Unfortunately, CFM is meaningless unless it is standardized. You need to know the mass of the air, since that determines the mass/weight of the fuel you can burn (air:fuel is a mass/weight ratio). Thats why it drives me nuts when turbos or compressor maps are rated in CFM. If you can find out in Lbs/min (which is becoming much more popular thee days) you can get an idea. As a general rule of thumb, every lb/min of air is good for 10 HP. Now, several factors affect this, mainly how efficiently you use that air. AFR, timing advance, etc. Its fairly accurate on well tuned cars.
Edit> If you know the temperature and pressure, you can convert CFM to lbs/min by the way. The formulas are out there on the internet I'm sure.