[s-cars] Crank Case Pressure and Turbo Smoke?

[Djdawson2 at aol.com]

In a message dated 2/22/2005 12:10:43 PM Mountain Standard Time, 
mark.pollan at mci.com writes:

> What will then happen to the bypass pressure?  It has to go somewhere so as 
> not to make hoses pop off or something else no?

The bypass pressure will go where it is intended to go... right back into the 
turbo compressor.  When bypass is active, air is just going around in a 
circle... in through the turbo inlet, out through the bypass to x-over tube hose 
(stock car), through the bypass valve, and back through the turbo inlet.  This 
keeps the compressor spinning faster for reduced lag... and keeps the 
compressor from experiencing sudden stall that can lead to the turbo shaft breaking.

  Does/should a blow-off valve then need to be plumbed in as well?
> 
> 


No.  The reason that our cars bypass air, rather than releasing it to 
atmosphere (blow off) is that our fuel systems use a MAF.  After air has passed the 
MAF, it has been "measured" and used to calculate the fuel requirement.  If you 
were then to release that air from the system, you would create a rich spike 
(too much fuel, not enough air).  This isn't a critical issue, but leads to 
poor drivability... every time you shift, the car will stumble badly, trying to 
burn all that excess fuel.
HTH,
Dave in CO