Im thinking about trying a stupid project i won't mention right now but i need to know how many cubic feet per minute of air a stock 400ex pulls and i can't seem to find out. Any info would be appreciated

 

displacement times rpm

400cc's at 1000 rpm would be 400000cc's a minute or 400 liters

convert that too cubic feet now.

14.12 cubic feet per minute at 1000 rpm

105 gallons per minute @ 1000rpm

 

I think thats right. you may have to multiply buy 2 for the exhaust stroke.

 

Greatly appreciate it (never thought about calculating it myself) thanks!

 

theoretical cfm = rpm x displacement / 3456

But first the displacement of cc needs to be converted to cu inches.
1 cc = 0.0610237441 cubic inches so times 400 cc, gets 24.40948 cubic inches.
If you figure redline is about 7000, then 7000 times 24.40948 is 170,866.36 and that divided by 3456 equals 49.44 cfm,