# Air Flow......................................>>>

2 replies to this topic
• # GRIMACE

Posted December 16, 2002 - 12:12 PM

Can anyone tell me what is the average airflow thru a 600 cc engine in CFM? guesses?
I got no idea.......

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
• # DesertChris

Posted December 16, 2002 - 09:15 PM

First I lets make an assumption of 100% volumetric efficiency. This just means that all 600cc are filled when the piston reaches BDC of the intake stroke. On a 4-stroke the intake stroke only happens every other stoke or at half the rpm (1000rpm = 500 intake stokes). Now for some conversions.

1cc = .00003531 cf (cubic feet)
* 600 = .021186 cf
cfm = (.021186)*(rpm/2)

10.59cfm @ 1000rpm
21.19cfm @ 2000rpm
31.79cfm @ 3000rpm
42.37cfm @ 4000rpm
52.97cfm @ 5000rpm
63.56cfm @ 6000rpm
74.15cfm @ 7000rpm
84.74cfm @ 8000rpm
95.34cfm @ 9000rpm
105.93cfm @ 10000rpm

A 10.59 increase change in cfm per 1000 rpm. On a naturally aspirated engine VE is dependent on many factors and the above scale would not be a constant increase. In actual use the above engine might only have 50% VE @ 10000rpm (300cc of combustable mixture). This is where cams, valve size, porting, intake and exhaust systems, etc. come into play.

• # GRIMACE

Posted December 17, 2002 - 07:27 AM

WOW . Thanks You shure do know alot about Engines , and I am very happy for your input . a VERY BIG THANK YOU !!!
LAMAR