Pulley size on my supercharger

[dj65falcon]

Went to vortech website to use the calculator for impeller speed. right now the supercharger has a 3.62 pulley on it. Right now it is producing 6.5 lb of boost. On the vortech calculator it is spinning at 35,801.10. I want to put my 3.33 pulley on. It calculates the speed to be 38918.92. so how much extra pounds of boost will this give me? I am assuming maybe 1 lb. But I will need your guys help on this. Thank you on a happier note. I ran at the track yesterday 11.98 at 109. Here is my time slip

 

[pmuller9]

Absolute pressure = 6.5 + 14.7 = 21.2

21.2/35801 x 38919 = 23 absolute.
23 - 14.7 = 8.3 psi

OR
6.5 + 14.7 = 21.2
21.2/3.33 x 3.62 = 23
23 - 14.7 = 8.3

 

[dj65falcon]

Sweet. So that should give a extra 20 hp, I think. Still little more boost is good

 

[pmuller9]

Sweet. So that should give a extra 20 hp, I think. Still little more boost is good

If you are making 350 hp at 6.5 psi, 8.3 psi is a 9% change in absolute pressure or about a 30 hp increase in power.

 

[pmuller9]

Are you just doing a "test & tune" at the track, or will you run some elimination rounds?

 

[dj65falcon]

Are you just doing a "test & tune" at the track, or will you run some elimination rounds?

Just test and tune. I am done for this year. That was my last run, that I ran a 11.98. but my a/f was at 13 5. Very lean. My front jets were 75 and my rear was 84. All the spark plugs were white. Lucky I was running 100 octane racing gas. Plus I was only shifting at 5800. Not my normal 6200. So I am going to have to figure out how many more jet sizes up to get the fuel ratio in the 11.5-12

 

[pmuller9]

I don’t remember.
Did you drill out the power valve passages in the carburetor?