[s-cars] Turbo Compressor Maps

[Cody Payne]

Ok...so you dont count the HP that the car would have if it was Normally Aspirated?  As I was taking my incorrect NA number of 130 and adding to the 25 lb/min = 380.  But if you say I dont count that initial number and say I want 380HP then I need to flow 38 lb/min...

If that is the case the Compressor maps make more sense now...in terms of efficiency ranges and plots for the 50 and 54 trim.

One thing I still am fuzzy on, among others, what does it mean to have a Stage V turbine?  What is the difference?  Also any one think it is worth doing Ceramic Ball Bearings?

cp

-----Original Message-----
From: Michael Gough [mailto:mdg3369 at newtsplace.com]
Sent: Wednesday, August 06, 2003 3:46 PM
To: Cody Payne; s-car-list at audifans.com
Subject: Re: [s-cars] Turbo Compressor Maps


> Now if the 2.2L engine normally aspirated could say put out 130 HP then to
> get up to around 380 HP I would need around 25 lb/min right?

No...
A very rough estimate is 10hp = 1 lb/min. This leads to 38lb/min for 380hp,
and at a pressure ratio of 2.63:1, both the 54 and 57 trim compressors are
about 70% efficient, based on my quick look at the maps right now. Now of
course this assumes that you are actually flowing 38lb/min of air through
the motor at 2.63:1 pressure ratio, if you're flowing more or less, you have
to re-plot these points on the maps.
And of course if you're flowing 38lb/min of air at 6000 RPM, you'll flow
roughly (Not exactly because of changes in VE) half that much air at 3000
RPM, which would put you very far to the left of the surge line. Make sure
you size the exhaust housing large enough so that you don't make 25psi of
boost at 3000 RPM, or program your boost control so that it doesn't allow
you to make too much pressure at too low of an airflow so that you stay out
of the surge area.
HTH
Mike