[s-cars] Stock boost levels?

[Robert Myers]

At 10:19 AM 6/9/2004 -0600, mlp5 wrote:

>My conversion chart/table tells me 1 bar = @14.50377 psi.
>In less than round numbers, 2.2 works out to something like 31.9086 psi, 
>so say 32 psi.

That is ~32 psia - psi absolute.  Boost is usually measured in psig - psi 
gauge.  The difference is the 14.7 psi of standard atmospheric 
pressure.  32 psia = ~ (32 - 14.7) = ~17 psig

>
>I don't know what one is supposed to use for "normal" atmospheric pressure 
>or how that should be applied to determine a psig number.  I guess the 
>"normalized" number for average days at sea level is 14.7.  In Everboost 
>my guess is that would be something more like 12, and for the lesser 
>beings living below Everboost (down another 2,000' of elevation or so), 
>say12.5 to 12.7 psi.  I've been assuming that the 14.5, 14.7 and by 
>extrapolation 12, 12.5 and 12.7psi all represent values measured from 
>"total vacuum, or "0".  So your 20 psig would work out to anything from 
>34.7 psia at "sea level" to, say 32.0 psia in Everboost?
>
>I guess the devil must be in the details.  In the mean time I'm still 
>sticking with my last paragraph, the ".... 18psi dropping to 15-16...."

That's pretty close, certainly good enough for state work.  ;-)

>
>If I have a question about the numbers Bob, it would be should one 
>subtract 1 bar, i.e. a fixed, never variable 14.50377psi, from Lino's 
>(presumptively misplaced decimal) 2.2 bar Gauge reading, or 1 "local" 
>atmosphere, say 14.7 psi for those low life, low lander Canadians (maybe 
>plus a 1/10th or two for their generally coLD weather) to determine how 
>much boost he thinks he's running.

Aw, Canucks aren't all that bad, some of them anyway.  :-)))  That's about 
the only realistic way you have for doing the calculations, Mike.  2.2 bar 
= ~32 psia = ~(32 - 15) psig = ~ 17 psig of boost.   If you need to know 
the pressure differential between manifold pressure and local atmospheric 
pressure you would subtract the local pressure (in psi units) from the The 
nicety of using bar measurements is that you don't have to try to keep 
track of atmospheric pressures in the calculations.  (32 - 12 {or so}) = 20 
{or so}.

>
>mike
>-----Original Message-----
>From: Robert Myers [mailto:robert at s-cars.org]
>
>You are forgetting one little detail.  Bar are usually measured in 
>absolute terms.  2.2 bar would be 2.2 bar above total vacuum.  In round 
>numbers 2.2 bar is about 35 psia or about 20 psig (or 20 psi above 
>"normal" atmospheric pressure).  That is about 20 psi of boost.  This is 
>well within reach of a mildly chipped S-car and not that far above an 
>unchipped s-car which would normally peak out at about 16 or perhaps 17 
>psig of boost.
>
>
>At 09:15 AM 6/9/2004 -0600, mlp5 wrote:
>
>>Missing a decimal point would still put Lino's gauge in the @ 31 psi peak
>>[MLP]
>>
>>..... snips   ....
>>
>>Until Lino clears it up, I think I'll go with the missing a decimal point &
>>somehow reading/reporting absolute pressure for @ 18psi,
>>dropping/stabilizing at @ 14 to 16psi (i.e., 2.1-1= 1.1x14.5=15.95)
>>interpretation.  Which after all, FWIW would seems more normal for a stock,
>>unchipped ECU.  But, OTOH if Lino is regularly running 30+psi I'd be pretty
>>interested in how he's doing that too :-)
>>
>>mike

_____

Middle of the road?  There is nothing in the middle of the road except 
yellow stripes and dead possums.


Bob
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  Robert L. Myers  304-574-2372
  Rt. 4, Box 57, Fayetteville, WV 25840 USA  WV tag Q SHIP
  '95 urS6 Cashmere Grey - der Wunderwagen   ICQ 22170244
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