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Old 10-03-2013, 03:25 PM   #12
Mr Wrex
Scooby Specialist
Member#: 332887
Join Date: Sep 2012
Chapter/Region: Tri-State
Location: Orange County, NY
2012 WRX stage 2+
DGM (sedan)


Originally Posted by CarverHouseRally View Post
This is not true.

The goal is to minimize the pressure drop between the inlet of the intake system and the turbo. To find the total pressure drop you sum the pressure drops across each component. A 3" hose will have a slightly smaller pressure drop for a given mass flow rate compared to a 2.4" hose, as the velocity will have to be higher to maintain the same mass flow rate. Velocity=frictional losses within the fluid. So even if you flow through a 2.4" orifice (the compressor housing inlet) in both cases, you will still have a higher total pressure drop using a 2.4" hose. In reality the difference will probably not be noticeable though.
Pulling air through a 3" diameter pipe into a 2.4" diameter pipe will flow at the same exact rate as using a pipe that is 2.4" all the way through if you don't take pressure drop into account. I didn't even bother mentioning that since, in reality, that pressure drop is barely noticeable.
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