blower propeller rpm
crank pulley teeth / blower pulley teeth X blower gear ratio X MAX engine rpm
boost all depends on what motor you have, heads etc..

 

BDS has a chart for boost on its website

 

whats bds's website address?

 

Below is the chart from their website.


The boost levels listed in our charts are based upon an average that was determined by 39 years of experience testing superchargers. These boost readings were measured at wide open throttle and with the engine under load at 6000 RPM using a large bore blower unless otherwise specified.
There are two different 671 blowers commonly used. They are the larger diameter blower and the small diameter blower. The large bore blower (case thickness 1/2"-) is approximately 11 percent larger in volume than the small bore. The small bore blower (case thickness 3/4"+) is recommended for 370 CID engines or less for street applications. The larger bore blower is recommended for 371-500 CID engines in high performance, racing applications.

The actual boost readings from your system may vary greatly from the figures shown here. Aside from the possible differencein blower diameters, there are numerous things that will determine maximum boost levels.

1. Six most basic items that affect boost are listed below:
2. Cubic inches of the engine - more cubic inches means less boost.
3. Cam Shaft specifications - lift, duration, and lobe center play a big part in boost levels.
4. Size of the exhaust system - a small, restrictive exhaust can cause high boost readings.
5. CFM available to the blower - carbs that are too small will keep the blower from making maximum boost.
6. Blower size and drive ratio - larger blowers and higher drive ratios can create more boost.
7. Blower efficiency - blower efficiency is determined by the materials used and the methods of assembly.

BDS Stage 1 & 2 Blowers Only

471 Blower​

Cubic
Inches231262289350400-20%N/AN/AN/AN/AN/A-15%N/AN/AN/AN/AN/A-10%11.5 lbs9.5 lbs5 lbs3 lbs1 lbs-5%13 lbs11 lbs7 lbs4 lbs2 lbs1:114.5 lbs12.5 lbs8 lbs6 lbs4 lbs+5%15 lbs13 lbs9 lbs7 lbs5 lbs+10%16 lbs14 lbs10 lbs8 lbs6 lbs+15%17 lbs15 lbs11 lbs9 lbs7 lbs+20%18 lbs16 lbs13 lbs11 lbs9 lbs+25%N/AN/AN/AN/AN/A+30%N/AN/AN/AN/AN/A+35%N/AN/AN/AN/AN/A+40%N/AN/AN/AN/AN/A

671 Blower (Small Bore)​

Cubic
Inches289327350400427454500-20%3 lbs1 lbsN/AN/AN/AN/AN/A-15%5 lbs3 lbs1 lbsN/AN/AN/AN/A-10%7 lbs5 lbs3 lbs1 lbsN/AN/AN/A-5%9 lbs7 lbs5 lbs3 lbs2 lbsN/AN/A1:111 lbs8.5 lbs7 lbs4 lbs3 lbs2 lbsN/A+5%13 lbs10 lbs9 lbs6 lbs5 lbs4 lbs2 lbs+10%15 lbs12 lbs11 lbs8 lbs7 lbs5 lbs4 lbs+15%17 lbs14 lbs12 lbs10 lbs8.5 lbs7 lbs6 lbs+20%N/A15 lbs14 lbs12 lbs10 lbs8 lbs7 lbs+25%N/A17 lbs15 lbs14 lbs11 lbs9 lbs8 lbs+30%N/AN/A17 lbs16 lbs13 lbs10 lbs9 lbs+35%N/AN/AN/AN/AN/AN/AN/A+40%N/AN/AN/AN/AN/AN/AN/A

