Re: schrick and RS2/S4

[bbell@csn.net (Bruce Bell)]

Hi Glen, 

The reason an rs2 will flow more air than an S4 turbo is due to the
temprature of the air at the compresser outlet. THe S4 turbo with the
smaller inlet will have to work harder to overcome backpressure as the rpm's
rise. While the boost may be the same, the temp will rise and the air
density will fall - hence less "air flow".  

>  I have a question about the statement "not moving more air, but
>  maintaining boost".
>
>  Is not the amount of air moved purely a function of the boost pressure,
>  all else being equal? In other words, if the S4 turbo can maintain the
>  same boost pressure as, for example, the RS2 turbo, at a given RPM, then
>  will not both turbos be moving the same amount of air? I should think
>  that so long as the smaller S4 turbo can "keep up" with the required flow
>  rate, ie the boost pressure does not drop below the WG setting, that the
>  S4 and the RS2 turbo would be moving the same amount of air and the
>  power/torque output would be equal. If this is all true, then the RS2
>  turbo would only have an advantage over the S4 turbo above the RPM level
>  that the S4 turbo could no longer maintain max boost due to flow
>  limitations, assuming of course that you could spin the engine fast
>  enough to have flow limitation with the S4 turbo.
>
>  Thoughts?
>
>  -glen

Bruce

bbell@csn.org (Bruce Bell)