cfm calc

[Greg Hermann]

>I had read inthe archives that they were sized
>based on a 1.5"Hg drop for two barrels and a 3"Hg
>drop for 4barrell(across the throttle).

Other way around. 2 barrels are rated on the higher pressure drop.

You can calculate it OK based on diameter of the throat, but entry shape
has _SO_ much to do with it, that you are not gonna get an exact number
anyway without testing. Like Bruce sez--all the numbers will get you is
close!

Greg

I also had
>seen calcs for engine cfm requirements at 100%VE.I
>am assuming I can get %VE from cam
>manufacturers(maybe a curve).The throttle body on
>the manifold I have  has been guesstimated at
>about 500cfm-from the rough calc inthe archives
>the engine reqrments about 546cfm.I am also
>wondering what pressure drop would be caused by a
>turbo at moderate boost
>conditions(dreaming)(something like accel
>turbosonic adapter-draw thru).
>Mike Swayze
>
>Bruce Plecan wrote:
>>
>> ----- Original Message -----
>> Subject: cfm calc
>>
>> The Holley TBI with 1.68 butterflies is called a 400 CFM, and the 2"
>> butterfly version a 670 CFM.  If your running something other than TBI it