671 Blower (Large Bore)​

Cubic
Inches289327350400427454500550-20%9 lbs7 lbs5 lbs3 lbs2 lbs1 lbsN/AN/A-15%11 lbs9 lbs7 lbs5 lbs4 lbs2 lbsN/AN/A-10%15 lbs11 lbs9 lbs7 lbs6 lbs4 lbs1 lbsN/A-5%17 lbs13 lbs11 lbs8 lbs7 lbs6 lbs2 lbsN/A1:121 lbs15 lbs12 lbs10 lbs9 lbs8 lbs4 lbsN/A+5%23 lbs16 lbs14 lbs12 lbs11 lbs10 lbs6 lbs2 lbs+10%25 lbs18 lbs16 lbs14 lbs13 lbs12 lbs8 lbs4 lbs+15%27 lbs21 lbs18 lbs16 lbs15 lbs14 lbs10 lbs6 lbs+20%N/A24 lbs20 lbs19 lbs17 lbs16 lbs12 lbs8 lbs+25%N/AN/A22 lbs22 lbs19 lbs18 lbs14 lbs10 lbs+30%N/AN/AN/A24 lbs21 lbs20 lbs18 lbs14 lbs+35%N/AN/AN/AN/A24 lbs22 lbs20 lbs16 lbs+40%N/AN/AN/AN/AN/A24 lbs22 lbs18 lbs

871 Blower​

Cubic
Inches289327350400427454500550-20%11 lbs8 lbs6 lbs5 lbs4 lbs2 lbsN/AN/A-15%13 lbs10 lbs8 lbs7 lbs6 lbs4 lbs2 lbsN/A-10%15 lbs12 lbs10 lbs9 lbs8 lbs6 lbs4 lbs2 lbs-5%17 lbs14 lbs12 lbs11 lbs10 lbs8 lbs6 lbs4 lbs1:119 lbs16 lbs14 lbs13 lbs12 lbs10 lbs8 lbs6 lbs+5%21 lbs18 lbs16 lbs15 lbs14 lbs12 lbs10 lbs8 lbs+10%24 lbs20 lbs18 lbs17 lbs16 lbs14 lbs12 lbs10 lbs+15%26 lbs22 lbs20 lbs19 lbs18 lbs16 lbs14 lbs12 lbs+20%N/A25 lbs23 lbs21 lbs20 lbs18 lbs16 lbs14 lbs+25%N/AN/A26 lbs23 lbs22 lbs20 lbs18 lbs16 lbs+30%N/AN/A29 lbs25 lbs24 lbs22 lbs20 lbs18 lbs+35%N/AN/AN/A27 lbs26 lbs24 lbs22 lbs20 lbs+40%N/AN/AN/A29 lbs28 lbs26 lbs24 lbs22 lbsback to top

BDS Stage 2 Blower

871 Blower​

Cubic
Inches289327350400427454500550-20%13 lbs10 lbs8 lbs7 lbs6 lbs4 lbsN/AN/A-15%15 lbs12 lbs10 lbs9 lbs8 lbs6 lbs4 lbsN/A-10%17 lbs14 lbs12 lbs11 lbs10 lbs8 lbs6 lbs4 lbs-5%19 lbs16 lbs14 lbs13 lbs12 lbs10 lbs8 lbs6 lbs1:121 lbs18 lbs16 lbs15 lbs14 lbs12 lbs10 lbs8 lbs+5%23 lbs20 lbs18 lbs17 lbs16 lbs14 lbs12 lbs10 lbs+10%26 lbs22 lbs20 lbs19 lbs18 lbs16 lbs14 lbs12 lbs+15%28 lbs24 lbs22 lbs21 lbs20 lbs18 lbs16 lbs14 lbs+20%N/A27 lbs25 lbs23 lbs22 lbs20 lbs18 lbs16 lbs+25%N/AN/A28 lbs25 lbs24 lbs22 lbs20 lbs18 lbs+30%N/AN/A31 lbs27 lbs26 lbs24 lbs22 lbs20 lbs+35%N/AN/AN/A29 lbs28 lbs26 lbs24 lbs22 lbs+40%N/AN/AN/A31 lbs30 lbs28 lbs26 lbs24 lbsback to top

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Compressor Speed Forumula
(Crank pulley size / Blower pulley size x step up ratio) x max rpm


Crank Pulley 66
Blower Pulley 46
Step up Ratio 5
RPM 7800

Impeller RPM 55956.52174


Model Limitations Per ATI Max RPM Gearing
P1SC-1 65000 4.1
D1SC-1 62000 4.1
F1 70000 5.4
F1R 65000 5.4
F1C 75000 5.4