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Discussion Starter #1
Since a S/C, TT, etc is simply an air pump. I am wondering how the relationship of blower size and psi relate to both power and durability. Obviously a 2.3l Roots blower has to run a higher PSI to deliver the same volume of air as a 3.6L twin screw. Assuming the two blowers are delivering the same amount or air, does the increased pressure of the smaller blower put more strain on the motor? When people say that a stock block is pretty safe to xPSI would that "safe" number be lower with a bigger blower?

It would be interesting to hear some of the expert's thoughts on this. And I am thinking in general terms, not trying to get get into a "measuring" contest of A vs B, or brand "M" vs "K" or "P" vs "V", etc. Just trying to get a little education here.
 

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No, not all boost is equal.
10psi from a 3.0l blower is the same volume of air as 10psi from a 2.3l blower. The difference is that the larger blower will make that same amount of boost with less rpm meaning you can spin the blower slower. By spinning the blower slower, you free up more engine horsepower and you create less heat by doing so.

In short, a larger blower will make more power at the same boost level as a small blower as a result of cooler charge temps and less drag on the motor. That's also assuming the small and larger blowers are both from the same mfr.

Turbos and centrifugal blowers are an entriely seperate conversation.
 

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Also to add, blower efficiency comes into play as well.....which really throws a kink in the works....so a smaller super efficient blower and a larger inefficient blower can make the same power and the smaller might even make more at the same boost levels. Think new twin screw designs to old roots designs.
 

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Agreed which is why I stated that my scenario was dependant upon both blowers being from the same mfr which eliminates blower efficiencies and differences from one blower to another. My scenario is more for comparing a 2.8 vs a 3.6 from kb or for comparing a 2.3 to a 2.9 from Whipple.

Comparing a techco 3.0 to a maggie 2.3 is going to be very difficult.

In addition to blower size and design you have to considering intercooler efficiencies as well.
 

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Discussion Starter #5
Thanks, I thought this would be an interesting topic that causes a lot of confusion. I would think that most modern blowers are pretty efficient, that the extra effort to spin a bigger blower would wash with the extra effort to spin the smaller unit faster. I would also think that a bigger unit gives you more headroom for power later.
 
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Since Turbos use waste energy, they are very efficient compared to superchargers, which rob engine power to create boost. At any given psi level, ignoring tuning differences, a turbo will create more power at the wheels.
 
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