 600 which would be 1200 liters per second...

How does 1cfm equal 2 liters per second. Please link me to the source you got that from. That is wayyyy off.

illwood · Apr 16, 2005

Wow guys, that's some pretty poor dimensional analysis.

1 [ft^3] (cubic foot) = 28.317 [liters]

1 [ft^3/min] (cubic feet per minute) = 28.317 [liters/min] (just divided both sides by the unit 'minutes')

Therefore, 600 [ft^3/min] * 28.317 [liters/ft^3] = 16,990.2 [liters/min]

16,990.2 [liters/min] * 1/60 [min/sec] = 283.17 [liters/sec]

Make sense?

5spd GT · Apr 16, 2005

mackey said:
How does 1cfm equal 2 liters per second. Please link me to the source you got that from. That is wayyyy off.

It was off some link when I did a quick search for the definition...later on down it talked about air conditioning units though...so that could be the "difference"...

illwood - Nice copy and paste

illwood · Apr 16, 2005

5spd GT said:
illwood - Nice copy and paste

Copy and paste?

I have the piece of paper that I used right here to figure it out from the conversion of 1 inch = 2.54 centimeters and 1000 cubic centimeters = 1 liter.

Sheesh, give me some credit.

Definition of "CFM"

85_SS_302_Coupe

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