I am in the process of trying to source another supercharger unit for the 20B FD. The one on it is a 1000 cfm unit but is far too small. We are at the maximum impeller speed with the pulley set up we have and it is only making 7 - 8 psi at 7400 rpm. The only problem is that it means at 3000 rpm its only got 2-3 psi of boost. I have emailed Procharger and they have asked what is the CFM/HP of the engine.
Does anyone know?
this is the link to the models they do, http://www.procharger.com/models.shtml
at the moment we have the equivalent of the first one on the list.
Hi Tony,
Well the capacity of the 20b is 120 cubic inches.13b is 80 cubic inches.
So by multiplying that by say 7000 rpm and adding 20%,then dividing by 1728 cubic inches(1 cubic foot) you get 583 cfm.Say 600 cfm to be sure.we all ways go over the actual capacity of the rotary because it can with the right porting and ancillaries be quite well over 100% volumetric effiency.
So that makes sense with your charger being to small at only 1000 cfm.
Forgot to mention that on a 13b PP engine we run a holley carb of 650cfm.On a stock 13b it would be around 450cfm.
Regards
Carl