Re: Turbos, HP and Real World...

[glen.powell@smc.com]

  We're getting closer here.... Yes, turbos can be setup and measured to
  observe certain flow rates are certain RPM. If a turbo for a given
  application is sized correctly the trubo will be capable of providing
  sufficient flow at "normal" turbo operating RPM and maximum engine RPM
  while maintaining max boost as controlled by the WG/computer. Any flow
  capability of the turbo above and beyond that required to fill the
  cylinders at max engine RPM and while maintaining max boost pressure is
  wated, the turbo is "too big" for the application. Only if the turbo
  cannot maintain maximum boost pressure at maximum engine RPM is turbo
  flow rate really an issue, turbo "too small" for the application. If a
  given setup has just enough turbo flow at max engine RPM to maintain max
  boost and modifications are then made to the engine that increase the
  flow capabilities of the engine, cam, open exhaust, head porting, etc,
  then a "small" turbo might start to limit the flow capabilities of the
  overall system. Tubo flow limitations would be directly observable as a
  drop in boost pressure from the maximum as engine RPM increases and
  engine intake demand outstrips the flow capability of the turbo. All this
  is a long-winded way of saying if the boost pressure does not drop below
  the maximum boost allowed by the WG then the turbo is not "too small" and
  the flow capability of the trubo is sufficient for the application and
  that a larger and/or higher flow rate turbo would not increase
  performance in the same application. If a replacement turbo could
  maintain the same max boost pressure at max engine RPM (flow rate) but do
  so at lower outlet temperatures (higher efficiency) then there definitely
  would be an advangate to the replacement turbo.

  -glen