Re: High Altitude Turbo Bar Question

[William_SWails@mail.amsinc.com]

     A few observations on Audi Turbos at higher elevations.
     
     I have measured the atmospheric pressure at various elevations, and 
     these are my measurements:
     
     Elevation (ft)  Atmospheric pressure (bar)
     --------------  ----
     0               1.00
     5500             .85
     8000             .77
     14400            .64
     
     There is obviously some variation due to weather conditions, but these 
     numbers are fairly stable.
     
     A reading with ignition switch on and engine NOT running of .8 in the 
     Colorado Front Range cities would be expected. My 89 200tq reads .8 in 
     Denver(5,000 ft) and .7 at home in Evergreen (8,000 ft) which is 
     reasonably in-line with my barometer readings above.
     
     I've had people tell me that the Audi Turbo is an "absolute" boost 
     system, and my observations support that. You should receive the same 
     maximum boost whether you are driving at sea level or 14,000 feet. 
     This means that no matter what the elevation you are driving, once the 
     turbo kicks in, you will have the same performance. On a non turbo 
     engine, performance would degrade at higher elevations. The only thing 
     lost driving a turbo at higher elevations is off-the-line acceleration 
     until the turbo begins creating boost.
     
     
     My max boost is around 1.4 which is comparable to what others have 
     reported. The turbo boost is dependent on engine RPM and load, so you 
     can't just rev up the engine at a stop light and see a boost increase. 
     but under load you should see around 1.4 bar boost.
     
     Hope this helps,
     
     -Bill-