RE: Turbo "energy"

[QSHIPQ@aol.com]

FYI, exaust gas is sonic exiting the valve.  A pressure wave is generated 
carrying energy at a high velocity.  Most of the energy is pressure, little 
is kinetic energy of gas movement (so EH is for runner size not friction).

If one looks at the "shorty" I5 manifolds, you have exhaust gasses exiting 
sonic from the valve, the manifold is very short, and has few bends.  
Pressure energy decreases and wave reflection increases with EM runner length 
and bends.    Attached not 10in from any valve, is the turbine, which will 
also increase the collection of heat, since the nozzle increases 
velocity=increase heat.  Since the nozzle (turbo hot side) is very close to a 
really thick and larger heat sink (manifold) you will get heat creeping from 
the turbo back towards the head.  Bottom Line of all this:  CC is used to 
increase velocity, on an already hot manifold tract, the gains will be 
minimal, and could be detrimental. 

If you increase the velocity (pre nozzle), you have in effect increased the 
A/R ratio, it's the same thing.  However, doing that may or may not help you. 
 Pulse turbo theory dictates that a reflection wave develops in the runners 
to a given collector.  The timing of the pulses in a given turbo application 
are matched to the A/R and the cut of the hot side wing itself.  So, it's not 
too hard to argue that without corresponding changes in the turbocharger 
application on an I5, CC may or may not positively affect turbocharger/engine 
performance.  My own thinking is I doubt it hurts, IME, it doesn't help.

For the calculations of heat increases in CC.  Read some of the sites on 
this, UP TO comes to you in a hurry.  Claiming a huge increase in the I5 
manifold makes "UP TO" very significant.  The path is already very efficient 
and contains high heat properties=high velocities.  Moving that heat to the 
turbo, can increase your chances of heat soaking the cold side across the 
bearing housing,  or heat soaking the head itself.  I argue, leave the 
manifold alone, it's a fine heat soak, right where you want it, let it get 
hot.  The combustion chamber is right where you don't want it (read alumimum 
head), and the stock turbo might not be anywhere close to where you want it 
(I'd bet if you cc'd a k24 manifold, you'd break the k24 turbo shaft).

Be smart, the theory doesn't support CC giving increased performance on the 
I5 turbo cars.  Baseline, one must understand *how* a turbo works in relation 
to a pulse converter (EM) and how turbo sizing works.  The former is pretty 
complicated, the later shows that the practical application is more important 
than theory.

HTH

Scott Justusson