ASP overdrive crank pulley for supercharger

I have a 9psi Powerdyne and a 7" ASP crank pulley myself, I am in the process of installing it as we speak so I can't really give my results but I have spoken to a few guys running the same combo.

I would suggest getting it tuned with the larger crank pulley so you can be done with it. The 7" ASP crank pulley should give you an additional 2psi or so.

You should be aware of the max impeller rpm for the Powerdyne BD series is about 40,000-42,000 rpms.

To calculate the actual rpm you will be spinning the blower use the formula below....

Crank Pulley Size/Blower Pulley Size x 3.05 x Your Shift RPM = Blower Impeller Speed

The 3.05 above is the Step Up value of the Powerdyne blowers.

So, for example my BD11A came with a 2.93" Blower Pulley (9psi pulley)
and the stock Crank pulley is 6.5"

6.5/2.93*3.05*5500rpm= 37214rpm This should be no problem at all.

I also have a 7" crank pulley which I plan to run after I get the car dialed in:

7/2.93*3.05*5500rpm= 40076rpm This will be just above the lower max limit for the BD11A and I should see 10-11 psi on the gauge at 5500 rpm with my stock heads.

Now, for example if I shift at 5400RPM instead of 5500 I should be able to have some insurance.

7/2.93*3.05*5400rpm= 39348rpm

Of course if you will be shifting higher then you will have to adjust accordingly.

HTH