amen to voldo
There is no reason to bypass the supercharger apart from when you close the throttle. The supercharger compresses the air at a pressure ratio. It doesn't care if the air coming in is 14.7psi or 25psi
To save you from trolling through buzzed's thread start here:
http://www.alfabb.com/bb/forums/engine- ... ct-14.html
Quote from Greg Gordon
"It might be best to explain this with some simple math (not technically complete or perfect by any means). A Roots blower creates a pressure ratio which is defined as outlet pressure/inlet pressure. We tend to express supercharger outlet as boost and a lot of people like to talk about flow, but in this case it's easier to understand it via pressure ratios. Roots blowers create pressure ratios, and that's critical to understand when building a compound system.
Here is an example: atmospheric pressure at the supercharger's inlet is 14.7psi (sea level standard day), in this case our supercharger is set up to provide 7.35 pound of boost so the outlet pressure is 22.05psi. Outlet pressure divided by inlet pressure is 22.05/14.7=1.5. So our pressure ratio is 1.5:1
Now lets keep everything the same with this supercharger except we will add pressure to the inlet side with either another supercharger, or a turbocharger. The pressure ratio will stay the same but boost from the supercharger will increase. To keep it simple, lets add 5psi to the inlet.
Now we have 19.7 at the inlet and the supercharger will give us a pressure ratio of 1.5:1. When we multiply the inlet pressure by the pressure ratio we get 29.55psi. Subtract 14.7psi and we find we have 14.85 pound of boost. What happening here? The supercharger by itself only gave 7.35psi and we only added 5psi. Add those two numbers together and they total 12.35psi but we have 14.85 pounds of boost! This is one of the beautiful things about a compound system.
Greg "
